# Proper Grounding?



## reddog552 (Oct 11, 2007)

I have just instaled a 3 Phase system supplying Tanning beds. I have 277/480 3 phase 100amp supplying a 150 kva x-former Secondary is 120/240 3phase,Delta to delta Xformer.This feeds a dedicated pannel 200 amp.The beds are fed 15 to 60 amps 120/240 3 phase.Here is the problem Inspector isnt shure about ground.I am connected to the main lug in the 1000 amp 277/480 cabinet,there is a second bonding in X-former Then tied into the 200 amp pannel. The beds are fed with a #6 ground wire.Am I properly grounded?


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## nitro71 (Sep 17, 2009)

You're not sure and the inspector isn't sure? I'd be nervous using those tanning beds..

If you sized your EGC's correctly it sounds like a good install. Did you establish a GEC on the secondary side of your transformer?

Is your ground connected to XO on the transformer? Either at your first disconnect or in the transformer?


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## RIVETER (Sep 26, 2009)

*Grounding*

Tell us all what you think grounding is ...in the first place.


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## Speedy Petey (Jan 10, 2007)

reddog552 said:


> .........The beds are fed 15 to 60 amps 120/240 3 phase.........
> The beds are fed with a #6 ground wire.Am I properly grounded?


So you ran a #6 ground for a 15A circuit?


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## reddog552 (Oct 11, 2007)

The X-former is a DELTA/DELTA NO HO or XO, not needed dedicated box marked NO NETURAL.I have a # 6 Ground wire ran from switch gear to X-former Case -Core ground this is continued to the dedicated panel (3 phase no netural).labeled this way.Ground in box is bonded, The feeder Ckts. range from 15- 60 amps. All runs are done in emt. #6 x 3 and a #10 green to a disconect,ground lug bond.This is set up this way because the switch the beds regulary.


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## McClary’s Electrical (Feb 21, 2009)

reddog552 said:


> The X-former is a DELTA/DELTA NO HO or XO, not needed dedicated box marked NO NETURAL.I have a # 6 Ground wire ran from switch gear to X-former Case -Core ground this is continued to the dedicated panel (3 phase no netural).labeled this way.Ground in box is bonded, The feeder Ckts. range from 15- 60 amps. All runs are done in emt. #6 x 3 and a #10 green to a disconect,ground lug bond.This is set up this way because the switch the beds regulary.


 
You are compliant, and actually redundant. You could have done away with the #10.


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## nitro71 (Sep 17, 2009)

Without a neutral point on the transformer what causes the breaker to trip if a fault occurs? Is there GFI protection?


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## brian john (Mar 11, 2007)

reddog552 said:


> The X-former is a DELTA/DELTA NO HO or XO, not needed dedicated box marked NO NETURAL.I have a # 6 Ground wire ran from switch gear to X-former Case -Core ground this is continued to the dedicated panel (3 phase no netural).labeled this way.Ground in box is bonded, The feeder Ckts. range from 15- 60 amps. All runs are done in emt. #6 x 3 and a #10 green to a disconect,ground lug bond.This is set up this way because the switch the beds regulary.


 
Somewhere either you or I am confused.

The transformer is Delat Delta?

That would be 480 Primary No Neutral H1, H2, H3

120/240 secondary with X1, X2, X3 and X6?

Other wise you I do not ssee how you derivee 240/120 from a delta secondary.

X6 is a center tap and is to be grounded per thje NEC.

http://www.solahevidutysales.com/pdf/transformers/GenPurpose.pdf


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## reddog552 (Oct 11, 2007)

*Xo ho*

This transformer has only H1-H2-H3 X1-X2- X3 connections no neutral lug. this is a ballanced 3 phase load .I Have heard of corner ground 3 phase delta X-formers,which I could do.But I have no need of a grounded cond.


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## RePhase277 (Feb 5, 2008)

reddog552 said:


> This transformer has only H1-H2-H3 X1-X2- X3 connections no neutral lug. this is a ballanced 3 phase load .I Have heard of corner ground 3 phase delta X-formers,which I could do.But I have no need of a grounded cond.


Then why do you say it is 120/240 secondary? If it is delta/delta, then the only voltage available from the secondary will be 240 V, unless you have X6 that center-taps one of the coils to get 120.


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## nitro71 (Sep 17, 2009)

My question still stands. I'm not a expert at all types of transformers but unless it's a ungrounded system there has to be a way to bond the transformer windings to your ground system on the secondary side. That's the main thing about your install that concerns me. If there is a fault to ground will the breakers trip protecting the bed.


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## reddog552 (Oct 11, 2007)

*Update*

I have What I mistakenly called 3 phase 120/240 Not. I have 120 V 3 phase. Being a true delta 3 phase NO neutral,this is a balanced Ckt.True 3 phase ckts need no Grounded leg. Look it up


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## nitro71 (Sep 17, 2009)

No one is saying you need a neutral but you DON't have a ungrounded system. You better have a grounded system. You look it up in your book, since it's your clients that WILL be suing YOU if someone is injured due to your install.


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## RIVETER (Sep 26, 2009)

*Proper Grounding*



reddog552 said:


> I have just instaled a 3 Phase system supplying Tanning beds. I have 277/480 3 phase 100amp supplying a 150 kva x-former Secondary is 120/240 3phase,Delta to delta Xformer.This feeds a dedicated pannel 200 amp.The beds are fed 15 to 60 amps 120/240 3 phase.Here is the problem Inspector isnt shure about ground.I am connected to the main lug in the 1000 amp 277/480 cabinet,there is a second bonding in X-former Then tied into the 200 amp pannel. The beds are fed with a #6 ground wire.Am I properly grounded?


The bottom line is that you should know if you are properly grounded before the inspector gets there. You cannot blame him/her.


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## reddog552 (Oct 11, 2007)

*Grouded sxstem*

Thats what I saying Inspecter dosrnt know his stuff. My install meet s all requirments. I have a grounding cond. and a grounded conductor Which a TRUE 3 phase has.


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## RePhase277 (Feb 5, 2008)

The question is, regardless of voltage, how is the delta secondary grounded? So far it sounds like the only ground is coming from the 480/277 panel. Unless the secondary has a center tap that is grounded, or one of the phases is grounded, you are not compliant.


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## reddog552 (Oct 11, 2007)

(Ico) Capacitive Reactance.


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## brian john (Mar 11, 2007)

reddog552 said:


> I have What I mistakenly called 3 phase 120/240 Not. I have 120 V 3 phase. Being a true delta 3 phase NO neutral,this is a balanced Ckt.True 3 phase ckts need no Grounded leg. Look it up


Can you give me the manufacture and model number PLEASE. Because none of this makes sense 120 VAC 3 phase delta??????????????

If indeed you have a delta/delta 480 to 240 VAC you STILL need to ground one leg as in CORNER GROUNDED delta.

There is no way in heck you want to be associated with a consumer product that is connected to an ungrounded system.


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## adnoh (Dec 10, 2009)

It sure sound like you have an ungrounded system on you secondary. I do believe if you intend to use an ungrounded system it will require phase monitors in case of first phase fault. 

If you carried your Equipment grounding conductor from the switch board ( 480 primary) threw the transformer and grounded the case of the transfer and did not ground a phase or a mid point of a phase on the secondary side via a GEC. It is for sure an ungrounded system. Using an ungrounded system here could be very dangerous for the application.

Did you use delta 240 breakers for over current devices in the panel board. Read the rule for grounding an ungrounded system. Did you size your AIC rating for the equipment. This sound like recipe for burn down or rupture of the secondary overcurrent devices under phase to phase fault.


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## nolabama (Oct 3, 2007)

What is gonna happen if a phase faults to ground in what this guy is describing. Is this one of those fancy systems that takes two ground faults to open a breaker? And correct me if I am wrong but tanning beds are where people lie down nearly nekkid surrounded by light bulbs that run on 'lectricity?


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## brian john (Mar 11, 2007)

nolabama said:


> What is gonna happen if a phase faults to ground in what this guy is describing. Is this one of those fancy systems that takes two ground faults to open a breaker? And correct me if I am wrong but tanning beds are where people lie down nearly nekkid surrounded by light bulbs that run on 'lectricity?



In an ungrounded system the first fault is commonly referred to as free because now you have a grounded system. No trips on the first fault.


Now if you do not have ground alarms you will not know you have a fault to ground until you measure for it for any reason or the second fault occurs.


The NEC requires the system to be grounded or ground alarms need to be installed.


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## adnoh (Dec 10, 2009)

I forgot to add, I do belive #4 would be the proper size since the grounding conductor is ran back to the main equipment which would make it grounding elctrode conductor for an ungrounded system and shall be sized by the largest service condustor. The service disconecting means for the new sepertly derived system is require to have grounding electrode conductor. Still think an ungrounded in this application is a viloation based on it's premies wiring and code states one phase shall be grounded. If there was one phase fault on the new secondary if left ungrounded it may trip the ground fault in the 1000 amp switch gear.


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## adnoh (Dec 10, 2009)

True on first fault as free but keep in mind the first fault puts voltage on the equipment ground back to a primary grounded system MBJ. Wonder how all those grounded outlets would like that voltage and current if there was nothig to stop it. Even if some some dumb reason the groundng was islaoted on the secondary side ( all in pvc) and not attched to EGC and or GEC the potentioal difference between them in a first phase would most likely kill someone. Good reseon to ground the secondary b- phase or better yet change the tranformer to a Y and just run an properly sized grounded conductor even if it isnt used. I have installed my boost tans for older applications. Now think about having two system in that premise. Hope no one is layinghte bed and reaches over and turnes up the radio or hits a switch to turn off the lights. in a first phase ( free ) fault. Wonder what burning sun tan oil smeels like. I think the 200 amp ungrounded delta and even a cornor grounded delta secondary for the application is a bad one. Just think if a repair tech trouble shooting the cornor grounded delta which usally have subdivide single phase ballest on the insde of the bed.

Just my thoughts on it.


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## brian john (Mar 11, 2007)

adnoh said:


> True on first fault as free but keep in mind the first fault puts voltage on the equipment ground back to a primary grounded system MBJ. Wonder how all those grounded outlets would like that voltage and current if there was nothig to stop it. Even if some some dumb reason the groundng was islaoted on the secondary side ( all in pvc) and not attched to EGC and or GEC the potentioal difference between them in a first phase would most likely kill someone. Good reseon to ground the secondary b- phase or better yet change the tranformer to a Y and just run an properly sized grounded conductor even if it isnt used. I have installed my boost tans for older applications. Now think about having two system in that premise. Hope no one is layinghte bed and reaches over and turnes up the radio or hits a switch to turn off the lights. in a first phase ( free ) fault. Wonder what burning sun tan oil smeels like. I think the 200 amp ungrounded delta and even a cornor grounded delta secondary for the application is a bad one. Just think if a repair tech trouble shooting the cornor grounded delta which usally have subdivide single phase ballest on the insde of the bed.
> 
> Just my thoughts on it.


If they are separate systems which they must be to have one of the systems ungrounded. NO HARM NO FOUL, nothing, done all the time, works and that's the truth.


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## scruffy (Aug 7, 2009)

reddog552 said:


> Thats what I saying Inspecter dosrnt know his stuff. My install meet s all requirments. I have a grounding cond. and a grounded conductor Which a TRUE 3 phase has.


 no matter what all trx have to be grounded for faults you should know this.......you shoulda pulled in a ground conductor from your where your source is when feeding the prime side of the TRX


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## DipsyDoodleDandy (Dec 21, 2009)

*Tanning Beds*

How the hell many tanning beds are in this place??? 1000 amp 3 phase? 
Was this an old machine warehouse or something? Is there 3 wires total coming from utility pole? Why don't you just set another service next to that service if they can afford. Even if it's a little 100 or 200 amp single phase with grounded conductor and make it safe. Take some pics...and get back..
What' the address? I'll go take a look.


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## reddog552 (Oct 11, 2007)

*Tanning beds*

The building is app. 900,000 Sq. ft. Broken up into 2 (stores). 1000 amp 480 3phase main Going to a 1000 amp Cabinent. this feeds Hvac and 2 -250 kva 480-120/240 V 3phase Xformer with a grounded cond each xformer feeds a 3 phase 400amp panel.lighting& recepticle are fed from these. I dont know what U think these beds are (Metal boxes) they are state of the art systems. Fully protected with internal ground fault,phase monerting systems.Built in air cond,aroma dispersal system,mp3 players hookup. NO bare metal parts Totaly encased in acrilic fastened with plastic connectors.


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## DipsyDoodleDandy (Dec 21, 2009)

*Main*

It wasn't me talking about electrocution in beds. My main question was is it 3 wires into main 1000 amp or 4 wires? Just curious.


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## Dennis Alwon (May 9, 2009)

DipsyDoodleDandy said:


> It wasn't me talking about electrocution in beds. My main question was is it 3 wires into main 1000 amp or 4 wires? Just curious.


If it is 3 phase service then there has to be 4 wires coming in from the utility. A neutral must be supplied at every service. art. 250.24(C)


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## Bob Badger (Apr 19, 2009)

Dennis Alwon said:


> If it is 3 phase service then there has to be 4 wires coming in from the utility. A neutral must be supplied at every service. art. 250.24(C)



Not exactly, you only have to bring the grounded conductor if used. You could have a straight three phase corner grounded service or a straight 3 phase ungrounded service, either would be just three wires from utility to service disconnecting means.


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## NolaTigaBait (Oct 19, 2008)

Bob Badger said:


> Not exactly, you only have to bring the grounded conductor if used. You could have a straight three phase corner grounded service or a straight 3 phase ungrounded service, either would be just three wires from utility to service disconnecting means.


I asked this the other day. What if I have a 3phase high leg and a 200 amp 1phase service. Do i need to bring a grounded conductor to each service, even though it's not need at the 3 phase? What's the code reference?


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## DipsyDoodleDandy (Dec 21, 2009)

*Grounded*

Bob's right. We are on a job now with a straight 3 phase ungrounded service. Our local utility company still lets a few people here and there keep it if it's up and active or recently removed. They are not allowed as new service though around here. Try to find out if it's 3 or 4 wires coming into the main if you can and get back.


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## reddog552 (Oct 11, 2007)

Main service is 4 wire


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## raider1 (Jan 22, 2007)

NolaTigaBait said:


> I asked this the other day. What if I have a 3phase high leg and a 200 amp 1phase service. Do i need to bring a grounded conductor to each service, even though it's not need at the 3 phase? What's the code reference?


To have a 3 phase system with a high leg would require that you have a center tapped delta system which would have a grounded conductor.

A delta corner grounded or ungrounded system would not have a high leg.

250.24(C) requires that when a system is grounded at any point then the grounded conductor(s) shall be run to each service disconnecting means.

Chris


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## raider1 (Jan 22, 2007)

Bob Badger said:


> Not exactly, you only have to bring the grounded conductor if used. You could have a straight three phase corner grounded service or a straight 3 phase ungrounded service, either would be just three wires from utility to service disconnecting means.


Correct, but if it was a corner grounded system then one of the phase wires would then become a grounded conductor, and hence you would be bringing a grounded conductor to the service.

Chris


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## NolaTigaBait (Oct 19, 2008)

raider1 said:


> To have a 3 phase system with a high leg would require that you have a center tapped delta system which would have a grounded conductor.
> 
> A delta corner grounded or ungrounded system would not have a high leg.
> 
> ...


Ok, thanks for the clarification.


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## Dennis Alwon (May 9, 2009)

Bob is correct but somewhere at the building there needs to be an ungrounded conductor. I was not thinking more than one service for a building. Almost every building requires one but I suppose there may be some that don't


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## RePhase277 (Feb 5, 2008)

A grounded conductor need not be present in a circuit or feeder fed downstream of the main, but how can a grounded service be dropped with no grounded conductor? I mean, what is the MBJ going to tie into that completes the ground fault circuit path? I've dealt with pure ungrounded systems before, but I don't think I have ever seen a grounded service at the pole, and no grounded conductor in the drop.


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