# A motor starter?



## IBEW191

Why is the neutral the one we cut out in and overload situation? ie normally closed contacts go to A2 on the contactor coil.


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## lefleuron

I dont quite understand what you are asking.

Are you wondering why we run from A2 down to the N.C. through the overloads?


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## IBEW191

lefleuron said:


> I dont quite understand what you are asking.
> 
> Are you wondering why we run from A2 down to the N.C. through the overloads?


 Yes.


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## varmit

I will make a stab at what I THINK that you are asking: 

One side of the control circuit, the neutral on a 120 VAC controls, is routed through the NC contact on the overload relay and then to one side of the coil. This NC contact will open when a over current situation causes the overload to trip. This will open the circuit to the coil and drop out the starter contactor and hopefully, save the motor from potential damage.


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## IBEW191

varmit said:


> I will make a stab at what I THINK that you are asking:
> 
> One side of the control circuit, the neutral on a 120 VAC controls, is routed through the NC contact on the overload relay and then to one side of the coil. This NC contact will open when a over current situation causes the overload to trip. This will open the circuit to the coil and drop out the starter contactor and hopefully, save the motor from potential damage.


 Exactly. Why the neutral though and not the hot? I have been trying to think of why and cant come up with an answer. This particular circuit was electronic OL.


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## varmit

IBEW191 said:


> Exactly. Why the neutral though and not the hot? I have been trying to think of why and cant come up with an answer. This particular circuit was electronic OL.


On a standard 120 VAC control push button type control circuit, the neutral is routed through the overload relay and then to the coil because the "hot" wire is routed through the control devices ( push buttons, selector switches, ect.) and then to the starter. It is normally a code violation to switch the "neutral", but it is allowed to route the grounded conductor through the overload- but not normally through other control devices. 

On many PLC controlled systems, the overload contact is wired to a PLC input, and not the coil. On an overload, the PLC logic will drop out the coil.


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## Big John

I don't know why folks do that, but I think most guys keep doing it because it's just common practice. Why does everyone flex into transformers? There's really no good reason, it's just always been done that way.

Every once in a blue moon I'll see hot switched by the OL; I've been tempted to start wiring them like that myself.

-John


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## varmit

Yep, it's one of those "We have always done it that way before" sort of things. Back in the "Stone Age", when the control power was tapped directly from the top of the starter, from the incoming lines, the starters came with one control wire connected to the center "B" phase and running through the overload contact and on to one side of the coil. The other control wire originated at the incoming "A" phase, at the top of the starter, and ran through whatever control devices were used. It could get really "exciting" checking multiple 480 volt control circuits in a control panel. I am glad that I only see this setup once in a while these days.


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## sparky105

Our HVAC guys always wire through the o.l's first then the safeties then the coil. Use to drive me nuts trouble shooting now I do it :no: and that really drives me nuts.:blink:


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## IBEW191

Big John said:


> I don't know why folks do that, but I think most guys keep doing it because it's just common practice. Why does everyone flex into transformers? There's really no good reason, it's just always been done that way.
> 
> Every once in a blue moon I'll see hot switched by the OL; I've been tempted to start wiring them like that myself.
> 
> -John


 Iv wondered that to! :laughing:


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## RIVETER

varmit said:


> On a standard 120 VAC control push button type control circuit, the neutral is routed through the overload relay and then to the coil because the "hot" wire is routed through the control devices ( push buttons, selector switches, ect.) and then to the starter. It is normally a code violation to switch the "neutral", but it is allowed to route the grounded conductor through the overload- but not normally through other control devices.
> 
> On many PLC controlled systems, the overload contact is wired to a PLC input, and not the coil. On an overload, the PLC logic will drop out the coil.


When routing the common/neutral through the overload contacts you are not switching them...or at least that is not the common concept. When something is "SWITCHED", it typically is switched on a normal basis.


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## nitro71

You're not really putting the OL on the neutral. You're just putting it on the tale end of the ungrounded conductor before everything connects to the neutral or L2 or L3.


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## don_resqcapt19

nitro71 said:


> You're not really putting the OL on the neutral. You're just putting it on the tale end of the ungrounded conductor before everything connects to the neutral or L2 or L3.


I have never seen one wired like that. I have seen a few wired with the overload relay contact first on the left side of the ladder diagram, but the vast majority have the overload relay contact connected between the coil and the neutral on the right side of the ladder diagram.
Note that if you are using the switched side of the overload relay to connect to something that is exterior to the starter enclosure the code does not permit the overload relay contact to be in the grounded conductor of the control circuit. 430.74


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## erics37

nitro71 said:


> You're not really putting the OL on the neutral. You're just putting it on the tale end of the ungrounded conductor before everything connects to the neutral or L2 or L3.


The wire going through the OL relay's N.C. contact is from the load side of the starter coil, through the contact, and back to L2. It's the wire from the load side of the load, so once the coil is energized and the control voltage is dropped across it, the conductor from there through the OLs wouldn't be the ungrounded anymore unless it was open.

(I didn't draw this, I just googled it):


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## John Valdes

Does it really matter? I mean the concept of the OLR is to drop out the contactor. Who cares how its done. As long as the control circuit author draws it as it is, whats the big deal?
In the drawing above you could put the OL contact between L1 and the stop button. It would work and it would be documented.


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## Wireman191

John Valdes said:


> Does it really matter? I mean the concept of the OLR is to drop out the contactor. Who cares how its done. As long as the control circuit author draws it as it is, whats the big deal?
> In the drawing above you could put the OL contact between L1 and the stop button. It would work and it would be documented.


 Looking for the reason behind it, the factory wiring diagrams I see they are wired like that. Can you honestly say it dose not matter?


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## Jlarson

John Valdes said:


> Who cares how its done. As long as the control circuit author draws it as it is, whats the big deal?


Exactly. There is no big deal. 



Wireman191 said:


> the factory wiring diagrams I see they are wired like that.


So.


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## Wireman191

Jlarson said:


> Exactly. There is no big deal.
> 
> 
> 
> So.


 Are you sure?


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## Wireman191

Is it just and industry standard or is there a reason behind it?


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## Jlarson

It's just what most everyone has always done I guess. Some have an idea that putting the OL contact in the grounded conductor may reduce the chance of like the contact welding closed but it's just an idea. 

There's nothing that requires you to put the OL contact on the grounded conductor.

Heck if you ask most, if not all manufactures will supply starters with the OL's on the ungrounded side.


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## Wireman191

Jlarson said:


> It's just what most everyone has always done I guess. Some have an idea that putting the OL contact in the grounded conductor may reduce the chance of like the contact welding closed but it's just an idea.
> 
> There's nothing that requires you to put the OL contact on the grounded conductor.
> 
> Heck if you ask most, if not all manufactures will supply starters with the OL's on the ungrounded side.


 Thats a better answer then so..... lol


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## nitro71

erics37 said:


> The wire going through the OL relay's N.C. contact is from the load side of the starter coil, through the contact, and back to L2. It's the wire from the load side of the load, so once the coil is energized and the control voltage is dropped across it, the conductor from there through the OLs wouldn't be the ungrounded anymore unless it was open.
> 
> (I didn't draw this, I just googled it):


Err, alrighty.


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## Butt Splice

read your specs. Nowadays they want OL's wired upstream of the coil.


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## nitro71

Butt Splice said:


> read your specs. Nowadays they want OL's wired upstream of the coil.


It really doesn't matter though. And what specs are these?


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## John Valdes

Wireman191 said:


> Looking for the reason behind it, the factory wiring diagrams I see they are wired like that. Can you honestly say it dose not matter?


Yes, I honestly can say "it does not matter".



nitro71 said:


> It really doesn't matter though. And what specs are these?


Just because you are used to seeing that drawing does not mean you have to wire it that way. 
Take that same drawing and add a jog button. I can think of several ways to draw it. All of the ways will work. So does that make them wrong? No. As long as I document the way I designed the circuit.
Wait until you have to figure out a European schematic. They do all kinds of crazy stuff. But it still works.


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## piperunner

Big John said:


> I don't know why folks do that, but I think most guys keep doing it because it's just common practice. Why does everyone flex into transformers? There's really no good reason, it's just always been done that way.
> 
> Every once in a blue moon I'll see hot switched by the OL; I've been tempted to start wiring them like that myself.
> 
> -John


Well they flex into a transformer because it vibrates . 

Now i know what your going to say its not in the code so its correct .


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## lefleuron

I am with John on this, you guys are looking too far into it. The O.L. contacts are the same as any other set of contacts. They can be wired anywhere in the circuit and still do the job.

Didn't Sq D Nema starters used to come with A2 pre-wired to the O.L.? I seam to remember the wire was threaded around the backside and already terminated.

Maybe this is the reason most people draw it up this way, and it is still usually wired this way.


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## John Valdes

lefleuron said:


> I am with John on this, you guys are looking too far into it. The O.L. contacts are the same as any other set of contacts. They can be wired anywhere in the circuit and still do the job.
> 
> Didn't Sq D Nema starters used to come with A2 pre-wired to the O.L.? I seam to remember the wire was threaded around the backside and already terminated.
> 
> Maybe this is the reason most people draw it up this way, and it is still usually wired this way.


Great Point. :thumbsup: I think they still come wired that way? Not sure though.


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## RIVETER

IBEW191 said:


> Why is the neutral the one we cut out in and overload situation? ie normally closed contacts go to A2 on the contactor coil.


It is really just the industry accepted way of doing it. It could be placed in series with the starter coil anywhere in the diagram but it seems to work there. To me, it is a good way of doing it.


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## Big John

piperunner said:


> Well they flex into a transformer because it vibrates....


 I know that's the conventional wisdom, I just don't know how sensible it actually is.

A little 60-cycle hum ain't likely to start loosening conduit in my lifetime.

-John


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## RIVETER

Big John said:


> I know that's the conventional wisdom, I just don't know how sensible it actually is.
> 
> A little 60-cycle hum ain't likely to start loosening conduit in my lifetime.
> 
> -John


You won't live forever, why risk a locknut coming loose after you're gone?


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## Big John

RIVETER said:


> You won't live forever, why risk a locknut coming loose after you're gone?












That's a 10 megawatt generator. It vibrates so much you can feel it in your shoes when you're standing in the parking lot. If that thing hasn't worked loose, it just makes me question the need on a little 25kVA transformer.

-John


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## RIVETER

Big John said:


> That's a 10 megawatt generator. It vibrates so much you can feel it in your shoes when you're standing in the parking lot. If that thing hasn't worked loose, it just makes me question the need on a little 25kVA transformer.
> 
> -John


That is a great picture but you would never know if a locknut has come loose to the point that continuity is compromised until you needed it.


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## Jlarson

Big John said:


> I know that's the conventional wisdom, I just don't know how sensible it actually is.
> 
> A little 60-cycle hum ain't likely to start loosening conduit in my lifetime.
> 
> -John


Whenever possible on new stuff I try to pipe floor mounted xformers in underground. Clean and PVC is cheap, never seen nor worried about a the locknut vibrating loose.


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## Circuit Slayer

nitro71 said:


> It really doesn't matter though. And what specs are these?


Ahem, Division 26 specs???????


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## Circuit Slayer

lefleuron said:


> Didn't Sq D Nema starters used to come with A2 pre-wired to the O.L.? I seam to remember the wire was threaded around the backside and already terminated.


Yes, and A1 was over to the aux contact for holding. I wired four different makes of starters this last week. The best was the Cerus Building Automation Starter. You could bring cl3p cable into the bottom, no need for that pesky TFFN.


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## piperunner

Big John said:


> I know that's the conventional wisdom, I just don't know how sensible it actually is.
> 
> A little 60-cycle hum ain't likely to start loosening conduit in my lifetime.
> 
> -John





John after work today iam going to show you what our engineer makes us do on the job were doing now ,

This is what they show to be done your not going to believe this over kill.


I will post a page & detail of our prints on a transformer install per engineer you will laugh but this is what they spec to just mount a transformer.

First its not what normal people do and its well wait till i get off work today .

You dont want to miss this one !


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## CheapCharlie

piperunner said:


> John after work today iam going to show you what our engineer makes us do on the job were doing now ,
> 
> This is what they show to be done your not going to believe this over kill.
> 
> 
> I will post a page & detail of our prints on a transformer install per engineer you will laugh but this is what they spec to just mount a transformer.
> 
> First its not what normal people do and its well wait till i get off work today .
> 
> You dont want to miss this one !


I can hardly wait! lol


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## Jefro

Big John said:


> That's a 10 megawatt generator. It vibrates so much you can feel it in your shoes when you're standing in the parking lot. If that thing hasn't worked loose, it just makes me question the need on a little 25kVA transformer.
> 
> -John


Awesome. What is that, hydro?


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## JRaef

The real answer to the original question is.... drum roll... because it was done that way for a long time. Sad as it may sound, we are creatures of habit. But there is a back story. I happen to know it because I had to reasearch this for a class a looooong time ago.

This practice originated out of the early days of the Automotive Industry, one of the first major adopters of electrification once Henry Ford clued us into the benefits of a flexible non-stop assembly line. Once car models began changing every year, the automakers had to start having very flexible electrical (and mechanical) systems too, because they had a system of rotation on machinery. When the 1932 model is being produced, they are rebuilding the 1929 model production line for 1933, etc. etc. That meant fast changes and it became clear that they needed standards to avoid confusion. So the automotives and trade unions formed what was eventually called the Joint Industries Council, or JIC, in around 1920 to establish standards that were easy to understand from one plant to the next. That way if they moved, the electricians (in our case) knew what they would find when they got there. JIC wiring standards prevailed well into the 1980s, when they were adopted by ANSI and NEMA.

In the old JIC standards, the predominant form of control was full voltage, and as others have mentioned, you tapped off of A phase for one side of the control circuit, then B phase for the other. So in that scheme, having the OL aux contact on the B side was actually not a bad idea because if either side went to gpound, the entire circuit stopped working to let you know. It was only much later, like after WWII, that people started using 120V controls on a regular basis. This was probably because that's what the Navy did on ships (for other reasons), and a lot of Navy electricians had never had union traning in the "old ways" of the JIC. So eventually the use of the aux. contact on the "grounded" side of the coil just happened, there really wasn't anyone making a concious effert to do it or to stop it. In reality it actually is slightly less safe that way because IF the little short wire from the A2 side of the coil and that aux. contact went to ground, the contact could open up and the coil would not drop out. That is why in most NEMA motor starters, that wire is very very short, and factory installed so as to be very unlikely to find a ground anywhere.

When I worked for a German company for a while, they thought I was NUTS for showing it that way on wiring diagrams and they is]nsisted I learn "their way" by showing it on the same side of the ladder diagram as all of the other control elements. We just placed it as the very last set of contacts before A1 on the coils, that way it was still a short wire. The problem was, all of the US based electricians using the equipment I was designing were used to looking for the OL aux contact on the "neutral" side and complained. I did in fact get a number of Consulting Engineers insist that I change it, "to match JIC standards", even though the JIC has been long gone.

Bottom line, it really doesn't matter, but it's still done that way because a LOT of electricians are still taught that way. Chaos is worse.


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## oliquir

it was very usefull wiring the o/l on neutral when using multiple motors on a machine, if any of the o/l was tripping then every motor stop. if it was wired on hot side it would have require a lot of relays to do the same job


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## Wireman191

oliquir said:


> it was very usefull wiring the o/l on neutral when using multiple motors on a machine, if any of the o/l was tripping then every motor stop. if it was wired on hot side it would have require a lot of relays to do the same job


 I wondered about that.


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## Wireman191

JRaef said:


> The real answer to the original question is.... drum roll... because it was done that way for a long time. Sad as it may sound, we are creatures of habit. But there is a back story. I happen to know it because I had to reasearch this for a class a looooong time ago.
> 
> This practice originated out of the early days of the Automotive Industry, one of the first major adopters of electrification once Henry Ford clued us into the benefits of a flexible non-stop assembly line. Once car models began changing every year, the automakers had to start having very flexible electrical (and mechanical) systems too, because they had a system of rotation on machinery. When the 1932 model is being produced, they are rebuilding the 1929 model production line for 1933, etc. etc. That meant fast changes and it became clear that they needed standards to avoid confusion. So the automotives and trade unions formed what was eventually called the Joint Industries Council, or JIC, in around 1920 to establish standards that were easy to understand from one plant to the next. That way if they moved, the electricians (in our case) knew what they would find when they got there. JIC wiring standards prevailed well into the 1980s, when they were adopted by ANSI and NEMA.
> 
> In the old JIC standards, the predominant form of control was full voltage, and as others have mentioned, you tapped off of A phase for one side of the control circuit, then B phase for the other. So in that scheme, having the OL aux contact on the B side was actually not a bad idea because if either side went to gpound, the entire circuit stopped working to let you know. It was only much later, like after WWII, that people started using 120V controls on a regular basis. This was probably because that's what the Navy did on ships (for other reasons), and a lot of Navy electricians had never had union traning in the "old ways" of the JIC. So eventually the use of the aux. contact on the "grounded" side of the coil just happened, there really wasn't anyone making a concious effert to do it or to stop it. In reality it actually is slightly less safe that way because IF the little short wire from the A2 side of the coil and that aux. contact went to ground, the contact could open up and the coil would not drop out. That is why in most NEMA motor starters, that wire is very very short, and factory installed so as to be very unlikely to find a ground anywhere.
> 
> When I worked for a German company for a while, they thought I was NUTS for showing it that way on wiring diagrams and they is]nsisted I learn "their way" by showing it on the same side of the ladder diagram as all of the other control elements. We just placed it as the very last set of contacts before A1 on the coils, that way it was still a short wire. The problem was, all of the US based electricians using the equipment I was designing were used to looking for the OL aux contact on the "neutral" side and complained. I did in fact get a number of Consulting Engineers insist that I change it, "to match JIC standards", even though the JIC has been long gone.
> 
> Bottom line, it really doesn't matter, but it's still done that way because a LOT of electricians are still taught that way. Chaos is worse.


 By far the best answer! Thankyou!:thumbup:


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## don_resqcapt19

oliquir said:


> it was very usefull wiring the o/l on neutral when using multiple motors on a machine, if any of the o/l was tripping then every motor stop. if it was wired on hot side it would have require a lot of relays to do the same job


You have to have the starters in the same enclosure to do that. 430.74


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## hub

Jlarson said:


> Exactly. There is no big deal.
> 
> 
> 
> So.


Trouble shooting is easier if there is a standard way on a 123v conrtol system. Ground and shorts are easier the find. 440v control can be real trouble if the control system is wired on an idea instead on standard way.


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## John Valdes

oliquir said:


> it was very usefull wiring the o/l on neutral when using multiple motors on a machine, if any of the o/l was tripping then every motor stop. if it was wired on hot side it would have require a lot of relays to do the same job


What? :blink: Having the OLR shut down multiple motors has nothing to do with the neutral. Its all about how you designed the control circuit. I can easily pass through all the OLR's contacts with a hot just the same as a neutral. Besides I have machines that need certain motors to run when one trips out. Circuit design determines how the machine reacts. Not all machines, motors and processes are that elementary.



don_resqcapt19 said:


> You have to have the starters in the same enclosure to do that. 430.74


No you don't. You can kill every motor in your facility with one OLR if you want too. You just have to know how.


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## Jlarson

hub said:


> Trouble shooting is easier if there is a standard way on a 123v conrtol system.


What's so hard about T-shooting OL contacts that are on ungrounded side of things? 



John Valdes said:


> No you don't. You can kill every motor in your facility with one OLR if you want too. You just have to know how.


Nothing says that you can't kill every motor. You just need to make sure you meet all the relevant codes.


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## don_resqcapt19

John Valdes said:


> ...No you don't. You can kill every motor in your facility with one OLR if you want too. You just have to know how.


 You cannot bring the switched grounded control circuit conductor out of the enclosure it originates in. Sure there are other methods to kill everything with one overload relay, but not by having the conductor between the overload relay and the coil leave the enclosure (assuming the overload relay is in the grounded conductor).


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## John Valdes

don_resqcapt19 said:


> You cannot bring the switched grounded control circuit conductor out of the enclosure it originates in. Sure there are other methods to kill everything with one overload relay, but not by having the conductor between the overload relay and the coil leave the enclosure (assuming the overload relay is in the grounded conductor).


Proving the point. When you cannot do it one way, do it another way. :thumbsup:


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## don_resqcapt19

John Valdes said:


> Proving the point. When you cannot do it one way, do it another way. :thumbsup:


The post that I originally commented on seemed to indicate that the poster was using the switched grounded conductor directly to trip out other staters and my comment said that the switched grounded conductor can not leave its enclosure.

That being said, there must be a number of people who do this. I recently installed 13 back to back sections of CH MCC and everyone of the starters had the "switched grounded conductor" from the overload relay brought out to the field terminal block in the MCC bucket.


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## hub

Jlarson said:


> What's so hard about T-shooting OL contacts that are on ungrounded side of things?
> 
> 
> 
> Nothing says that you can't kill every motor. You just need to make sure you meet all the relevant codes.


Ol contacts are placed in netural side so contacts can not be shorted around, thus keeping the coil from dropping out. If there is a short around the OL it would be line to line, blowing the fuse on the control.


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## John Valdes

don_resqcapt19 said:


> The post that I originally commented on seemed to indicate that the poster was using the switched grounded conductor directly to trip out other staters and my comment said that the switched grounded conductor can not leave its enclosure.
> 
> That being said, there must be a number of people who do this. I recently installed 13 back to back sections of CH MCC and everyone of the starters had the "switched grounded conductor" from the overload relay brought out to the field terminal block in the MCC bucket.


That was the spec. When I design a control system I am the owner and the author of the system and the drawings in theory.
I could have easily designed your system to use the ungrounded conductor to facilitate OLR shutdown.
The sky is the limit and just because it's been done that way before, does not mean you or I have to do it that way. If its in the spec and you are just making connections, then of course follow the spec. 
But when you are asked to design and implement a control system you have the ability to leave old ways of thinking and old wives tales to the wayside. 
I like to call it being creative. 
Lets make one thing clear. I draw prints and admonish those who do not and leave the next guy in the dark. Creative control schemes are fun and make work interesting. Making them easy to understand for next guy is why a good drawing is always important. Always!


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## don_resqcapt19

John,
You are missing my point. That point is that if you switch the grounded conductor to provide the motor overload shut down, than that switched conductor is not permitted to leave its enclosure.


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## Jlarson

hub said:


> Ol contacts are placed in netural


They're placed there because some people are hell bent on sticking to old ways.


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## Frank Mc

Hi Guys

Most Oz sparks get freaked when the see the o/l connected to the neutral leg...For me it was normal...probably cause i served my time for an American company.....Just wired some panels and we still connect the o/l n/c contact in the control circuit and put the n/o contact into the plc...

Frank


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## John Valdes

don_resqcapt19 said:


> John,
> You are missing my point. That point is that if you switch the grounded conductor to provide the motor overload shut down, than that switched conductor is not permitted to leave its enclosure.


Don, I do understand. I just am being realistic. In a manufacturing environment, the NEC is rarely considered when designing the control system. Functionality rules in this environment.
I know it's not right and may not be code, but at the end of the day the machines will run. NEC or not.
Just being brutally honest.


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## fjl810

I would just like to share this about ol relays on some cranes.
Four ol's in series, trolley low speed, trolley high speed, hoist low speed and hoist hi speed wired to open the UP control circuit of the crane.

The trolley motor ckt. does not drop out when trolley motor is overloaded.

I understand the reason , You can lower the load.
Not so good for the trolley motor, or the hoist motor.:001_huh:


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## don_resqcapt19

John Valdes said:


> ...
> I know it's not right and may not be code, but at the end of the day the machines will run. NEC or not.


Yes, they will run just fine, but they might not stop on an overload.


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## John Valdes

don_resqcapt19 said:


> Yes, they will run just fine, but they might not stop on an overload.


Now. I do not understand what you are talking about. Did I miss something? What do you mean by "they might not stop"?
Connected correctly all motors will stop that you want to stop.


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## oldtimer

John Valdes said:


> Now. I do not understand what you are talking about. Did I miss something? What do you mean by "they might not stop"?
> Connected correctly all motors will stop that you want to stop.




I think he means the overload relay may not trip! :blink:


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## John Valdes

oldtimer said:


> I think he means the overload relay may not trip! :blink:


I must have missed something Al. As I have no idea what he means.


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## don_resqcapt19

John Valdes said:


> Now. I do not understand what you are talking about. Did I miss something? What do you mean by "they might not stop"?
> Connected correctly all motors will stop that you want to stop.


 The reason the code rule says you can't have the switched grounded conductor of the control circuit leave the starter enclosure is because a ground fault on this conductor will prevent the overload relay from stopping motors if it sees an overload. A ground fault on a grounded conductor will never be noticed as it does not impair the normal function of the ciruit...just the overload trip function.


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## JRaef

don_resqcapt19 said:


> The reason the code rule says you can't have the switched grounded conductor of the control circuit leave the starter enclosure is because a ground fault on this conductor will prevent the overload relay from stopping motors if it sees an overload. A ground fault on a grounded conductor will never be noticed as it does not impair the normal function of the ciruit...just the overload trip function.


If I may...

This entire tangent seems to be predicated on one comment about a seldom used idea of having one OL relay shut down a group of motors. That in and of itself is rare, and doing it by running a grounded neutral side of multiple coils would be more rare still. On top of that, it is only illegal IF the neutrals exit the enclosures. 

So here is the problem scenario Don has described as I see it. 5 starters, each in their own separate enclosures. Starter A is a machine of some sort, starters B, C, D and E are something like feeder conveyors for the machine on starter A. So if starter A trips on OL, you want all of the others to turn off at the same time. Theoretically the cheapest way to do that would be to take the neutral off of the down stream side of the OLR aux. contact in B, C, D and E and instead of connecting to the Neutral inside of each starter enclosure, tie them together and run them back to Starter A and connect that common wire in series with the OLR aux. contact for starter A. That way if starter A trips, they all trip. Also you could put them all in series with each other, so if any one trips they all trip as well. *The problem with those scenarios is that since they are all in separate enclosures, you will have a gounded neutral run outside of the boxes, a violation of the NEC.* If one of those wires goes to ground, the circuit remains complete and when the OLR contact opens, there is no difference and the starter remains engaged.

If however all of the starters are in the same box, you could legally do this. I don't like it and there are a dozen or more other ways to accomplish the same thing that would be more immediately clear to a future troubleshooter, but this could technically work.

But seriously, even in the same enclosure this is a rare set of circumstrances and probably not germaine to the original question, nor is it worth all the bandwidth we have devoted to it in my opinion. 

A sketch would do wonders here, I'll scan one if I have the time.


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## John Valdes

don_resqcapt19 said:


> The reason the code rule says you can't have the switched grounded conductor of the control circuit leave the starter enclosure is because a ground fault on this conductor will prevent the overload relay from stopping motors if it sees an overload. A ground fault on a grounded conductor will never be noticed as it does not impair the normal function of the ciruit...just the overload trip function.


I see your point now. However, in multiple motor schemes it is highly unlikely the grounded conductor will be used for any switching. At least it would never happen on a system I designed.
But I do get it now. Thanks Don.


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## don_resqcapt19

John Valdes said:


> I see your point now. However, in multiple motor schemes it is highly unlikely the grounded conductor will be used for any switching. At least it would never happen on a system I designed.
> But I do get it now. Thanks Don.


 John,
This whole thread was about the overload relay contact being used on the grounded side of the control circuit in most motor starters. I just assumed that your comments were about the same type of installation. The only code issue is the case where that switched grounded conductor leaves its original enclosure.


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## mrmike

John Valdes said:


> What? :blink: Having the OLR shut down multiple motors has nothing to do with the neutral. Its all about how you designed the control circuit. I can easily pass through all the OLR's contacts with a hot just the same as a neutral. Besides I have machines that need certain motors to run when one trips out. Circuit design determines how the machine reacts. Not all machines, motors and processes are that elementary.
> 
> 
> 
> No you don't. You can kill every motor in your facility with one OLR if you want too. You just have to know how.


 
In essence, one Motor Starter O/L can shut down multiple motors, , but usually not thru that conductor that goes to neutral from the O/L of that circuit.. 
It has been my experience that when that motor starter O/L trips, an Auxillary Contact on that starter drops out another motor starter wired in its control circuit. That starter might also have an Aux contact that drops out another- & so on, like a Dominoe effect dropping out other motors........... .


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## shadone

There are certain conditions where an induced voltage could cause a coil to energize. I have seen this happen and a piece of equipment could start. I will continue to use the neutral just for that reason when wiring overload contacts.


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## Wirenuting

It’s located there to prevent the coil from pulling in due to a fault. 
I’ll dig around for the diagram that shows it. It might be in an uglys book.


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## glen1971

Seven year old thread?! How would one go about googling and deciding to awake a near dead thread?


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## MechanicalDVR

shadone said:


> There are certain conditions where an induced voltage could cause a coil to energize. I have seen this happen and a piece of equipment could start. I will continue to use the neutral just for that reason when wiring overload contacts.


Welcome aboard @shadone!

Enjoy your ride here.


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## Wirenuting

glen1971 said:


> Seven year old thread?! How would one go about googling and deciding to awake a near dead thread?


Shoot, I missed the date :vs_mad:


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## Flyingsod

glen1971 said:


> Seven year old thread?! How would one go about googling and deciding to awake a near dead thread?




Try googling anything. You get tons of years old threads. If you don’t purposefully look at dates it’s easy to reply. And really who cares. If there’s something new to add it might be better than making a new thread and just rehashing everything already said. 

What’s really annoying is when someone doesn’t bother reading what’s already been posted in the thread. 

Sent from my iPhone using Tapatalk


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## John Valdes

Welcome to Electrician Talk shadone.
Thanks for taking the time to fill out your profile.


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## lmicky

whether you open contactor coil circuit in series with A2 or A1 its the same.during an overload situation it will in either case open contactor power contacts to disconnect load,but the common practice is to connect in series with A1 contactor coil connection,


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## SutherLAN

Love me some timeless threads... Listen wanted to make some input that actually DIFFERS than everyone's repeated rhetoric. I read a code from my book (CEC - the canadian NEC): *14-404 Control devices ahead of overcurrent devices*
Control devices used in combination with overcurrent devices or overload devices for the control of circuits or apparatus shall be connected so that the overcurrent or overload devices will be dead when the control device is in the open position, except where this is impracticable.


This way if the overload trips, both sides of overload contact are dead no matter what since the control device coil has lost its voltage path.



Another thought was to do with "why was it always done this way?" - i'm not doing research but i doubt they were always resettable o/l's - they were replaceable, the maintentance probably appreciated being able to test or replace something without turning it all the way off - like replacing fuses.


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## Abenr

Neutral, neither high nor low, is zero. Neutral ungrounded power supply system, in order to improve the reliability of power supply, if the speed break tripping reliability can not be guaranteed. The neutral point is ungrounded. In case of single-phase short-circuit to the ground, the ground potential is the same as the grounded phase line, and the circuit cannot be formed with the neutral point. In a three-phase three-wire circuit, if the ground is changed to zero, the voltage between the electrical shell and the ground will be changed into phase voltage, which will make the circuit not work normally, and all the people who meet the shell will be electrocuted.


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