2-2-4 SER

[kwired]

What is capacity of generator?

Never mind, assuming you are talking 100 amps as mentioned in OP. Inspector may be correct, if it is protected with a 100 amp breaker.

 

[upstatecontractor]

20kw

20kw

generator is 20kw - with a 100 amp breaker in the genset which feeds a 200 amp ats which is service rated. what about the use of SER inside and the use of the 60 degree column for conductor ampacity>?

 

[augie47]

generator is 20kw - with a 100 amp breaker in the genset which feeds a 200 amp ats which is service rated. what about the use of SER inside and the use of the 60 degree column for conductor ampacity>?

That's am much debated discussion here. 310.15(b)(6) vs 338.10. If your AHJ allows, take advantage of the situation.
One thing you might check is that many generator manufacturers call for Cu only at there termination.

 

[hurk27]

I have often wondered if the exception to 445.13 could be used when the actual current the generator can produce is lower then the rating of the breaker on it, many gen sets have electronic current limiting to prevent from burning up the generator, some are just by design not able to produce more current because the motor will start to stall out, but we all know in the case of a fault wither line to line or line to ground that smaller conductors will take the fault since the OCPD will open fast, what if the generator has built in over current protection, can we adjust to this using the exception when the only thing the 100 amp breaker does is protect for faults? a 20kw generator will only produce 83 amps so why do we have to size the conductors + 25% to the 100 amp breaker and not to the actual current the generator is capable of? also many gen-sets will have a reduced rating when run on NG verses propane, so can we use this lower rating when sizing our conductors? do we really need to size off the breaker on the generator when the rating of it can be much lower?

Just kind of throwing this out, so don't take it as a can do.

 

[Smart $]

generator is 20kw - with a 100 amp breaker in the genset which feeds a 200 amp ats which is service rated. what about the use of SER inside and the use of the 60 degree column for conductor ampacity>?

Assuming this is an optional standby unit, the compliance issue which needs covered here first is 702.5(B). The gist is when using automatic transfer equipment, the calculated load cannot be greater than the generator's rated capacity. Otherwise you will have to use some means of load shedding (or a generator with greater capacity).

 

[ceb58]

I have often wondered if the exception to 445.13 could be used when the actual current the generator can produce is lower then the rating of the breaker on it, many gen sets have electronic current limiting to prevent from burning up the generator, some are just by design not able to produce more current because the motor will start to stall out, but we all know in the case of a fault wither line to line or line to ground that smaller conductors will take the fault since the OCPD will open fast, what if the generator has built in over current protection, can we adjust to this using the exception when the only thing the 100 amp breaker does is protect for faults? a 20kw generator will only produce 83 amps so why do we have to size the conductors + 25% to the 100 amp breaker and not to the actual current the generator is capable of? also many gen-sets will have a reduced rating when run on NG verses propane, so can we use this lower rating when sizing our conductors? do we really need to size off the breaker on the generator when the rating of it can be much lower?

Just kind of throwing this out, so don't take it as a can do.

Another interesting observation. But your statement about size of conductor + 25% is misleading. If the generator has a breaker built on then 445.13 doesn't apply. So it looks as if 240.4 may be it.