# Generator for Food Truck



## HARRY304E (Sep 15, 2010)

Dennis Alwon said:


> Ok I will premise this with 2 things. Firstly I know that food trucks do not fall under the NEC and secondly, I know little about gensets.
> 
> We were asked to wire a food truck for a customer. We got the truck wired and then he shows us the genny. I have never seen one with this setup. It is a cummins genny made specifically for food trucks. The nameplate is 58 amps 120V. The leads coming from the genny are connected to a 2p 30 amp breaker which I assume are in phase. The leads are 2- #12 white, 1- #12 Black, 1- #12 Black with yellow tracer and a #12 green
> 
> Here is the schematic--- My question is whether or not this is a setup for parallel wiring. In other words do I parallel the neutrals and hots or what?



It looks like it to me,also I would wire it just like a commercial kitchen,210.8(B)...


----------



## Big John (May 23, 2010)

Looks to me like they've taken a dual-voltage single-phase generator and reconfigured it for 120V loads. I.e.: If they wanted to, they could also wire that for 240V applications without using a different stator.

So in your setup those windings would be in phase, and the current would be additive: That's why they doubled up the neutral conductors. 

I can't think of anything off hand that would prevent them from being paralleled as long as you observed the same conductor sizes, and I would parallel the neutrals onto a common bus. But for simplicity because the hots are already on separate generator breakers, I would land each on it's own bus leg in a small single-phase panel. In the event that one leg does down, this also allows you to continue running, whereas a parallel installation would fail completely.


----------



## Dennis Alwon (May 9, 2009)

Big John said:


> Looks to me like they've taken a dual-voltage single-phase generator and reconfigured it for 120V loads. I.e.: If they wanted to, they could also wire that for 240V applications without using a different stator.
> 
> So in your setup those windings would be in phase, and the current would be additive: That's why they doubled up the neutral conductors.
> 
> I can't think of anything off hand that would prevent them from being paralleled as long as you observed the same conductor sizes, and I would parallel the neutrals onto a common bus. But for simplicity because the hots are already on separate generator breakers, I would land each on it's own bus leg in a small single-phase panel. In the event that one leg does down, this also allows you to continue running, whereas a parallel installation would fail completely.



That is exactly what I was thinking except that I was going to parallel the hots also. If one overloads so will the other as they are connected to a common dp breaker


----------



## Dennis Alwon (May 9, 2009)

I am definitely not going to mes with the inside of the genny as the tails are already out. Surprising to me is that they parallel #12 to get 58 amps when #12 is 20 amps --- supposedly

On second thought I think you John is correct about splitting the hots to each phase.


----------



## Dennis Alwon (May 9, 2009)

It also states


> 1. These are not reconnectable generators
> 2. Because generator windings T1-T2 and T3-T4 are in phase the neutral conductor in the connected equipment such as between the transfer switch and main distribution panel must be sized to carry the sum of the load.


I guess they decided to parallel 2- #12 to get a possible 58 amps????? but want the field to run full size-- well in this case there is no transfer switch just generator power.


----------



## Big John (May 23, 2010)

Ah, there's your answer. It even says they're in phase. 

If I had to guess, the double-pole breaker is probably standard for that generator package. That way all they do if they want to switch to 120/240V applications is pop in a 15A and make the neutral T2+T3.


----------



## Dennis Alwon (May 9, 2009)

Thanks John. My guys are finishing it up so it was good to get the feed back. We don't usually work weekends so I gave them this job to do and get paid from the owner. They will appreciate the extra bucks.


----------



## Meadow (Jan 14, 2011)

The neutrals would be paralleld, use a number 6. Keep the phases separate as a #12.


As big john said, the phase angle is the same. Best way to think of this is 2 12 volt car batteries. Normally they would be connected in series - + -+, the outer most terminals would give 24 volts while the inner 2 terminals jumped would be the neutral point. The neutral would never see double the ampacity because the neutral current is subtractive. However in this case we are dealing with a - + + - setup. Im essence we are no longer dealing with series windings but paralleled. The neutral is now additive an only 12 volts would be available between neutral and hot while 0 between the 2 hots. In this case its just windings in AC with 120 volts. 


Top most is the gen bottom left is typical 120/240:


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> The neutrals would be paralleld, use a number 6. Keep the phases separate as a #12.


Can't do. They have factory #12's paired coming from the genset. This unit has the leads already coming out of the genny

The battery analogy is a good one. I read that analogy many years ago from a member at mike holt forum. Thanks


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> Can't do. They have factory #12's paired coming from the genset. This unit has the leads already coming out of the genny
> 
> The battery analogy is a good one. I read that analogy many years ago from a member at mike holt forum. Thanks


Ok. Do the specs say anything about grounding the neutrals?


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> Ok. Do the specs say anything about grounding the neutrals?


No as they have a separate green conductor.


----------



## Dennis Alwon (May 9, 2009)

The interesting thing is the manual says that the unit is equipped with #10 125C irated insulation for the power. NOT-- its is #12


----------



## Meadow (Jan 14, 2011)

I guess they run floating then. I only ask because normally on home gens the neutral is jumped to the egc in the housing like in a service to give the neutral a ground reference. 


But I guess since its only 1 or 2 machines connected to the gen the system ungrounded might actually be safer. 


Any GFIs on the plugs?


----------



## Dennis Alwon (May 9, 2009)

We install a small 12 circuit panel and installed all gfci protected outlets inside and outside the truck.


----------



## Big John (May 23, 2010)

meadow said:


> I guess they run floating then. I only ask because normally on home gens the neutral is jumped to the egc in the housing like in a service to give the neutral a ground reference....


 Seems like it could still well be. I'd check to be sure there was already a bond between the neutral and supplied EGC and if so, wire accordingly.


----------



## Dennis Alwon (May 9, 2009)

The neutrals and equipment grounding conductor do not ohm out so they are not connected together


----------



## EJPHI (May 7, 2008)

It would help a lot if they put dots on the transformer windings shown in the schematic. With dots you always know how to correctly connects windings.

You probably want to skip the ground rod on this installation.

EJPHI


----------



## Dennis Alwon (May 9, 2009)

EJPHI said:


> You probably want to skip the ground rod on this installation.
> 
> EJPHI


Yeah that would be a good idea. My guy joking got me asking me if they should install a rod. I looked at him and he laughed...


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> The neutrals and equipment grounding conductor do not ohm out so they are not connected together


If the manual doesn't say anything about grounding down the neutral just leave it as is.


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> If the manual doesn't say anything about grounding down the neutral just leave it as is.


That's what I told them to do. In the panel the neutral is isolated from the equipment grounding conductor.


----------



## Big John (May 23, 2010)

Are you still making sure you have good EGCs but just leaving out the system bonding jumper?


----------



## Dennis Alwon (May 9, 2009)

Big John said:


> Are you still making sure you have good EGCs but just leaving out the system bonding jumper?


Well I just assumed they have the green conductor attached to the frame. Not sure where else it would be attached to since it did not have continuity to the neutrals.


----------



## RandyM (Apr 5, 2012)

I would not run with a floating neutral. Bond it a the generator if the manufacturer did not do it.


----------



## Big John (May 23, 2010)

Dennis Alwon said:


> Well I just assumed they have the green conductor attached to the frame. Not sure where else it would be attached to since it did not have continuity to the neutrals.


 Agreed, but I mean with the circuits you're running within the truck, will they have an EGC back to a bus, or are you omitting that?

My point is that I think in the event that this truck gets beat up and the wiring gets damaged, I think you still want an effective fault clearing path even if you're running the generator floating.


----------



## Dennis Alwon (May 9, 2009)

Big John said:


> Agreed, but I mean with the circuits you're running within the truck, will they have an EGC back to a bus, or are you omitting that?
> 
> My point is that I think in the event that this truck gets beat up and the wiring gets damaged, I think you still want an effective fault clearing path even if you're running the generator floating.


We ran emt with an equipment grounding conductor inside the truck.


----------



## markore (Dec 7, 2011)

Dennis Alwon said:


> Ok I will premise this with 2 things. Firstly I know that food trucks do not fall under the NEC and secondly, I know little about gensets.


Firstly, thanks for posting this very interesting topic.
Secondly, you can write a nice disclaimer. :thumbup:


----------



## Meadow (Jan 14, 2011)

RandyM said:


> I would not run with a floating neutral. Bond it a the generator if the manufacturer did not do it.


Considering this is a stand alone it might be safer. But regardless the EGC and all metal should be bonded together and including the generator stator.


----------



## Dennis Alwon (May 9, 2009)

RandyM said:


> I would not run with a floating neutral. Bond it a the generator if the manufacturer did not do it.


This think is made for vehicles-- I am not going to mess with the genny-- I will call the company tho.


----------



## Dennis Alwon (May 9, 2009)

I was thinking if I bond the neutral and and equipment grounding conductor at the panel that would basically do the same as bonding in the genny-- well not really. The problem is when installed I doubt we can get to it. The way it is now if there is a hot to ground short the breakers would not trip. I am definitely calliing the company-- geez and they do this for a living.


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> I was thinking if I bond the neutral and and equipment grounding conductor at the panel that would basically do the same as bonding in the genny. The way it is now if there is a hot to ground short the breakers would not trip. I am definitely calliing the company-- geez and they do this for a living.


A hot to ground short wouldn't do anything as long as everything is bonded together with an egc running to a ground bar and the ground bar is also bonded to the frame. Down side would be the fault would go unnoticed and a second one an opposite phase might trip 2 breakers. 


Double check first though, manufacturing might ask for one or the other.


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> A hot to ground short wouldn't do anything as long as everything is bonded together with an egc running to a ground bar and the ground bar is also bonded to the frame. Down side would be the fault would go unnoticed and a second one an opposite phase might trip 2 breakers.
> 
> 
> Double check first though, manufacturing might ask for one or the other.



What about when you step from grade to the food truck? There will be a difference in potential and someone could get hurt


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> What about when you step from grade to the food truck? There will be a difference in potential and someone could get hurt


Not if everything is bonded correctly. A ground on any part of the system will be no different then grounding the neutral at the source. Milli amps of current will flow. The second fault will behave like that on a regularly grounded system.


----------



## markore (Dec 7, 2011)

Big John said:


> Ah, there's your answer. It even says they're in phase.
> 
> If I had to guess, the double-pole breaker is probably standard for that generator package. That way all they do if they want to switch to 120/240V applications is pop in a 15A and make the neutral T2+T3.


To get 240V from this existing stator you are saying you would need to break T3 off CB2, splice T3 with T2 and connect T4 to CB2 to make that happen...? And then the optional neutral would be an optional tap at the T2/T3 splice?


----------



## Barjack (Mar 28, 2010)

It looks like you have to bond the white wires (they don't really fit the bill of a neutral, as there is no imbalance) to the generator frame.

From the 2008 NEC:



> *250.34 Portable and Vehicle-Mounted Generators.*
> (A) Portable Generators. The frame of a portable generator
> shall not be required to be connected to a grounding
> electrode as defined in 250.52 for a system supplied by the
> ...





> *250.26 Conductor to Be Grounded—Alternating-Current
> Systems.*
> For ac premises wiring systems, the conductor to
> be grounded shall be as specified in the following:
> ...


----------



## markore (Dec 7, 2011)

If everything is cord and plug connected, it is not a SDS.


----------



## drsparky (Nov 13, 2008)

What about the FOOD, what kind and any good?


----------



## Wirenuting (Sep 12, 2010)

drsparky said:


> What about the FOOD, what kind and any good?


I hope there is coffee & raspberry jelly donuts with powered sugar..


----------



## Barjack (Mar 28, 2010)

markore said:


> If everything is cord and plug connected, it is not a SDS.


I'm not sure what you mean by that.


----------



## Dennis Alwon (May 9, 2009)

markore said:


> If everything is cord and plug connected, it is not a SDS.


It is a direct wired generator feeding a panel.


----------



## chicken steve (Mar 22, 2011)

I'm reading _'system bond'_ as a fairly new term, not sure how it might be applicable here.....

~CS~


----------



## markore (Dec 7, 2011)

(B) Vehicle-Mounted Generators. The frame of a vehicle
shall not be required to be connected to a grounding
electrode as defined in 250.52 for a system supplied by a
generator located on this vehicle under the following
conditions:
(1) The frame of the generator is bonded to the vehicle
frame, and
*(2) The generator supplies only equipment located on the
vehicle or cord-and-plug-connected equipment through
receptacles mounted on the vehicle, or both equipment
located on the vehicle and cord-and-plug-connected
equipment through receptacles mounted on the vehicle
or on the generator, and*
(3) The normally non–current-carrying metal parts of
equipment and the equipment grounding conductor terminals
of the receptacles are connected to the generator
frame.

Then as long as only equipment located on the vehicle is supplied, and that equipment frame and vehicle frame are bonded to generator frame, the neutral does not have to be bonded unless the generator is a component of a separately derived system.

It is not a SDS unless the grounded conductor is transfer switched.

250.20 (D) Separately Derived Systems. Separately derived systems,
as covered in 250.20(A) or (B), shall be grounded as
specified in 250.30(A). Where an alternate source such as
an on-site generator is provided with transfer equipment
that includes a grounded conductor that is not solidly interconnected
to the service-supplied grounded conductor, the
alternate source (derived system) shall be grounded in accordance
with 250.30(A).
FPN No. 1: An alternate ac power source such as an onsite
generator is not a separately derived system if the
grounded conductor is solidly interconnected to a servicesupplied
system grounded conductor. An example of such
situations is where alternate source transfer equipment does
not include a switching action in the grounded conductor
and allows it to remain solidly connected to the servicesupplied
grounded conductor when the alternate source is
operational and supplying the load served.
FPN No. 2: For systems that are not separately derived and
are not required to be grounded as specified in 250.30, see
445.13 for minimum size of conductors that must carry
fault current.


----------



## markore (Dec 7, 2011)

chicken steve said:


> I'm reading _'system bond'_ as a fairly new term, not sure how it might be applicable here.....


System conductor or system bond implies service entry which a vehicle mounted generator does not utilize?

Guys disclaimer I'm new to gensets also, just trying to help bump this thread up and keep the discussion going...


----------



## chicken steve (Mar 22, 2011)

markore said:


> System conductor or system bond implies service entry which a vehicle mounted generator does not utilize?
> 
> Guys disclaimer I'm new to gensets also, just trying to help bump this thread up and keep the discussion going...


well i read it in 250.30 Mark

~CS~


----------



## Barjack (Mar 28, 2010)

Markore, what you quoted only talks about electrodes, which I agree are not required here. It does seem though that at least one conductor must be bonded to the generator frame.


----------



## Barjack (Mar 28, 2010)

IMO, a vehicle generator meets the definition of an SDS.



> Separately Derived System. A premises wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct connection from circuit conductors of one system to circuit conductors of another system, other than connections through the earth, metal enclosures, metallic raceways, or equipment grounding conductors.


----------



## Meadow (Jan 14, 2011)

Does the NEC even apply to a food truck?


----------



## markore (Dec 7, 2011)

Barjack said:


> IMO, a vehicle generator meets the definition of an SDS.


Is a vehicle a premises?



> Separately Derived System. A *premises* wiring system whose power is derived from a source of electric energy or equipment other than a service. Such systems have no direct connection from circuit conductors of one system to circuit conductors of another system, other than connections through the earth, metal enclosures, metallic raceways, or equipment grounding conductors.


----------



## Barjack (Mar 28, 2010)

markore said:


> Is a vehicle a premises?


It can be on a premises, just like a portable generator can.


----------



## markore (Dec 7, 2011)

meadow said:


> Does the NEC even apply to a food truck?


No as originally stated by Dennis in the OP because a vehicle is not a premises.



wikipedia said:


> Premises are land and buildings together considered as a property. This usage arose from property owners finding the word in their title deeds, where it originally correctly meant "the aforementioned; what this document is about", from Latin prae-missus = "placed before".
> 
> In this sense, the word is always used in the plural, but singular in construction. Note that a single house or a single other piece of property is "premises", not a "premise", although the word "premises" is plural in form; e.g. "The equipment is on the customer's premises", never "The equipment is on the customer's premise".


If it was premisis wiring ground rods and bonding would be required. The wiring diagram Dennis showed keeps them separate.


----------



## Barjack (Mar 28, 2010)

The NEC doesn't apply to wiring necessary for the vehicle to operate, but it does apply to generators mounted on a vehicle.


----------



## markore (Dec 7, 2011)

Barjack said:


> It can be on a premises, just like a portable generator can.


A portable generator becomes a SDS when connected to premises wiring using a transfer switch which disconnects the neutral.


----------



## nrp3 (Jan 24, 2009)

What I find interesting is most portables are bonded. Why would this situation be any different? You would think this would need it too.


----------



## markore (Dec 7, 2011)

Barjack said:


> The NEC doesn't apply to wiring necessary for the vehicle to operate, but it does apply to generators mounted on a vehicle.


The grounding sections yes. The bonding section only applies to SDS meaning connected to premises wiring by switched ungrounded and grounded conductors (transfer switch).


----------



## Barjack (Mar 28, 2010)

Just so I'm clear, how would a line to case fault operate the OCPD if one of the conductors is not bonded to the frame?


----------



## markore (Dec 7, 2011)

nrp3 said:


> What I find interesting is most portables are bonded. Why would this situation be any different? You would think this would need it too.


Because in this case the earth itself is not bonded there is no difference of potential or way to complete the circuit through the chassis therefore safety and increased by not bonding the neutral. It also limits parallel current paths and EMF.


----------



## markore (Dec 7, 2011)

Barjack said:


> Just so I'm clear, how would a line to case fault operate the OCPD if one of the conductors is not bonded to the frame?


No current would flow unless there was also a fault from the neutral to the frame.
*I don't proclaim to be an expert on gensets I'm just playing along with the way I read these sections and the fundumentals. I am a tradesman by day and electrical engineering student by night. *

You are not forbidden to bond the grounded conductor. (neutral) The only position I am advancing is that you are not required to... and there may be some cases where it may be desirable not to.

As Dennis described all his outlets were GFI's which operate without ground rods or bonding and provide 5ma protection which is much more protective than breakers.

I would feel very comfortable feeding fixed equipment in the vehicle with a GFI breaker and no neutral bonding provided all equipment chassis were connected to the grounding conductor as specified in the NEC sections I quoted.

In harbors similar conditions exist because boats have gensets and they have started requiring the premise wiring have 30ma GFIs on all main breakers since GFI protection is much more protective than regular breakers around water.


----------



## nrp3 (Jan 24, 2009)

The frame of a portable is bonded so that a line to frame fault would cause the breaker to open or some other bonded metal through an extension cord to a tool for instance. Without this, I would think the whole metal frame or metal portions of appliances could be live. Someone standing on the ground touching the vehicle could catch a shock in this case I would think.


----------



## markore (Dec 7, 2011)

nrp3 said:


> The frame of a portable is bonded so that a line to frame fault would cause the breaker to open or some other bonded metal through an extension cord to a tool for instance. Without this, I would think the whole metal frame or metal portions of appliances could be live. Someone standing on the ground touching the vehicle could catch a shock in this case I would think.


That is a misconception. AC and DC are not attracted to the ground the same way static electricity discharges. They only complete full circuit paths.

This is not static electricity meaning even if the frame was directly connected to 120V side of genset, there will not be a difference of potential to the ground because the ground is not connected to the neutral side of the genset. 

The ground only becomes dangerous when it is bonded to the neutral side.
In vehicles you should be as careful with the neutral as you normally would be with the "hot". It takes connection to both sides of the coil to create a difference of potential.

If you bond the entire frame, as you noted, it would be much easier to have the user get shocked and complete the circuit by touching the "hot" because of the probability of the user also touching the chassis.

If the chassis is not bonded the user should not be shocked by touching only the "hot" because there is no completed circuit. You can test this yourself with doorbell transformers.

Again, I am not an expert, just a student looking at the fundementals. YMMV._
Beware of faulty equipment with leakage between the grounding or grounded conductors._
And remember with AC the neutral (grounded conductor) can be just as dangerous as the ungrounded conductors because it is often not switched with breakers.


----------



## Barjack (Mar 28, 2010)

markore said:


> That is a misconception. This is not static electricity meaning even if the frame was directly connected to 120V side of genset, there will not be a difference of potential to the ground because the ground is not connected to the neutral side of the genset. The ground only becomes dangerous when it is bonded to the neutral side. In vehicles you should be as careful with the neutral as you normally would be with the "hot". It takes connection to both sides of the coil to create a difference of potential. If you bond the entire frame, as you noted, it would be much easier to have the user complete the circuit because of the probability of the user toughing the chassis.


 You really are confusing grounding and bonding.

And if you don't bond the neutral, you run the risk of a line to case fault going unnoticed.


----------



## nrp3 (Jan 24, 2009)

True, without a connection to earth there's no reference there or path back to neutral.


----------



## markore (Dec 7, 2011)

This should help:
Mike Holt Discusses Stray Voltage


----------



## markore (Dec 7, 2011)

Barjack said:


> And if you don't bond the neutral, you run the risk of a line to case fault going unnoticed.


*And if you do, you run the risk of a neutral (grounded conductor) to case fault going unnoticed, multiple current paths, and EMF.
*
I'm not telling you what to do, just trying to look at the whole picture.

How do you know which side of a stator is "hot" (ungrounded conductor) and which side is "neutral" (ungrounded conductor) in a single phase 2 wire genset? :laughing:

250.26 Conductor to Be Grounded—Alternating-Current
Systems. For ac *premises* wiring systems, the conductor to
be grounded shall be as specified in the following:
*(1) Single-phase, 2-wire — one conductor*
(2) Single-phase, 3-wire — the neutral conductor
(3) Multiphase systems having one wire common to all
phases — the common conductor
(4) Multiphase systems where one phase is grounded —
one phase conductor
(5) Multiphase systems in which one phase is used as in
(2) — the neutral conductor


----------



## Barjack (Mar 28, 2010)

I'm looking at the whole picture too, and I'm not so sure a GFCI would even operate if the frame isn't bonded. Because it's a generator that isn't bonded to anything and isn't grounded, where would the fault current go?


----------



## Meadow (Jan 14, 2011)

If the NEC does not apply to this then I think we would go with a theoretical analysis as to what would be safer/better. Ultimately it would be the manufacturer, however, operating the system floating might have an advantage that they know of. Service continuity, reduced risk of electrocution ect. 



To those wondering the earth would be the frame of the vehicle itself, and bonding to the metal frames would act as the ground rod. The only time the vehicle might benefit from a ground rod is if it gets hit by lightning, but other than that its useless. I doubt anyone would be serving food during a thunderstorm.


----------



## markore (Dec 7, 2011)

Barjack said:


> I'm looking at the whole picture too, and I'm not so sure a GFCI would even operate if the frame isn't bonded. Because it's a generator that isn't bonded to anything and isn't grounded, where would the fault current go?


If you watch the stray voltage video it will help with the voltage drop and potential concepts. A lot of misinformation is out there about how faults actually get cleared and utility line to ground voltage. 

There are a lot of different ways to connect GFI's in this situation that are best entertained in a diagram instead of text. Will come back to this thread tomorrow. Night all and thanks for the fun discussion.


----------



## Barjack (Mar 28, 2010)

Follow this link and watch the video (you may have to download Real Player):

http://www.mikeholt.com/videodisplaynew.php?pageid=4398

Mike Holt himself is unsure of whether to bond the system of a portable generator, and echos my concern that a ground fault would clear if it isn't bonded.

In this case a ground fault would be more like a case fault, but inside the kitchen of a food truck, the floor would probably be connected to the frame and be bonded.


----------



## Dennis Alwon (May 9, 2009)

Wow, I am impressed with the number of responses. Over at mike holt I got 6 responses and 3 were mine.

I admit that I have fallen prey to the concept that electricity returns to ground. It really will only return to the source of the circuit.

I was thinking that the genny could energize the truck frame and if you stepped on the ground you would be picking up the earth and going back to the power company's grounds that are connected to the earth.

I realize that is not the case so if there is a line to case fault the short would not be noticed but the entire vehicle could be energized. I would hate to be the electrician that opens a receptacle thinking the neutral is safe. 

I also believe that if the genset is the only source of power then it is an SEPARATELY DERIVED SYSTEM.

I don't know why the genny isn't bonded. They do say to bond the unit to the body of the vehicle but not to the neutral. Unless my guys meter wasn't working-- I doubt it-- then there was no continuity from equipment grounding conductor and neutrals.

I will call them Monday but it seems the neutral should be bonded


----------



## Dennis Alwon (May 9, 2009)

Interestingly enough the 2014 has redefined sds and it think it clears up that discussion.



> Separately Derived System. An electrical source, other
> than a service, having no direct connection(s) to circuit
> conductors of any other electrical source other than those
> established by grounding and bonding connections.


----------



## 8V71 (Dec 23, 2011)

Dennis Alwon said:


> Wow, I am impressed with the number of responses. Over at mike holt I got 6 responses and 3 were mine.


I think people tend to shy away from these scenarios because it's such a grey area with each method having almost equal plus and minuses.

It may have already been discussed, but is there a transfer switch and shore line?


----------



## Dennis Alwon (May 9, 2009)

8V71 said:


> I think people tend to shy away from these scenarios because it's such a grey area with each method having almost equal plus and minuses.
> 
> It may have already been discussed, but is there a transfer switch and shore line?


No shore or transfer power just the genny


----------



## Barjack (Mar 28, 2010)

I really don't think stray voltage is a factor here BTW.


----------



## 8V71 (Dec 23, 2011)

Dennis Alwon said:


> No shore or transfer power just the genny


I'm looking for a safety factor that would push this one way or another. If the neutral was left unbonded, the GFI's would still work. If there was an unknown line to ground fault and an electrician was touching ground and neutral while working on something the GFI would also take care of that situation.

What about a mechanic working on the vehicle while the generator is running with an unknown line to ground fault? A utility grounded power tool? Would that be a danger?

ETA: I'm not so sure about this one now. That would be like touching line and neutral. _"If there was an unknown line to ground fault and an electrician was touching ground and neutral while working on something the GFI would also take care of that situation."_


----------



## RandyM (Apr 5, 2012)

If it was unbonded and there is a fault between hot and ground then the neutral would be 120 V to ground. 
Not until a second fault between Neutral and ground would it trip a CB. 
Troubleshooting would be a nightmare.


----------



## Barjack (Mar 28, 2010)

A GFCI works because in most cases there exists a second path back to the source other than the neutral (earth, grounded metal, pipes, whatever). In the situation of a food truck, powered by a generator that doesn't have any bonded conductors, there would never be that second path back to the source.


----------



## 8V71 (Dec 23, 2011)

There is a ground though. Wouldn't a GFCI operate the normal way if someone is getting a shock while touching something that is grounded because of current imbalance?

ETA: never mind....I see your point. There would never be a shock potential unless someone touches line and neutral.


----------



## Barjack (Mar 28, 2010)

If there is a separate path back to the source (generator) it would. NOT just the ground by itself.


----------



## Dennis Alwon (May 9, 2009)

A gfci working does not eliminate shock. It helps but not a fail safe


----------



## 8V71 (Dec 23, 2011)

Barjack said:


> If there is a separate path back to the source (generator) it would. NOT just the ground by itself.


Gotcha...I was editing my post when you posted.


----------



## Big John (May 23, 2010)

My thinking on this is that because he has equipment grounds in place, I think an unbonded generator is reasonably safe.

The first ground fault will bond the system (regardless if it occurs in line or neutral) the second ground fault will create a short circuit and the OCPD will clear the fault.

I think do think it's safer and more reliable to put in an intentional bonding jumper, just because the effective operation of the system is more under the electrician's control instead of waiting for accidents to happen.


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> Wow, I am impressed with the number of responses. Over at mike holt I got 6 responses and 3 were mine.
> 
> I admit that I have fallen prey to the concept that electricity returns to ground. It really will only return to the source of the circuit.
> 
> ...




That's the power of ET

The earth in this case would be the truck frame. All power is referenced to that. If a ground fault occurred in a piece of equipment and one was to touch it while standing on earth nothing would happen, but if they were to touch the truck frame with one hand while the other hand was on the faulted equipment or were sitting in the truck while touching the faulted equipment then power would flow through them causing shock. Power would go back through the frame and back to the source that being the neutral bond/wire to frame capitance. However, with the system properly bonded, ie everything has an egc, any fault would be of no danger regardless if the neutral is bonded or not. 


As for the manufacturer wanting the neutral bonded or not bonded to the frame its up to them both have there advantages and disadvantages. One reason for not bonding the neutral would be greatly increased personal safety. If one was to touch the phase or neutral while touching the frame the current that would flow through them would be minimal, only the wire to frame capacitance would provide a return path. Considering the size of the truck it would probably be a few milliamps. The system would have the safety similar to ungrounded power systems used in hospitals. 

Down side is a ground fault would go unnoticed without a ground detector and it would take 2 faults on opposite phases to clear a breaker, possibly both breakers if they operate fast enough. 






8V71 said:


> I think people tend to shy away from these scenarios because it's such a grey area with each method having almost equal plus and minuses.
> 
> It may have already been discussed, but is there a transfer switch and shore line?


 
Yup. Grey area indeed.

In cases like this electrical theory rather than code theory kicks in as to what is the better option.


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> That's the power of ET


 Yep and almost all post we on topic---:thumbsup:



> The earth in this case would be the truck frame.


Exactly and that part is where my brain keeps thinking ground earth-- I understand as I stated earlier but I had a brain fartty




> As for the manufacturer wanting the neutral bonded or not bonded to the frame its up to them both have there advantages and disadvantages. One reason for not bonding the neutral would be greatly increased personal safety. If one was to touch the phase or neutral while touching the frame the current that would flow through them would be minimal, only the wire to frame capacitance would provide a return path. Considering the size of the truck it would probably be a few milliamps. The system would have the safety similar to ungrounded power systems used in hospitals.


I guess for insurance purposes they would rather be covered. It does seem the NEC does not require the neutral to be bonded to the frame as state in 250.34 as Markore quoted.



> Down side is a ground fault would go unnoticed without a ground detector and it would take 2 faults on opposite phases to clear a breaker, possibly both breakers if they operate fast enough.


 This is true but something they will have to live with. I feel better about what we did. Problem is there is no 240V just 120V-- same phase


[In cases like this electrical theory rather than code theory kicks in as to what is the better option.[/QUOTE]

Agreed and thank you and all others for helping in this thread. We had it right to begin with but I didn't trust myself for some reason....:thumbsup:


----------



## markore (Dec 7, 2011)

Barjack said:


> Follow this link and watch the video (you may have to download Real Player):
> 
> http://www.mikeholt.com/videodisplaynew.php?pageid=4398
> 
> ...


Mike Holt is notorious for changing his position on bonding over time, that was why I posted the stray voltage video where he talks about the evolution of his understanding towords one inclusive of more sound fundamentals. 

The fundamentals and drawings they illustrate in the stray voltage video are relevant to this discussion because they show relevant fundamentals and illustrate how you can still relieve a shock even with grounding and bonding, no matter how many ground rods or how thick of bonding jumper you use.

A voltage drop through a lode, long run, or lose connection is enough to cause a difference in potential large enough to shock a human pretty bad, and with vehicles, loose connections are common.
*
Isolation is often a better tactic.

Why are double insulated tools safer than case grounded tools?
Because they provide protection that does not require the proper operation of another device such as a breaker or gfi to clear the fault.
**
Remember the neutral is a current carrying conductor. You do not want current flowing through the chassis of a vehicle or device.
*
As meadow noted if the neutral is not bonded then user hazard would require both a line and neutral fault, and in the event of these two simultaneous faults, the breakers or gfi's would operate normally.* Would you rather find out you have a fault the first time a breaker fails to open and somebody loses their vision, or have the single fault cause no damage and continue to operate safely for years?* The manufacturer's schematic indicates isolation, even between the two neutrals...

To quote the Mike Holt page you linked:
Grounding versus Bonding (Grounded Neutral Conductor Bonding is only required when supplying a building)


> 250.34 Generators—Portable and Vehicle-Mounted
> 
> (A) Portable Generators. The frame of a portable generator isn’t required to be grounded to the earth if: Figure 250–88
> 
> ...


When a generator is powering a building bonding is required because of the likelyhood of parallel paths through water pipes, concrete, or the earth. Mobile vehicles are unlikely to have these physical connections to the earth.

When line conductors and neutral conductors travel different paths outside the same enclosure (faraday cage) raceway or tightly bundled cable then EMF and stray voltage will be induced, this is why old vehicles have tons of ground hum on the speaker systems because the chassis was used to complete the circuit through multiple paths.


----------



## markore (Dec 7, 2011)

Dennis Alwon said:


> We had it right to begin with but I didn't trust myself for some reason....:thumbsup:


Very interested hear back from cummins on their recommendations or if their is additional literature available for that model... what model?


----------



## markore (Dec 7, 2011)

Side question, does double insulated mean line and neutral are both insulated, or both line and neutral are insulated twice, or just the hot is insulated twice?


----------



## markore (Dec 7, 2011)

Big John said:


> My thinking on this is that because he has equipment grounds in place, I think an unbonded generator is reasonably safe.
> 
> The first ground fault will bond the system (regardless if it occurs in line or neutral) the second ground fault will create a short circuit and the OCPD will clear the fault.
> 
> I think do think it's safer and more reliable to put in an intentional bonding jumper, just because the effective operation of the system is more under the electrician's control instead of waiting for accidents to happen.


Thanks for your post. In response to your last part I think that would depend on the type of OCPD's you are using. If you bond the system you are going to be reseting the breakers more often so I would make sure they are the type that actually trip instead of weld closed.

Anybody know of a non-destructive test procedure for non-arc fault breakers that does not void the warranty?


----------



## Barjack (Mar 28, 2010)

You are an engineering student and you're calling out Mike Holt? OK

You use MH videos to make your point yet you denounce them when you don't like what they say. OK

STRAY VOLTAGE will probably never be an issue with Dennis' installation, yet bonding a system conductor will allow for the OCPD system and any GFCI's to operate under fault conditions.


----------



## markore (Dec 7, 2011)

Dennis Alwon said:


> Wow, I am impressed with the number of responses. Over at mike holt I got 6 responses and 3 were mine.


Guess this crew likes Trucks AND Food! :laughing:



Dennis Alwon said:


> I realize that is not the case so if there is a line to case fault the short would not be noticed but the entire vehicle could be energized. I would hate to be the electrician that opens a receptacle thinking the neutral is safe.


Which neutral? :laughing: If you connected the two neutrals then yes there is less isolation from any given load, so you may consider also bonding the frame.
If you trust your breakers to trip then as has been stated you are not forbidden to bond the neutral, just not required.

Since the two neutrals have been combined instead of kept isolated then I see why you are considering bonding the neutral conductor. 
Had you considered bonding it with a disconnect?


----------



## markore (Dec 7, 2011)

Barjack said:


> You are an engineering student and you're calling out Mike Holt? OK
> 
> You use MH videos to make your point yet you denounce them when you don't like what they say. OK
> 
> STRAY VOLTAGE will probably never be an issue with Dennis' installation, yet bonding a system conductor will allow for the OCPD system and any GFCI's to operate under fault conditions.


Did you watch the video? I'm not calling him out on anything, just highlighting his honesty and compassion. He is a good man and a friend and in the video he talks about how his understanding has changed over the years from originally thinking grounding and bonding would fix everything but in reality voltage drop, capacitance, inductance and stray voltage make systems operations much more complicated than the NEC code itself.

It takes honesty and compassion to admit we can still all learn something new everyday, and that in the past we may have clung to some beliefs which are no longer helpful.

I am a master's student and PHD candidate, been in the trade working days and studying nights since 2001, but don't sue me if you blow up yourself trying to follow anyone's advice on here.

Not trying to make any points just that his diagrams and pictures in his free videos are top notch and are good tools for understanding voltage drop in AC systems.

If you have good quality OCPD's and GFI's then there is nothing wrong with bonding everything. Isolation or bonding, its a design decision, just like the decision to bond the two neutrals from the two coils, or not.


----------



## Dennis Alwon (May 9, 2009)

markore said:


> Which neutral? :laughing: If you connected the two neutrals then yes there is less isolation from any given load, so you may consider also bonding the frame.
> If you trust your breakers to trip then as has been stated you are not forbidden to bond the neutral, just not required.
> 
> Since the two neutrals have been combined instead of kept isolated then I see why you are considering bonding the neutral conductor.
> Had you considered bonding it with a disconnect?


If some opens up the panel while the genny is running and there is a line to ground short then touching the panel and the neutral bar would hurt at least.

I had considered bonding the neutral to the can in the panel - first thing I said when the guys got home is did the save the bonding screw--- I explained the bonding possibility earlier- not compliant maybe but this is outside the nec ruling---and may avoid issues later. Not sure of the down side either -- I can't seem to see any


----------



## Barjack (Mar 28, 2010)

I did watch the video. Please explain how stray voltage will affect someone that is in or around this food truck if one of the system conductors is bonded. 

Use small words. I am an electrician, not an engineer.


----------



## chicken steve (Mar 22, 2011)

> The fundamentals and drawings they illustrate in the stray voltage video are relevant to this discussion because they show relevant fundamentals and illustrate how you can still relieve a shock even with grounding and bonding, no matter how many ground rods or how thick of bonding jumper you use.


I learned @ ET from foreign sparkies just how much of a detriment _we _create by over grounding, multiple mbj sds's proximal to each other, etc

Seems the nec is moot on the earths conductibility , while other countries address it 

The perspective continues with SWER systems....

_everything is a noodle_....having bonded the living daylights out of some local farms sheds insight to this

equopotential planes simply provide equal _gradient_, bird (or cow as it may be) on the wire results....

~CS~


----------



## chicken steve (Mar 22, 2011)

Barjack said:


> I did watch the video. Please explain how stray voltage will affect someone that is in or around this food truck if one of the system conductors is bonded.
> 
> Use small words. I am an electrician, not an engineer.


the truck shell becomes part of the return circuit , different potential than that of the patrons standing on the earth next to it

~CS~


----------



## markore (Dec 7, 2011)

Dennis Alwon said:


> If some opens up the panel while the genny is running and there is a line to ground short then touching the panel and the neutral bar would hurt at least.
> 
> I had considered bonding the neutral to the can in the panel - first thing I said when the guys got home is did the save the bonding screw--- I explained the bonding possibility earlier- not compliant maybe but this is outside the nec ruling---and may avoid issues later. Not sure of the down side either -- I can't seem to see any


Have you seen a GFCI breaker with a connection to ground? 
If you connected the load side to the generator chassis, vehicle chassis, and equipment grounding conductor you would have both isolation and fault protection.


----------



## Barjack (Mar 28, 2010)

.......and if it is GFCI protected it will trip. It should be GFCI protected and bonded. I mean stray voltage from some other source.


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> .......and if it is GFCI protected it will trip. It should be GFCI protected and bonded. I mean stray voltage from some other source.


So you think I should bond the neutral at the panel??? Any downside. Gfci should work

To Markore- I have not seen a gfi breaker with a ground connection but they have grounded connections (the neutral)


----------



## Barjack (Mar 28, 2010)

Dennis Alwon said:


> So you think I should bond the neutral at the panel??? Any downside. Gfci should work To Markore- I have not seen a gfi breaker with a ground connection but they have grounded connections (the neutral)


No I just think a system conductor (or two in this case) should be bonded to the frame and there be GFCI protection. Wouldn't you want the frame to be part of the return path, just like you would want any metal not likely to be energized part of the return path of a normal grounded system in the event of a fault?


----------



## Meadow (Jan 14, 2011)

chicken steve said:


> I learned @ ET from foreign sparkies just how much of a detriment _we _create by over grounding, multiple mbj sds's proximal to each other, etc
> 
> Seems the nec is moot on the earths conductibility , while other countries address it
> 
> ...



There is nothing wrong with over grounding/bonding something in terms of stray current/electrical protection ect. Most of the time there is no harm. In places like hospitals its actually a good thing. The harm however comes when a current carrying conductor is bonded to earth more than once. Current will divide between the conductor and everything that's grounded/bonded. Should the connection break between the 2 grounded points it generally goes unnoticed and dumps all the current across ground, earth, metal frames, egc ect. 


Utilities are the biggest offender by far with SWER systems outside of the US and MGN systems in the US. Both systems either intentionally or inadvertently rely on the earth as a continues conductor. Even in California and Europe where its rare to multiply earth a HV neutral its still common practice to earth the LV neutral repeatedly. Anywhere such a system exists a 50 or 60Hz voltage gradient can be picked up across the earth along with very high EMFs. 

Anyways, back to the truck, as long as no parallel current paths exists on the frame there's no issue. The GFI will guarantee a neutral fault in an external cord cap connected appliance will shut it down.


----------



## Barjack (Mar 28, 2010)

chicken steve said:


> the truck shell becomes part of the return circuit , different potential than that of the patrons standing on the earth next to it ~CS~


It could be a different potential anyway. It is isolated from the earth by the tires. Just tell me how the electrons from one source (other than the generator) will sneak into the generator if one of the conductors is bonded. I am only saying that bonding a system conductor of the genny doesn't make any more of a hazard as far as stray voltage is concerned, but will operate as a safe system.


----------



## chicken steve (Mar 22, 2011)

meadow said:


> > There is nothing wrong with over grounding/bonding something in terms of stray current/electrical protection ect. Most of the time there is no harm. In places like hospitals its actually a good thing. *The harm however comes when a current carrying conductor is bonded to earth more than once*. Current will divide between the conductor and everything that's grounded/bonded. Should the connection break between the 2 grounded points it generally goes unnoticed and dumps all the current across ground, earth, metal frames, egc ect.
> >
> >
> > Utilities are the biggest offender by far with SWER systems outside of the US and *MGN systems in the US*. Both systems either intentionally or inadvertently rely on the earth as a continues conductor. Even in California and Europe where its rare to multiply earth a HV neutral its still common practice to earth the LV neutral repeatedly. Anywhere such a system exists a 50 or 60Hz voltage gradient can be picked up across the earth along with very high EMFs.
> ...


----------



## chicken steve (Mar 22, 2011)

Barjack said:


> It could be a different potential anyway. It is isolated from the earth by the tires. Just tell me how the electrons from one source (other than the generator) will sneak into the generator if one of the conductors is bonded. I am only saying that bonding a system conductor of the genny doesn't make any more of a hazard as far as stray voltage is concerned, but will operate as a safe system.


I don't believe, short of the food truck backing into an xformer, that another source will introduce itself to the genny Barjack

All current would seek it's source, a circle so to speak

I guess that circle could be extended to those touching the truck during a wet day.....under the right conditions, maybe....

~CS~


----------



## markore (Dec 7, 2011)

Is the genset the 6 HDKAV/41934?
https://powersuite.cummins.com/PS5/...nary_Asset/pdf/Consumer/specsheets/a-1486.pdf

Full list

What brand of panel has been installed?
Is there room for a second panel for the second coil?


----------



## Dennis Alwon (May 9, 2009)

markore said:


> Is the genset the 6 HDKAV/41934?
> https://powersuite.cummins.com/PS5/...nary_Asset/pdf/Consumer/specsheets/a-1486.pdf
> 
> Full list
> ...


Job is done-- I ain't changing much if anything at all..

The genny is a HGJAE-2132 120V 2p 30 breaker listed at 58 amps

Panel is a main lug GE panel (not sure why that matters)-- remember no transfer switch is involved.

I suppose there may be room for 2 panel but why would I do that? Seems a bit much when I can basically accomplish the same with one panel.


----------



## Dennis Alwon (May 9, 2009)

Hey I pulled out an old Federal Pacific Panel with 3 bona fide FP gfci breakers


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> Job is done-- I ain't changing much if anything at all..
> 
> The genny is a HGJAE-2132 120V 2p 30 breaker listed at 58 amps
> 
> ...



If the panel is 125 amps rated your ok. But if you have a 30 amp rated panel the neutral bus might overload (at least Ive been told but don't know well enough) since normally the current would be cancelling instead off adding. ie, both 30 amp hot buss bars would be ok, but the neutral bus will not be if 30 amp rated as well.


----------



## Barjack (Mar 28, 2010)

Dennis Alwon said:


> Hey I pulled out an old Federal Pacific Panel with 3 bona fide FP gfci breakers


Worth their weight in gold......if they work. Any way to tell if they will trip under overload?


----------



## markore (Dec 7, 2011)

meadow said:


> If the panel is 125 amps rated your ok. But if you have a 30 amp rated panel the neutral bus might overload (at least Ive been told but don't know well enough) since normally the current would be cancelling instead off adding. ie, both 30 amp hot buss bars would be ok, but the neutral bus will not be if 30 amp rated as well.


This was why I was asking. If you are going to stick with one panel and not bond the ground I would float a second 30A+ neutral bar completely separate and keep the two neutrals from each coil separate if you are going the isolation route with no bonding.

If you are going the bonded route it sounds like from meadow the 125A neutral bar is fine.
Its a little unclear on the manufacturers schematic if the two neutrals are already connected internally or not.

Either way sounds fine, isolation or bonded; would sure be nice to label or make the work look obvious so it's clear for the next guy which choice you made.
As big john noted earlier, isolation would give you the ability to keep using one coil if the other was damaged, but bonding would make the GFI's trip like you would normally expect, no matter which conductor faults...

HGJAE-2132
https://powersuite.cummins.com/PS5/...nary_Asset/pdf/Consumer/specsheets/a-1440.pdf

Hope to hear back what cummins has to say after you talk to them and also who makes the breakers CB1 and CB2 installed on the generator itself.....


----------



## markore (Dec 7, 2011)

Here is a whitepaper from cummins discussing paralleling and isolated bus effects on loading/coil voltage droop:
http://www.cumminspowerdocs.com/literature/technicalpapers/PT-9017-P3-Dissimilar-en.pdf


----------



## markore (Dec 7, 2011)

Here is a whitepaper from cummins on ungrounded system operation:

Look at page 3 and 4
http://www.cumminspowerdocs.com/literature/technicalpapers/PT-6005-GroundingAC-1-en.pdf
Ground fault protection and switching the neutral
http://www.cumminspowerdocs.com/literature/technicalpapers/PT-6006-GroundingAC-2-en.pdf



> Ungrounded
> A power system not having any intentional connection
> to ground is referred to as an ungrounded system.
> However, *because of the capacitive coupling between
> ...


Barjack understand this paragraph and you will start to understand capacitive coupling and inductive stray voltage. I wish I could explain it simply on here but honestly I don't understand the subject well enough myself to explain it in a simpler way.

The most straightforward thing I can say is to be careful around neutral conductors even when the line breakers are off because voltage drop from other loads in the system or the neutral cable itself, capacitive coupling and inductive stray voltage will often still create a very measurable voltage on the neutral if you have sensitive equipment. As mike holt describes in his video and I have personally experienced can be painful and surprising enough to make you lose your grip on a ladder.



> Summary
> The method of system grounding used has a significant
> effect on the continuity of power to critical loads under
> ground fault conditions. Solidly grounded systems
> ...


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> Worth their weight in gold......if they work. Any way to tell if they will trip under overload?


I have the panel I guess I could experiment but I doubt I would ever use it. I probably will give them to ec's here that need them


----------



## Barjack (Mar 28, 2010)

markore said:


> Here is a whitepaper from cummins on ungrounded system operation:
> 
> Look at page 3 and 4
> http://www.cumminspowerdocs.com/literature/technicalpapers/PT-6005-GroundingAC-1-en.pdf
> ...



First, I never said anything about grounding. I only said that he should bond one of the system conductors to the generator frame.

Second, I understand what neutrals are and how they should be treated. In this case, they really aren't neutrals, just the other sides of two single phase circuits. Sometimes its just easier to say neutral.

Third, those PDF's don't say anything about bonding things in an ungrounded system. It only says just to let the first fault happen, then maybe when there is a second fault, the breaker might trip.


----------



## RandyM (Apr 5, 2012)

Are there any appliances that may be plugged in mind a possible high voltage on the "neutral" to ground?


----------



## Dennis Alwon (May 9, 2009)

RandyM said:


> Are there any appliances that may be plugged in mind a possible high voltage on the "neutral" to ground?


All the appliances are plugged in. Even the custom water heater is 120V with cord and plug. The generator is the only thing that has direct wiring to it.


----------



## markore (Dec 7, 2011)

Barjack said:


> First, I never said anything about grounding. I only said that he should bond one of the system conductors to the generator frame.
> 
> Second, I understand what neutrals are and how they should be treated. In this case, they really aren't neutrals, just the other sides of two single phase circuits. Sometimes its just easier to say neutral.
> 
> Third, those PDF's don't say anything about bonding things in an ungrounded system. It only says just to let the first fault happen, then maybe when there is a second fault, the breaker might trip.


All very valid and good points. Thanks for the discussion.


----------



## Barjack (Mar 28, 2010)

FWIW, this is OSHA's requirements for portable generators on construction sites. 

http://oshaprofessor.com/Portable Generators and OSHA Construction Standards 3-05.pdf

They do consider a PG an SDS. 

They do not disallow the connection of one conductor of a two wire system to the frame, but say that if you do, there must be GFCI protection.


----------



## Dennis Alwon (May 9, 2009)

Okay, you remember me not being able to wrap my brains around the fact that electricity will only go back to its source. Well I am confused again.

We took a Honda Generator that has wheels and placed it on a piece of plywood about 50 feet from the house. Took a meter a got 80 V from the hot of the generator to earth ground- stuck the probe in the earth. 

So why?

This seems to tell me someone can get shocked from the truck that was the original topic of this thread.


----------



## Barjack (Mar 28, 2010)

I'm intrigued. What does your wiggy say? If a solenoid style tester doesn't read anything, I'd say its phantom voltage. If it's real, 80v might be enough to light a lamp so you could try that.


----------



## Barjack (Mar 28, 2010)

Also, do you mean you took one probe to the hot, and the other to earth? …and the generator frame is not bonded to anything?


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> Also, do you mean you took one probe to the hot, and the other to earth? …and the generator frame is not bonded to anything?


Yes-- I actually didn't do it but my friend who is an ec did it for me since he had the genny. He used a digital meter I am sure-- generator was not bonded to earth hence the rubber tires and plywood to keep it off the earth.


----------



## Dennis Alwon (May 9, 2009)

I also wondered whether a bulb or anything would light -- I'll get him to try that.


----------



## Barjack (Mar 28, 2010)

Dennis Alwon said:


> Yes-- I actually didn't do it but my friend who is an ec did it for me since he had the genny. He used a digital meter I am sure-- generator was not bonded to earth hence the rubber tires and plywood to keep it off the earth.


I'm interested to know what a wiggy says.


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> Okay, you remember me not being able to wrap my brains around the fact that electricity will only go back to its source. Well I am confused again.
> 
> We took a Honda Generator that has wheels and placed it on a piece of plywood about 50 feet from the house. Took a meter a got 80 V from the hot of the generator to earth ground- stuck the probe in the earth.
> 
> ...


Generator frame grounded and capacitive coupling to earth?


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> I'm interested to know what a wiggy says.


I have a solenoid tester but he does not so I will have to try that


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> Generator frame grounded and capacitive coupling to earth?


The generator may as well be hanging in the air-- no earth connection. Are you asking if the frame is grounded to the neutral? Not sure but why would that have any effect on the voltage to earth.


----------



## frenchelectrican (Mar 15, 2007)

Dennis Alwon said:


> I also wondered whether a bulb or anything would light -- I'll get him to try that.


If LED yeah it may but conventail bulb naw I doubt it depending on how much restiance you have on the earth if wet ., yeah you may light it up some degrees but not full bightness for sure.

I alleady try that with the European spec'ed units over here in France and it was kinda instering I know Americiane spec'ed verison are wired the same manner on Honda units and their netural connection on stator is floated. ( most of the time.) 

Merci,
Marc


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> The generator may as well be hanging in the air-- no earth connection. Are you asking if the frame is grounded to the neutral? Not sure but why would that have any effect on the voltage to earth.


If the frame is grounded to the neutral the frame is basically like a capacitor plate. The earth around it is the second plate.


----------



## Barjack (Mar 28, 2010)

So would someone receive a shock if they touch the hot and ground?


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> So would someone receive a shock if they touch the hot and ground?


That is my question.... It appears so but maybe not. My friend said he will try the bulb thing before our local meeting tomorrow night.


----------



## Dennis Alwon (May 9, 2009)

meadow said:


> If the frame is grounded to the neutral the frame is basically like a capacitor plate. The earth around it is the second plate.


And being isolated would not matter? How far away would you have to go to get away from that?


----------



## frenchelectrican (Mar 15, 2007)

Barjack said:


> So would someone receive a shock if they touch the hot and ground?


Oui ou Non depending on the earth itself so if the condtions is correct like a earth is very wet then oui ya will get it but super dry earth then no.

Merci,
Marc


----------



## Barjack (Mar 28, 2010)

I don't know if you saw my earlier post, but OSHA requires GFCI protection IF the frame is bonded to the "neutral".


----------



## Dennis Alwon (May 9, 2009)

frenchelectrican said:


> Oui ou Non depending on the earth itself so if the condtions is correct like a earth is very wet then oui ya will get it but super dry earth then no.
> 
> Merci,
> Marc


Marc, we are talking about how is it possible to go to another systems ground. Electricity should only go back to its source. Take two battery and connect from the positive of one and then to the negative of the other- I doubt you will read anything


----------



## Dennis Alwon (May 9, 2009)

Barjack said:


> I don't know if you saw my earlier post, but OSHA requires GFCI protection IF the frame is bonded to the "neutral".


I am sure there is a gfci on the unit


----------



## chicken steve (Mar 22, 2011)

meadow said:


> If the frame is grounded to the neutral the frame is basically like a capacitor plate. The earth around it is the second plate.


but what would be the dif in potential between them Meadow?

~CS~


----------



## frenchelectrican (Mar 15, 2007)

Dennis Alwon said:


> Marc, we are talking about how is it possible to go to another systems ground. Electricity should only go back to its source. Take two battery and connect from the positive of one and then to the negative of the other- I doubt you will read anything


That is true Dennis., but it will always go back to the oringal source of what it generated ( outgoing source ).

Merci,
Marc


----------



## Meadow (Jan 14, 2011)

chicken steve said:


> but what would be the dif in potential between them Meadow?
> 
> ~CS~


No idea, but if you knew the micro farads you should have a rough idea. I doubt its enough to light a bulb even a LED, but a high impedance meter will read nearly anything under any condition. A few feet or floating THHN in conduit around an energized wire will give a reading.


----------



## Barjack (Mar 28, 2010)

frenchelectrican said:


> That is true Dennis., but it will always go back to the oringal source of what it generated ( outgoing source ). Merci, Marc


So it goes to earth, then back through what path?


----------



## Dennis Alwon (May 9, 2009)

Okay here is what he found. He took a socket with a 40 watt reflector bulb and got nothing from the generator hot to the earth ground nor to the genny frame so I guess it is not bonded. Yes, he did make sure the bulb was working.

He also tested the voltage from one side of the socket to earth and got 60V but when he put himself between the earth and the socket he did not feel anything.


----------



## Meadow (Jan 14, 2011)

Dennis Alwon said:


> Okay here is what he found. He took a socket with a 40 watt reflector bulb and got nothing from the generator hot to the earth ground nor to the genny frame so I guess it is not bonded. Yes, he did make sure the bulb was working.
> 
> He also tested the voltage from one side of the socket to earth and got 60V but when he put himself between the earth and the socket he did not feel anything.


Sounds like what would normally take place. Even though the neutral may be physically floating both hot and neutral are floating capacitively to the frame and the frame to the earth. Similar to 2 pieces of THHN in a metal conduit. 

BTW, 60 volts is about correct since when both hot and neutral are floating a high impedance meter gives an artificial neutral reference formed by the two if Im keeping it simple. 


IE, a 240 ungrounded delta gives about 138, and at 480 about 277. Same with a hospital ungrounded system with no faults about 60 volts at 120. However ground a phase and you will get zero on the grounded wire yet full phase voltage on the none grounded wires to ground. 

I would theorize if the neutral is bonded to the frame there would be 120 volts to earth or something close.


----------



## Dennis Alwon (May 9, 2009)

Thank you all-- I knew something wasn't right when he told me he had 80V. :thumbsup: 80v yes but not really as the risk of shock is not there.


----------

