# Motor control wiring question.



## erics37 (May 7, 2009)

Each coil would drop 240 volts and you'd do some damage or else they wouldn't work, or both. It would be just like wiring two identical light bulbs in series on a 120 volt circuit. Each bulb would get half the voltage and be half as bright.


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## newguy55 (Dec 3, 2012)

So i would double my voltage? Since they are off a 120v circuit.


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## bill39 (Sep 4, 2009)

Before someone jumps all over you about maybe not being an electrician and giving out help to amatuers on this website.......

What you need understand is there are two distinct parts of the starter wiring:
*the power circuit (which must be matched with the motor voltage)
*the control circuit (which is USUALLY a lower voltage: 120VAC, 24VDC, etc).

The magnetic coil of the starter is pulled in by the control circuit so it must match that voltage.

Hopefully you're just an apprentice looking for answers and not doing this work yourself.

Back in the old days there was 480VAC control wiring but I think the NEC no longer permits it.


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## Wirenuting (Sep 12, 2010)

I think you need to figure out what your looking at before you fix it. 
Pick up this book.


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## EBFD6 (Aug 17, 2008)

Why would you want to wire two coils in series? There would never be a reason to do this. 

If you tell us what it is you're trying to accomplish we may be able to help you better.


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## glen1971 (Oct 10, 2012)

bill39 said:


> Back in the old days there was 480VAC control wiring but I think the NEC no longer permits it.


There are still quite a few places up here that have 480 volt control...Not real common, but a few..


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## JRaef (Mar 23, 2009)

EBFD6 said:


> Why would you want to wire two coils in series? There would never be a reason to do this.
> 
> If you tell us what it is you're trying to accomplish we may be able to help you better.


I totally aggree, there is no valid reason for ever doing this. Are you (newguy55) possibly misthinking what "wiring in series" means for coils?

Please describe EXACTLY what you have and what you are trying to do, it sounds as though maybe you are misinterpreting something, especially after the "Since they are off a 120V circuit" comment. If you were thinking that because you have 120V control power and 480V coils, you could wire the coils in serise, that is completely the wrong way to go about this and it is an accident waiting to happen. Replace the coils with 120V versions if that is the case.


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## lims640 (Dec 1, 2012)

newguy55 said:


> Im not that experienced with motor control and would like to know what would happen if you were to wire two starter coils for 480v motors in series?


it would be an expensive mistake...

please let us know what you are trying to accomplish so we can help you...

perhaps you mean that you only want the second motor to start if the first is on? in which case you could wire your control power thru the NO aux contacts on the first motor starter... i think your idea of 'in series' is different then what most of us are imagining.... please explain more...

also, make sure that you have someone with you that knows what they are doing if you are "not that experienced with motor control" nobody deserves to lose a friend/family member this close to christmas... electricity is serious stuff... watch an arc flash video if you don' believe me...


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## buddhakii (Jan 13, 2011)

Just as a side note; I would never ever try this but if you have two motors that start at the same time you could wire the 120 volt coils in series with 240 volt right? Is there actually anything in the NEC that would prohibit this?


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## ce2two (Oct 4, 2008)

He is suppose to be an industrial electrician..:no:...:whistling2:series aiding ...batterys ok,not coils:no:


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## buddhakii (Jan 13, 2011)

ce2two said:


> He is suppose to be an industrial electrician..:no:...:whistling2:series aiding ...batterys ok,not coils:no:


:blink: I realize it's not something you would really want to do you a$$, hence the qualifier. If you don't ever think outside the box how in the heck do you do maintenance?


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## running dummy (Mar 19, 2009)

It sounds like he is asking if he would be able to start two separate motors from one function. 

Two separate starters from one initiating device (sorry for my lack of terminology knowledge but, timer, start/stop etc)

I could be totally misinterpreting him though :lol:


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## EBFD6 (Aug 17, 2008)

running dummy said:


> It sounds like he is asking if he would be able to start two separate motors from one function.
> 
> Two separate starters from one initiating device (sorry for my lack of terminology knowledge but, timer, start/stop etc)
> 
> I could be totally misinterpreting him though :lol:


If that were the case he would need to wire the coils in parallel, not series.


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## running dummy (Mar 19, 2009)

Exactly. He may just have the terms mixed up.


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## glen1971 (Oct 10, 2012)

buddhakii said:


> Just as a side note; I would never ever try this but if you have two motors that start at the same time you could wire the 120 volt coils in series with 240 volt right? Is there actually anything in the NEC that would prohibit this?


The next guy that would go and try troubleshooting would be ripping his hair out trying to figure out why two coils are in series...So long as if one coil fails open there wouldn't be a voltage problem, but if one failed shorted, then you are putting 240 volts to a 120 volt coil...

Why not wire them 120 volt in parallel? Would accomplish the same thing and be done the right way...


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## nolabama (Oct 3, 2007)

Or he's a complete dumbass trying to blow up some stuff. Lol. J/k. We will never know.


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## sparky970 (Mar 19, 2008)

glen1971 said:


> There are still quite a few places up here that have 480 volt control...Not real common, but a few..


There's a lot at one of the paper mills we work at. Start/stops and indictator lights too


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## micromind (Aug 11, 2007)

glen1971 said:


> There are still quite a few places up here that have 480 volt control...Not real common, but a few..


I've seen (and done) 480 controls. Sometimes (like a start/stop in the starter enclosure) it makes a lot of sense. 

I've installed plenty of 480 pilot lights. They're the transformer kind and use 6.3 volt lamps, usually #755s. 

If 240 were applied to two 120 starter coils connected in series, it might work or maybe not. Even with both starters identical, if one of the pulled in sooner than the other, there'd be a serious voltage imbalance because of differing inrush times. The coils might be able to take it though.


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## xsryman (Dec 4, 2012)

newguy55 said:


> Im not that experienced with motor control and would like to know what would happen if you were to wire two starter coils for 480v motors in series?


basically from what everyone else has said...don't try this at home. LOL. If you have a coil that is 240 then you need to use 240. You should not try to Half *$$ engineer stuff. That's how people get hurt. Sorry to sound unhelpful but i would hate to see anyone get hurt. :thumbup:


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## wendon (Sep 27, 2010)

xsryman said:


> basically from what everyone else has said...don't try this at home. LOL. If you have a coil that is 240 then you need to use 240. You should not try to Half *$$ engineer stuff. That's how people get hurt. Sorry to sound unhelpful but i would hate to see anyone get hurt. :thumbup:


Ah, the voice of reason!:thumbup: It would be totally hack in my opinion. It is possible to do things totally Cletis but still pass the code. The code is the minimum standard.


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