Amperage "cushion"

[HoosierSparky]

When derating a main breaker (200 to 175) to accommodate adding a 60 solar feed to a residential service, the load calcs come out at 173.9A. The numbers work. Barely. Is there a "buried" section of the code that requires a "cushion" for adding loads later other than "good practice"?

 

[gadfly56]

When derating a main breaker (200 to 175) to accommodate adding a 60 solar feed to a residential service, the load calcs come out at 173.9A. The numbers work. Barely. Is there a "buried" section of the code that requires a "cushion" for adding loads later other than "good practice"?

I have never heard of a cushion being required. Local laws may say different. That said, the residential load calcs in the NEC are very, very conservative. I doubt you'd need a cushion of any sort.

 

[HoosierSparky]

I have never heard of a cushion being required. Local laws may say different. That said, the residential load calcs in the NEC are very, very conservative. I doubt you'd need a cushion of any sort.

Thanks. I tend to be VERY conservative when loading panels. Since the advent of LED's, loads have come down, a lot, but being in the trade since '75, I like to leave options for adding later. Cheaper to have space now, than add it later.

 

[electrofelon]

Thanks. I tend to be VERY conservative when loading panels. Since the advent of LED's, loads have come down, a lot, but being in the trade since '75, I like to leave options for adding later. Cheaper to have space now, than add it later.

I wouldn't worry about it. 99.9% of homes will never even use HALF of 175A

 

[HoosierSparky]

I understand that most homes will never see 175A. Most of the homes, here, that are getting solar are in the 3-7,000 sq ft range.

 

[gadfly56]

I understand that most homes will never see 175A. Most of the homes, here, that are getting solar are in the 3-7,000 sq ft range.

Dang, I for sure made a bad career choice. I remember 30 years ago when I was looking for my first home seeing entire neighborhoods (new subdivisions) starting at $325,000 and they weren't nearly that big. Where do I sell my soul?