Electromatic
Senior Member
- Location
- Virginia
- Occupation
- Master Electrician
Asked to price replacing a generator and ATS. The new generator comes with a 600A breaker. The new ATS is rated at 400A. Already a problem.
Then add, the existing wire (underground in (1)4" PVC) is 400kcmil good for 335A.
I wish at least the generator/switch supplier had some kind of clue. In their defense a bit, the existing generator has a 400A breaker. I'm not sure how the 400kcmil ever passed.
I have a strong feeling that others pricing this job will do so as just a swap with no other alteration. What to do?
The generator breaker is adjustable trip down to 420A, but I can't really see pulling out the 400s and trying to pull in 600s. (about 100' if it were a straight line between the generator and ATS)
The conduit comes out of the slab directly into the existing ATS. I could put a 350A fused switch there and call the 400kcmil an outside tap. Of course, that's ~$1,300 for the switch plus extra labor. Oh well.
Just to make sure, is there ANYTHING that says the generator feeder can be based on the load served or the normal source OCPD? Existing normal breaker is 350A feeding the ATS/load panel.
Then add, the existing wire (underground in (1)4" PVC) is 400kcmil good for 335A.
I wish at least the generator/switch supplier had some kind of clue. In their defense a bit, the existing generator has a 400A breaker. I'm not sure how the 400kcmil ever passed.
I have a strong feeling that others pricing this job will do so as just a swap with no other alteration. What to do?
The generator breaker is adjustable trip down to 420A, but I can't really see pulling out the 400s and trying to pull in 600s. (about 100' if it were a straight line between the generator and ATS)
The conduit comes out of the slab directly into the existing ATS. I could put a 350A fused switch there and call the 400kcmil an outside tap. Of course, that's ~$1,300 for the switch plus extra labor. Oh well.
Just to make sure, is there ANYTHING that says the generator feeder can be based on the load served or the normal source OCPD? Existing normal breaker is 350A feeding the ATS/load panel.