Adjustable Trip breaker allowed for main service breaker?

[buzzbar]

I am replacing an old 200A 480V service with new gear. My supplier has given me a quote for a panel with a 250A main breaker, with adjustable trip rating. If I "dial" the trip rating down to 200A, is this acceptable? I can't find any restrictions in the NEC, but I thought I'd ask here.

Thanks guys.

Andy

 

[rlundsrud]

Why wouldn't it be allowed?

 

[ron]

As long as it is a
"Restricted Access Adjustable-Trip Circuit Breakers."
A circuit breaker(s) that has restricted access to the adjusting means shall be permitted to have an ampere rating(s) that is equal to the adjusted current setting (long-time pickup setting). Restricted access shall be defined as located behind one of the following:
(1) Removable and sealable covers over the adjusting means
(2) Bolted equipment enclosure doors
(3) Locked doors accessible only to qualified personnel

 

[packersparky]

I am replacing an old 200A 480V service with new gear. My supplier has given me a quote for a panel with a 250A main breaker, with adjustable trip rating. If I "dial" the trip rating down to 200A, is this acceptable? I can't find any restrictions in the NEC, but I thought I'd ask here.

Thanks guys.

Andy

Yes, if the breaker complies with 240.6(C).

Ron beat me to it.

 

[buzzbar]

As long as it is a
"Restricted Access Adjustable-Trip Circuit Breakers."
A circuit breaker(s) that has restricted access to the adjusting means shall be permitted to have an ampere rating(s) that is equal to the adjusted current setting (long-time pickup setting). Restricted access shall be defined as located behind one of the following:
(1) Removable and sealable covers over the adjusting means
(2) Bolted equipment enclosure doors
(3) Locked doors accessible only to qualified personnel

Thanks, that answers my question.

 

[buzzbar]

Why wouldn't it be allowed?

I would think that it would be just fine, but along the road called life, I have found that it's better to figure it out before it's installed, and failed by an inspector. I didn't want to have a "d'oh!" moment. Thanks to this forum, I've managed to avoid many of those moments.

Thanks again guys.

Andy

 

[Jraef]

Be a little careful though. Adjustable THERMAL-MAG circuit breakers are NOT going to be UL listed as "Main or Feeder Circuit Breakers", they can ONLY be used as "Motor Protection Circuit Breakers" as a branch protective device.

The only allowable adjustable trip breakers that are UL489 listed to be used as Mains or Feeders are those with Electronic Trip Units (ETUs). The idea behind it, as explained to me by a UL guy, is because if it is an ETU, that implies it will be a "supervised" setting in an industrial or commercial facility where access is restricted. I guess the idea was that a residential user would not spring for the extra cost of an ETU because up until recently, they were only offered on 400A frames and above. That has now changed, so it will be interesting to see how this plays out over time.