Hey all.

I have a questions relating to a generator installation. I have a customer with a really rather large house that wants completely automatic standby power. Lights go out, generator fires, can go about using the complete house as if nothing happened. Currently there is an underground service coming from a pad mounted transformer at the property line with a CT meter at the trans. Two 4” PVC conduits come into the basement into a trough. In each conduit are 3-600’s alum. I believe it’s a 800a 120/240 service. I say “believe” because there is no main switch/disconnect stating an amperage size. What happens is, on the trough are three 200 amp 42cir panels and one 200a disconnect feeding a panel elsewhere in the house. One of the conduits coming from under ground has three wires - two hots and a neutral. The second conduit has the same thing naturally. Seems to me it would be parallel, however they never meet in the house. Conduit 1 cables each go to a splice block and feed out of the block with two 3/0 and feed two panels. Conduit two cables each go to a splice block and feed out with two 3/0 and feed the other 200a panel and the 200a disconnect. Is this a correct use of parallel conductors? I assume they leave the same lug at the trans but they never reconnect at the house, they stay split. I always understood they needed to be connected at both ends, but I may learn something here.

That being said I need to get these into an automatic transfer switch. I was planning on making them true parallel and disconnecting them from the splice blocks, feed double barrel lugs on line side of a transfer switch and then feed out with a quad lug on the load side of the transfer switch with 3/0 and hit each panel. The transfer switch is going to be big with 800a feed through’s and probably 400a or 600a emergency feed.

I’ve set a few 600a - 2000a generators and transfer switches over the past few years in commercial, but this residential rework install has be a bit stumped on a few things. So here are the questions.

Is the current parallel setup legal? It will probably disappear so the answer is more for knowledge than the install.

Can I feed a service rated transfer switch and then feed out to the panels and not have a main switch/disconnect? I think I can do this because I don’t have more than 6 mains after the transfer switch. One option would be to order a transfer switch with a built in main if need be, but that could take months.

If I come off the load side of the transfer switch with a quad tap to feed panels am I now into the tap rule? Which one 10’ or 25’?

I want to feed directly into the transfer switch and directly to the panels from load side. I can’t imagine ordering switch gear with a 800a main switch and 4-200a breakers and installing it a basement to make this thing work or is this my only option?

The generator looks like it will be about 15’ off the back of the house. (yes, I told them it will be like having a small truck parked next to the house, but it’s ok with them. At least until the thing exercises a few times.) Do I need a disconnect at the house for the emergency feed?

Any help to these questions or other issues you see from my description would be very helpful. I have some thoughts to my questions, but need to hear your opinions.

Thanks