Thanks, Mark, for answering William's question. You took the words right out of my mouth.
But I wonder if William can get away with a 100A transfer switch, since it is only a 100A service. I guess it would be up to the inspector. S/he might be concerned to somebody could upgrade the service at some time in the future, and not upgrade the transfer switch, but I would think that that would be the fault of the person doing the service upgrade, not William's. But as we all know, inspectors can be quirky. But then there is the issue of the 82A generator output. 82A x 1.25 = 102.5A Brian Teitelbaum AEE Solar From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Edmunds Sent: Thursday, April 30, 2009 9:34 AM To: RE-wrenches Subject: Re: [RE-wrenches] 3 Xantrex XW system Hi William - the 200A rating is to allow for the fact you may have 48A of pass through from the grid to the critical loads with the normal 60A breakers in the system. Mark From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of William Miller Sent: Thursday, April 30, 2009 8:35 AM To: RE-wrenches Subject: Re: [RE-wrenches] 3 Xantrex XW system Brian: One more question: Why must the external transfer be "rated for at least 200 amp?" The utility feed is 100 amp, the generator is 82 amp and if my arithmetic is correct, the inverters can generate 75 amps. William At 10:00 PM 4/28/2009, you wrote: William, In the Xantrex "XW Power System Installation Guide", pages 2-34 to 2-37, there is a parts list and some diagrams on the wiring of a 3-inverter system. The parts list calls for two 5 ft (62" hole-to-hole) 4/0 battery cables to connect the third inverter up to the Distribution Panel. Also shown is the use of an external bypass switch to make up for the lack of enough AC breaker spaces in a single Distribution Panel. It shows a breaker/interlock panel, but a 2-pole manual transfer switch will also work. Either way, it should be rated for at least 200A. Brian Teitelbaum AEE Solar
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