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SERVICE

LINE1 LINE2
120v 120v
o o
| |
| |
*-------(A)-------*
| |
| |
* *
\ DISCONNECT \
\ \
* *
| |
| |
| |
| |
| |
o o

LOAD

o o
| |
| |
--- C --- C
--- ---
| |
| |
| |
| *---------*---------*
| | | |
| | | |
| | --- A --- B
| | --- -/-
| | | |
| | | |
| | (B) (C)
| | | |
| | | |
| | --- ---
| | - -
| |
| |
| |
| |
| |
o GENERATOR o


A is a mercury relay with a 240vac coil.
B is a N.C. 120vac coil with 30amp contact.
C is a dpst 120vac coil with 90amp contacts

When the disconnect is ON and the service is either ON or OFF,
* the generator is isolated from service feed
* the generator cannot backfeed into the grid

When the disconnect is OFF and the service is ON
* the generator isolates from the load

When the disconnect is OFF and the service is OFF
* the generator is connected to the load

The generator can't work or be damaged unless the disconnect is OFF.

I designed this circuit around some parts I had. The disconnect is in the
breaker box.

On Thu, 3 Jun 2010 01:16:05 -0400, "Jon" wrote:

view in courier
...

Why don't you just do it right the first time?

We keep telling you what is required, there are tons of schematics on
the web, all it takes is two relays (power contactors), a small SPDT
switch, and a bit of time. WTF is so hard about doing it right?