Derating Residential NM-B Homeruns

[C. M. Joy Company]

Custom house 8800’ sq. ft. with ALL panels centrally located in basement mechanical area. NO SUB PANELS on either living level. My question is has anyone installed 12/2 to the first device of a 15A branch circuit and then installed 14/2 for all additional wiring between devices? Basically, derating to the first device instead of installing a can or trough above or remotely from the panel to use for derating purposes. It’s a distance concern as opposed to # of CCCs. Thoughts? Thanks everyone!

 

[HEYDOG]

There is nothing in the code against doing that. My only concern would be at some point someone might see the #12 at the panel and change the 15 amp breaker out to a 20 amp breaker. You might be better off installing sub panels so that you have shorter runs!

 

[augie47]

Fairly common approach here when addressing voltage drop.
I have seen electricians mark those circuits in the panel to discourage random breaker size increases.

 

[infinity]

Not an issue starting with #12 and transitioning to #14 as long as you have a 15 amp OCPD.

 

[C. M. Joy Company]

There is nothing in the code against doing that. My only concern would be at some point someone might see the #12 at the panel and change the 15 amp breaker out to a 20 amp breaker. You might be better off installing sub panels so that you have shorter runs!

Sub panels are an absolute NO per homeowner, architect and designer unfortunately. As far as someone else coming in down the road, this particular client ONLY uses the same contractors, so there is no chance I won’t be the one working on this property in the future. I appreciate your input.

 

[C. M. Joy Company]

Fairly common approach here when addressing voltage drop.
I have seen electricians mark those circuits in the panel to discourage random breaker size increases.

I’m the only EC that’ll ever be working in this house so that isn’t an issue. But I do love your idea of making notations AT the panel just in case. Thank you!

 

[infinity]

I wouldn't be concerned about someone changing the breaker in the future. #14 conductors are really rated for 20 amps anyway. Besides no one should be randomly changing circuit breakers.

 

[rc/retired]

Custom house 8800’ sq. ft. with ALL panels centrally located in basement mechanical area. NO SUB PANELS Thoughts? Thanks everyone!

If there is a main disconnect outside, then the panels in the basement ARE subpanels.
What code cycle are you using? What is the problem with a subpanel?
That aside, I wired a 15000 sq. ft home with 0 problems of voltage drop.

Ron

 

[Frank DuVal]

I’m the only EC that’ll ever be working in this house so that isn’t an issue.

I hope you are 20 and the house will be torn down in 50 years or less!

I work in houses where the prior electrician did the work in the 20s. Not 2020, 1920. So does Larry.

 

[Frank DuVal]

What is the problem with a subpanel?

Wait, I can answer that, architect thinks they are UGLY!

 

[infinity]

Sub panels are an absolute NO per homeowner, architect and designer unfortunately

Just give them what they want and charge accordingly. Given the size of the house no subs sounds like an absolutely terrible design but if that's what they want they can pay the additional cost of NOT installing them.

 

[Sberry]

Typical, huge home with crap utilities.

 

[drcampbell]

... I work in houses where the prior electrician did the work in the 20s. Not 2020, 1920. So does Larry.

I was involved in a rehab of a 1905 row house in Detroit. The original service was an asbestos-lined wooden fusebox with two fuses for each three-bedroom unit.

 

[Joethemechanic]

I was involved in a rehab of a 1905 row house in Detroit. The original service was an asbestos-lined wooden fusebox with two fuses for each three-bedroom unit.

Was it still working?

 

[drcampbell]

No, it had been upgraded. Probably between 1946 and 1966 -- Cloth-covered 2-wire NM, with much of the original K&T still connected.