Single Phase Backup Generator to Three Phase Mains Supply?

 I have a 6.5kw 220v single phase generator that I want to wire up to
supply backup supply to a couple of offices in my house. The mains
supply in the house is three phase 220v...
Is there a way to wire this up? Something like an isolator/generator
switch on one of the phases (as long as the offices are on the same
phase)? I don't want to go to the additional expense of purchasing a 3
phase generator or a single to three phase converter but would like
backup power into the office circuits. I'm not too concerned about
have the entire house on the generator but do need the offices....
Thanks

  On Mon, 21 Jan 2008 23:26:14 -0800 (PST), chriscapetown@gmail.com wrote:


Yes, it's possible.  You'll need a three pole transfer switch.  A manual switch
will
be FAR less expensive than an automatic switch.

The details of the connection will vary a little depending on whether you have
true 3
phase service (120/208) or split delta (also sometimes referred to as a Wild Leg
configuration) (120/240) service.  For residential use with lots of single phase
loads, you probably have split delta.

In general, the incoming utility is connected to one set of stationary contacts
and
the house is connected to the moveable contacts on the transfer switch.  Then you
identify which two of the three legs feeds your 120/240 volt single phase loads
and
hook the two hot legs of your generator to those two stationary contacts on the
other
side of the transfer switch.  The generator neutral goes the to panel's neutral
and
is not switched.  Ground goes to ground.

There is a complication to this setup if you only have one breaker panel.  Three
phase loads will be energized with single phase only.  To avoid that, you'll
have to
remember to flip the breakers on all the three phase loads before using the
generator.

If, as is fairly common, there is a three phase panel and a single phase panel,
the
situation is much simpler.  Simply insert a regular single phase 2 pole transfer
switch in the connection between the three phase panel and the single phase
panel.

If you don't have separate single and three phase panels then you might consider
having a separate single phase panel installed as part of the generator
installation.
The money you save by using a single phase transfer switch will pay for a good
part
of the conversion cost.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com  <-- best little blog on the net!
Tellico Plains, Occupied TN
Multitasking: Reading in the bathroom!