800 Amp 3 phase 208 volt breaker

[Schmidty0126]

I have a 800 amp 3 pole breaker with trip ratings on breaker installed in a 4000 amp main switch board .The continuous load on the panel being fed by that breaker is 672 amps would parallel 750 Aluminum be allowed to connect to the breaker

 

[jumper]

Welcome,

Assuming 75C terminals and 75C conductors rated at 385A, then yes per 240.4(B).

If a wire type EGC is used if must be full sized per T250.122 in each raceway.

 

[electrofelon]

I have a 800 amp 3 pole breaker with trip ratings on breaker installed in a 4000 amp main switch board .The continuous load on the panel being fed by that breaker is 672 amps would parallel 750 Aluminum be allowed to connect to the breaker

First problem is if the load is indeed continuous, you dont have enough room for the 1.25 factor (unless this is a 100% rated breaker and assembly). Two 750 AL is 770 amps. The 800 amp breaker would be ok because of the next size up rule, if your load was under 770.

P.S. also keep in mind there is a good chance the lugs wont take 750

 

[Schmidty0126]

Thanks everyone !

 

[Schmidty0126]

Breaker will accept 750 Aluminum

 

[jumper]

First problem is if the load is indeed continuous, you dont have enough room for the 1.25 factor (unless this is a 100% rated breaker and assembly). Two 750 AL is 770 amps. The 800 amp breaker would be ok because of the next size up rule, if your load was under 770.

P.S. also keep in mind there is a good chance the lugs wont take 750

Yeah, I should have added that I was assuming his load calc had factored the 1.25. Oops.

 

[infinity]

Does the 672 amps already have 125% factored in? If not and it's truly continuous then your 800 amp circuit breaker is also too small. 672*125%=840 amps

 

[kwired]

He didn't mention if there is any non continuous load either, in absence of such and just mentioning of "calculated load" one sort of assumes that is 125% of continuous plus 100% of non continuous load, but OP did say "continuous load" - now we have to verify exactly what he meant before we know how to proceed.

 

[publicgood]

I have a 800 amp 3 pole breaker with trip ratings on breaker installed in a 4000 amp main switch board .The continuous load on the panel being fed by that breaker is 672 amps would parallel 750 Aluminum be allowed to connect to the breaker

How are you coming up with said 672A? We are in winter months and this may not be peak. You need to follow NEC 220.87 if this is existing.