Grid Tie 240 VAC w/ transfer switch? [RE-wrenches]

Chris Daum info at oasismontana.com
Thu Aug 9 07:58:27 PDT 2001


Hi Joel and others:

I live in a remote part of western Montana, and do not have the luxury of 
meeting face-to-face with most of the electricians, contractors, 
brothers-in-law, or homeowners who install the components I've sold to 
them.  I have systems all over the world, and I work out the details by 
e-mail and faxes, providing wiring diagrams and tech support as needed.  I 
try to keep my basic designs simple, for minimal hassle, ease of 
installation, and have had relatively little troubleshooting (thank god!) 
to do.  Most of my systems are off-grid.  I have also helped out folks 
who've had systems put in by others, and have had problems--but I only do 
so much of that without assessing a fee.  I am probably one of those 
"dot-commers" y'all dislike, but I have many, many happy customers.  And if 
they want a local service person who can sell, install, and do it all, I'm 
happy to refer them to one of you.  I'm quite busy, as I'm sure you all 
are, and I don't expect a return for the favor--to me it's just common 
sense.

Anyway, many thanks to Bob-o, Todd, Allen and Jeff  for your helpful 
comments.  My customer wants to upgrade his 100A entrance service to 200A, 
so maybe I can talk him into utilizing his old 100A service as a separate 
sub-panel for his inverter loads. I like recycling!

Regards,

Chris Daum
Oasis Montana Inc.
406-777-4321 or 4309
406-777-2632  fax
http://www.oasismontana.com


-----Original Message-----
From:	Joel Davidson [SMTP:joeldavidson at earthlink.net]
Sent:	Thursday, August 09, 2001 8:12 AM
To:	RE-wrenches at topica.com
Subject:	Re: Grid Tie 240 VAC w/ transfer switch? [RE-wrenches]

Most of us get together with other designers face-to-face to discuss system
design over sketches, block diagrams and drawings. How can RE-Wrenches
facilitate electronic collaboration on systems like these?

"Bob-O Schultze, Electron Connection" wrote:

> Chris,
> ASSUMING (because you don't say) that your customer wants a manual
> switch (else how would he know he had an outage and to "power down"?)
> and that he has a 200A service, you could put in a manual 200A DPDT
> or 3PDT switch. Two cautions. One, they are a big mother, far bigger
> than a separate service panel, so what's the point? Two, you'll have
> to have the utility power the house down or work getting the feeders
> into the switch hot. Doable, but a little scary. Feeding a dual 60A
> CB and can from the utility side of the switch to the AC1 inputs
> should be no problem IF you can find a way to do it without sticking
> your #6 wires in the same lug as your 200A (probably 4/0 AL) feeders.
> That would work but be a NEC no-no.
> Bob-O
>
> >Dear Wrenches:
> >
> >My client's system is in California; he has two Bergey XL 1's on order, 
and
> >has two Trace SW4024's and six 120W modules.  He is in a place with 
rolling
> >power outages and wants back-up (vis a vis eight of the Surrette S460
> >batteries).  His power is rarely out for more than an hour at a time. 
 His
> >site offers excellent sun and winds, with 15 to 18 mph averages.
> >
> >But, he doesn't want a separate sub-panel for his important loads.  Has
> >anyone done a grid-tie with a transfer switch (located before the main
> >electrical service panel), where one side of the transfer switch is from
> >utility power, and the other leg is 240VAC from the inverter's output? 
 My
> >client wants total back up not just dedicated loads, and says he'll 
"power
> >down" in the event of a power failure (and yes, I've cautioned him that 
if
> >the grid fails, it would be easy to max out his inverters). There is no
> >fuel generator integrated into this system.
> >
> >I've talked with a nice fellow from Asco (http://www.asco.com) about
> >whether their transfer switches would work for this application.  We 
both
> >think it would--but know of no one who's tested or tried this.
> >
> >One thing I'm uncertain about, code-wise, is feeding the utility input 
into
> >the AC 1 "in", from the utility side of the transfer switch (like, with 
a
> >separate 60A circuit breaker).
> >
> >Anybody got any ideas or experience with this type of system?  I'd
> >appreciate any advice you could offer.
> >
> >Chris Daum
> >Oasis Montana Inc.
> >406-777-4321 or 4309
> >406-777-2632  fax
> >http://www.oasismontana.com
>
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