5- 100 amp disconnect switches& 100 amp panels

[pelican]

5- 100 amp disconnect switches& 100 amp panels

I would like to mount 5-100 amp disconnect switches on a rack at the base of a pole with a 50 kva TX on it. Each switch would then serve a 100 amp panelboard at a house. The Rio Power Co. would come from the secondary of their 50 kva Tx to their secondary junction box mounted directly underneath the Tx. I would tie into this junction box with 15 # 4 cu THHN conductors and run them down the pole in 2.5 conduit each to their 100 amp disconnect switch. I would build a trough on the top of these switches. The conduit/cables would come in the side of the trough. Because of NEC mutal conductor heating I have to do an ampacity limit, which says cables between 10-20 reduce by 50% so that means in my 100 amp disconnect switches I have to put 50 amp fuses? I am trying to come up with an inexpensive way of going UG not using padmounted Tx's. That's why this is unorthodox. Thanks for your previous help on this issue.

 

[jerryb]

Re: 5- 100 amp disconnect switches& 100 amp panels

Re: 5- 100 amp disconnect switches& 100 amp panels

There's no problem here. You only have a 50 kva transformer which can only provide 208 amps. That would divide equally amoung 5 houses @ 41 amps each.

But if you want 100 amp services, then don't put all your wire in one conduit. Typically a utility is not governed by the NEC, so why don't you run one set of 500 kcmil down the pole, into a trough and tap that for each fused switch.

 

[iwire]

Re: 5- 100 amp disconnect switches& 100 amp panels

Re: 5- 100 amp disconnect switches& 100 amp panels

Jerry what does the size of the transformer have to do with derating or not.

The transformer can provide much higher current then it is rated for.

I do not understand how this service is being built.

Where are the meters?

Why disconects at the pole, are these mobile homes?

Bob

[ July 22, 2004, 06:35 PM: Message edited by: iwire ]

 

[a.wayne3@verizon.net]

Re: 5- 100 amp disconnect switches& 100 amp panels

Re: 5- 100 amp disconnect switches& 100 amp panels

Bob sometimes we encounter situations like I did in that church in Oklahoma.The building was built after the meter and non fused disc.combo unit was set by the POCO.I met it with 4/0 sec
and an isolsted direct burial ground cable assy.On the building I mounted a 200 amp w.p. disc. , back to backed to a 200 amp 40 ct. panel.4 wired from the POCO to the 2nd disc.That`s a secondary system,so it`s code compliant Then went home it was wired , trimmed and done deal after the fact..

 

[pelican]

Re: 5- 100 amp disconnect switches& 100 amp panels

Re: 5- 100 amp disconnect switches& 100 amp panels

I will request/suggest Rio Power Co. mount their meter below the secondary junction box on the pole. Come out of the box with 500 mcm into the meter and out of the meter with 500 mcm into the trough. Then tap the 500's for each feed to each 100 amp disconnect.Thanks for your help.