overloads run on line two side.

[Barndog]

Why in motor controls do they run the overloads through the neutral (L2) side but all other switches are on the L1 side??

 

[stew]

L1 is where you typically land the black or hot conductor on a 120 volt starter. L2 is the neutral. You want the hot as the front end of your control circuit and not the neutral.

 

[kwired]

L1 is where you typically land the black or hot conductor on a 120 volt starter. L2 is the neutral. You want the hot as the front end of your control circuit and not the neutral.

And the overload contact is not a control device?

NEMA starters are about the only place you see this. Any other device usually has all control devices ahead of the load on the ungrounded conductor if it is 120 volt control voltage. Other voltages may have controls in either side or even both sides.

 

[don_resqcapt19]

The most common is for the overload relay to be in the L2 side, but there are some engineers that specify it to be in the L1 side like the other controls. If it is in the grounded conductor the wire between the overload relay contact and the stater coil is not permitted to leave the starter enclosure. 430.74

 

[Barndog]

Is there any historical reason for this or was it a design issue. Just something i wondered about so i thought i would ask the question.

 

[jim dungar]

It is much easier to wire a multi-coil assembly (i.e. reversing starter) if the OL relay contact is on the L2 side.

 

[Barndog]

It is much easier to wire a multi-coil assembly (i.e. reversing starter) if the OL relay contact is on the L2 side.

you could run L2 through the overload relay then pigtail to both coils but you could also do with L1 if you put the OL first then parallel the other contacts to the two contactors.

 

[jim dungar]

you could run L2 through the overload relay then pigtail to both coils but you could also do with L1 if you put the OL first then parallel the other contacts to the two contactors.

Both of which present the possibility of field wiring affecting the relatively 'unrobust' overload contact (which normally has poor short circuit withstand ability), whereas its factory location renders it relatively safe from wiring misuse/abuse.

I am not saying "L2" is the best location, I am simply providing historical reason why NEMA and JIC standards have allowed it to exist where it does.

 

[Barndog]

Both of which present the possibility of field wiring affecting the relatively 'unrobust' overload contact (which normally has poor short circuit withstand ability), whereas its factory location renders it relatively safe from wiring misuse/abuse.

I am not saying "L2" is the best location, I am simply providing historical reason why NEMA and JIC standards have allowed it to exist where it does.

Ok. thank you. thats what i was looking for.