Main Circuit Breaker Supply

[Kobe85]

I have a vendor who typically uses 1200A circuit breakers and adjusts them for each individual panel. i.e. They will adjust the 1200A down to 900A for the application and supply the panel.

My question is, can I supply the wiring based on the 900A breaker setting, or do I need to feed it with wires based on the 1200A max rating of the circuit breaker?

Thanks,!

 

[jumper]

I am pretty sure it is max rating, because someone could always dial up the breaker at a later date, unless you have restricted access.

Look at 240.6(B) and (C).

 

[kingpb]

I am pretty sure it is max rating, because someone could always dial up the breaker at a later date, unless you have restricted access.

Look at 240.6(B) and (C).

Supply cable based on setting.

It would be extremely unlikely that you are going to have an adjustable breaker installed in a setting that you wouldn't meet one of the 3 choices in 240.6(C).

If it makes you feel better, put a label on the breaker that says cable is based on ???? or whatever setting you choose; i.e. 900A in this case.

 

[templdl]

I have a vendor who typically uses 1200A circuit breakers and adjusts them for each individual panel. i.e. They will adjust the 1200A down to 900A for the application and supply the panel.

My question is, can I supply the wiring based on the 900A breaker setting, or do I need to feed it with wires based on the 1200A max rating of the circuit breaker?

Thanks,!

Non interchangeable trip units? What prevents the end user from changing the breaker rating?

 

[augie47]

240.6(C) covers this.

(C) 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

 

[jim dungar]

What prevents the end user from changing the breaker rating?

The same thing that prevents them from using 1200A fuses instead of 900A ones.