Generator tap conductors

[pgordon]

I have a customer who has 250KW Diesel gen with 3 breakers already installed on it, a 225A, 300A, and 150A. They want to add an additional 400A breaker, there is no room left on the unit to add this to it. Can an enclosed circuit breaker be added to the outside of the unit utilizing the 10' , 25' or the outside tap rule?

I would tap the bussing of the alternator and install the conductors in conduit for physical protection.

 

[ron]

That is a tough question that I've struggled with in the past too. The multiple breakers on the generator are installed by the generator manufacturer or vendor, adding to it violates a listing, because you don't know if there are any limitations that might be imposed by their manufacturing standards.

In reality, if it is an older generator, it isn't UL listed, and maybe reasonable to add another output. The 10' and 25' tap rule is dependent on the upstream protection sizing, which there is none in your case. I'm not sure how you would pick if you decided to do it anyway.