Mark wrote:
On Feb 28, 9:45 pm, "Jon" wrote:

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

This is my design, it *will* work, I ordered the parts, it meets my needs, I
ordered the parts and it's what I'm going to do.

All I care about is protecting the generator. The coil has to be energized
24/7 to do it, but there's no other way.

* if the generator isn't feeding power to the house and barn, it means we
forgot to turn off the main switch and we are feeding power into the grid.


As I see it, with this system power will not ever be fed back into the
grid, anytime there is power at the "service" terminal the generator
will be disconnected by the NC contacts and the ignition will be
killed by the NO contacts...

Wrong. It will feed power back to the grid *EVERY* time the grid power
is restored with the mains switch still on and the genset running.
When the mains power is restored, it will take some period of time
for the relay to move the contacts off of the N/C position. During
that brief period the genset will be connected to the grid. That
period, no matter how brief, contradicts "not ever".

His ONLY means of "not ever" feeding power back to the grid with
his hairbrained scheme is to trip the main breaker. Even then, note
that he is tapping power from the service panel BEFORE the main
breaker, which itself is a serious hazard. A short from genset
output to the signal wire will feed power out via the signal
wire, even if the mains breaker is tripped. So even with the
main breaker tripped, we cannot accurately state that power
will not ever be fed back to the grid.

And there's more. What happens when the N/C contacts weld? Or the
N/O contact goes open? Or the coil fails? Or the unfused signal
wire shorts to ground? Or goes open somewhere between the mains
and the relay?

Ed




Mark