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anelson

Wire Color Requirements

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If you have the neutral of a relay coil wired to a normally closed contact and then to the system neutral, what color should the wire between the relay coil and contact be? I was always under the impression to use white since in my head it was  grounded AC, but as it was being discussed today some thought it should be red since if the contact is open then it is not grounded AC anymore. Anyone advice on this is appreciated.

Thanks,

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I'm not sure what's legally required, but in our machines, the white wire starts at the coil, even if the NC contact of the O/L relay is in series. We have some machines where the coil "neutrals" are all jumpered together and then pass through all of the overload relay contacts in series before being connected to system neutral. This means that if any overload relay trips, all of the contactors will drop out. All of the wiring is white, so it's very messy to trace the wiring.

Personally, I might lean towards using a different color if there's a contact in between. I don't think I've ever seen it done that way, though.

 

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White because the

potential has been consumed.

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Posted (edited)

11 hours ago, NevergoldMel said:

White because the

potential has been consumed.

...except when the O/L is tripped. Then we have a white wire with line voltage on it.

I've always wondered why we put the O/L contact on the neutral side of the coil. Why not put it on the high side of the coil?

ETA:

I guess to do what I described above, where a lot of contactors are dropped when any one is tripped... I've always seen it in the neutral side of the coil, even when it's a standalone starter, though.

Edited by Joe E.

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I've seen alot of electricians wire the OL contact before the coil rather than after. I'm not sure what US code requires vs Canadian CSA though. 

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all switching need to be done on the live side. some overload relays have special construction so even though contact is on the neutral side, only one wire is exposed - one that goes to neutral and it is white. the "live" end of the contact when it is open is not accessible, it is internally connected to A2 of the relay or contactor. this is what allows such use, otherwise - OL contact need to be wired on the live side, before coil and then both sides of OL are red wires. 

 

what code requires can be seen in the code book. no electrician should be without one. 

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Hmmm. 

 

I decided to double check since I remembered something about this years ago from school. In the CSA 14-016 it does say that "Devices required by this Section shall not be connected in any grounded conductors except where..." (not relevant a and b sub-rules)   However motor overloads are not required by Section 14. They are required by Section 28. In that section only 28-506 seems to apply. In that if the overload is wired on the load side of the coil if the wire becomes accidently grounded between the coil and the overload the overload would no longer prevent the motor from starting or stop it. Here is the text.

28-506 - When Power for a control circuit for a motor controller is obtained conductively from a grounded system, the control circuit shall be arranged so that an accidental ground in the wiring from the controller to any remote or signal device will not

a) start the motor; or

b) prevent the stopping of the motor  by the normal operation of any control or safety device in the control circuit

 

So my read on that is if you're using an floating/ungrounded dc system or a system where both wires are live like in 208v  this rule would not prevent you from wiring in your overload on the load (A2) side of the coil. 

 

28-200 to 28-206 are about branch and feeder conductor over current protection so the rule in 14-016 would not apply. 

 

Let me know if I'm missing a relevant rule. 

 

 

Edited by Morberis

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