A water heater is in the garage about 6 feet from a window.
There is a 3 wire cable to the water heater +120 -120 and a bare wire
grounded to the frame. No separate white neutral.
A generator sits at window level with ther exhasust extended though a
'dryer vent' type arrangement and is available for emergency power
within a few minutes.
The generator frame is grounded to the outside ground in the earth.
I was thinking of using a 20 foot 3 wire cable to the dryer receptacle
like we did during Hurricane Jeanne but I considered the following:
MAIN DISCONNECT IS OFF!! it is off, it is OFF!!!! (no way is it ON!)
One hot wire going from the panel to the water heater goes to the
center terminal of SPDT switch. The other panel wire goes to the water
heater and to one generator wire.
Water heater on one end of the SPDT and generator on the other.
1> Using the SPDT we break the wire to the heating elements and
switch it to the generator.
2> I use the generator to back feed the panel 240 VAC.
3> If I wish to heat water at 120VAC I connect the open water heater
wire to ground.
Generator ---------------------------------: (generator lead A
permanently connected to water heater wire #1)
Panel -120 ----------------:-water heater wire #1 connected
Panel +120--------- --\\ ------------ water heater wire #2 open
Control Switch SPDT \\-------- (generator lead B connected)
Panel ground_______________Generator Ground and generator Neutral
Switch in GENERATOR Mode feeding Panel 240 VAC
When switch is thrown, generator B is open and watewr heater wire #2 is
connected to panel (normal power on position)
Should I wish 120 VAC heating with GENERATOR, short water heater wire
#2 to ground wire (no neutral available in cable).
Just 2 single pole switches and we would be on backup generator with a
choice of slow (1/4 power) hot water.
NOTE* The Generator cable has a 4 conductor male plug and it is not
plugged in until the Main Breaker is OFF!
The cable will be plugged into a dummy receptacle until just before
using because one lead is 'hot'.
Any negative consequences to the above wiring idea?