120v combination motor starter control circuit conductors

[Natfuelbilll]

Job is calling for 120V CMS single phase.

My gut says I can use the motor circuit conductors L and N for the control circuit conductors. With a 1amp fuse on the L.

Then reading the code I see the control circuit needs to be grounded and needs to open all control circuit conductors. That means I would need to also fuse the N.

Maybe I need a 24V control power transformer instead of a 120V CPT.

Hmmm

 

[ptonsparky]

Where do you read that the control circuit must be grounded?
What is CMS?

 

[david luchini]

Where do you read "needs to open all control circuit conductors"?

 

[Natfuelbilll]

I thought I saw where the control circuit leaves the combination motor starter. CMS

 

[ptonsparky]

I thought I saw where the control circuit leaves the combination motor starter. CMS

See 430.72. Pay attention to the exceptions.

 

[Natfuelbilll]

Where do you read "needs to open all control circuit conductors"?

430.75 (A)

 

[david luchini]

430.75 (A)

430.75(A) doesn't say anything about opening "all control circuit conductors." If your control circuit is tapped from the load side of the CMS disconnecting means, then the control circuit will be disconnected from its source of supply when the CMS disconnect is in the open position.

 

[Jraef]

Besides, you would NEVER fuse the neutral.

 

[Ainsley Whyte]

Besides, you would NEVER fuse the neutral.

never heard of fuse neutral in all my time too

 

[ptonsparky]

430.75 (A)

NM. Already covered.

 

[Natfuelbilll]

I know these things. Some smarty pants engineer is asking for 2 primary fuses and a secondary fuse. He knows it's all a 120v single phase. I was thinking maybe a isolation transformer to meet his specs. A starter is wayyyyy overkill as the control is a thermostat. "But it's in the specs" he says.

 

[Eddie702]

The engineer is thinking about a transformer

 

[Natfuelbilll]

Okay to use the motor circuit conductors L and N, fuse the L and pass the L out of CMS enclosure to a thermostat and return to the control circuit?

 

[Besoeker3]

Job is calling for 120V CMS single phase.

My gut says I can use the motor circuit conductors L and N for the control circuit conductors. With a 1amp fuse on the L.

Then reading the code I see the control circuit needs to be grounded and needs to open all control circuit conductors. That means I would need to also fuse the N.

Maybe I need a 24V control power transformer instead of a 120V CPT.

Hmmm

I would never fuse the neutral.

 

[retirede]

Okay to use the motor circuit conductors L and N, fuse the L and pass the L out of CMS enclosure to a thermostat and return to the control circuit?

Yes...