Sizing dwelling unit feeders

[Rpower3970]

I just watched your video labeled: “sizing dwelling unit feeder wire”

Question:
If I have 200amp service wires coming into a 200amp breaker/ panel board with feed thru lugs, it is permitted to have the dwelling unit feeder wires rated for 200 amps feeding a 150 amp sub panel with 150 amp breaker?

Note: The lugs on the breaker are rated/ listed to accept the wire size of the 200 amp wire.

 

[Dennis Alwon]

Yes you can. You can always use a wire rated for more amps than the breaker. One way to help with voltage drop is to upsize the conductor.

 

[Dennis Alwon]

You can't use the opposite. For instance, you cannot use 150 amp conductor on a 200 amp breaker.

 

[Rpower3970]

In this instance, I was updating the entrance. I put a 200 amp Service-outside meter channel/ disconnect. I ran 200 amp wire feeding the existing panel ( now making it a sub panel) which was rated for 150 amps. And planned to replace the 150 amp panel with a 200 amp rated panel in future.

The one electrical inspector told me it was not permitted and one told me it was.

 

[Rpower3970]

Is there a code reference for this?

 

[Dennis Alwon]

In this instance, I was updating the entrance. I put a 200 amp Service-outside meter channel/ disconnect. I ran 200 amp wire feeding the existing panel ( now making it a sub panel) which was rated for 150 amps. And planned to replace the 150 amp panel with a 200 amp rated panel in future.

The one electrical inspector told me it was not permitted and one told me it was.

Always ask the one who said no to give a code for the rejection. He won't be able

 

[Dennis Alwon]

There is nothing in the code that says it is non-compliant therefore it is compliant. There wouldn't be a section that requires you to upsize the equipment grounding conductor when you upsize the conductor if it weren't allowed.

 

[tortuga]

Is there a code reference for this?

408.36 covers Overcurrent Protection for panelboards, if the panel is protected by a 150A breaker your good to go.
If the panel is a main lug only then you need to protect it with a 150A breaker.

 

[LarryFine]

Is that a 3- or 4-wire feeder?

 

[Fred B]

I just watched your video labeled: “sizing dwelling unit feeder wire”

Question:
If I have 200amp service wires coming into a 200amp breaker/ panel board with feed thru lugs, it is permitted to have the dwelling unit feeder wires rated for 200 amps feeding a 150 amp sub panel with 150 amp breaker?

Note: The lugs on the breaker are rated/ listed to accept the wire size of the 200 amp wire.

This is often done due to sizing wire for voltage drop. One consideration is that what ever reason you are "upsizing" the ungrounded conductors other than the limited exclusion related to 310.15(B)(C), the grounding conductors would need to be increased proportionally to the ratio of increase in the ungrounded conductor size 250.122(B)