Multiple Conduits versus single with power distribution block

[Duncan8943]

I have 5 Service Entrance rated 200A automatic transfer ATS that will be feeding 5 200A panels in a single structure. A single 300 kva transformer will be used. The original plan was to route 5 conduits from the transformer to each of the ATS units. However, it may be a cleaner job to have one conduit to a power distribution enclosure and go to each of the ATS units from here. What is your preference or how would you do it? Also, I haven't seen a single power distribution block that would work. Any vendor or manufacturer that you could recommend is appreciated. Thanks.

 

[electrofelon]

Generally running multiple sets (whether they are paralleled conductors or multiple sets of service entrance conductors) is more economical since the ampacity does not increase linearly with conductor size. Furthermore, in your case you have the splicing/distribution problem which will not be cheap. The one thing that jumps to mind that may make what you propose worth doing is if the load is small because you could size the single large service conductors to the load not the sum of the OCPD's.... Of course I am generalizing here as I dont know any details, lengths, etc.

 

[iwire]

Is the transformer a utility owned one or a customer owned separately derived system?


If it is customer owned you will have to run five sets of conductors from the transformer. You are not allowed to run a single set and tap it multiple times.

240.21(C) Transformer Secondary Conductors. A set of conductors feeding a single load, or each set of conductors feeding separate loads, shall be permitted to be connected to a transformer secondary, without overcurrent protection at the secondary, as specified in 240.21(C)(1) through (C)(6). The provisions of 240.4(B) shall not be permitted for transformer secondary conductors.

 

[Duncan8943]

New info from utility company

New info from utility company

The utility company owns the transformer. I received their spec for metering which has an enclosure with CTs and power distribution blocks. The spec calls for a maximum of two line and two load conductors. They want a maximum of two conductors going through the CTs. It looks as if I will have to add distribution blocks after the CTs in this enclosure to feed each of the 200A transfer switches.

 

[electrofelon]

The utility company owns the transformer. I received their spec for metering which has an enclosure with CTs and power distribution blocks. The spec calls for a maximum of two line and two load conductors. They want a maximum of two conductors going through the CTs. It looks as if I will have to add distribution blocks after the CTs in this enclosure to feed each of the 200A transfer switches.

You might want to see the equipment to verify how it is setup. In my experience, conductors dont really go thru CTs anymore. they have mounting feet with lugs and the ct's bolt across them and I imagine you could get all sorts of different lug configurations. I recently did a 800 amp service and the utility rep said a single conductor per phase had to be used. Turns out he had no idea what he was talking about. What size is the service and I assume there is only one meter?