On Fri, 10 Mar 2017 08:16:03 -0800 (PST)
DerbyDad03 wrote:

Oh boy, another ground question. These discussions are always
lively. :-)

I lost power from the wind storm that hit the Great Lakes area on
Wednesday. Last night I borrowed a generator from a friend to get the
furnace going. I simply unhooked the wires from the breaker to the
switch for the furnace and used an extension cord (with the
receptacle end cut off) and wire nutted the hot to hot, neutral to
neutral, and ground to ground from the generator to the wire that
goes from the switch to the furnace. Everything worked fine, other
than the fact that the power came back on less than 3 hours later. It
figures.

Since then, I've done some reading and found these 2 "facts":

1 - I read a generator related post in an HVAC forum that says that
the control board in many HE furnaces require a really good ground in
order to operate properly.

2 - The manual for the generator says:

"Grounding

The generator system ground connects the frame to the ground
terminals on the power panel.
- The generator (stator winding) is isolated from the frame and from
the AC receptacle ground pin.
- Electrical devices that require a grounded receptacle pin
connection will not function if the ground pin is not functional. "

The manual also says that the ground terminal on the power panel can
be remotely grounded by using a ground rod.

So, this indicates to me that I was running my furnace without a
ground, which sort of (sort of) goes against claim #1 that the
control boards need a good ground to operate properly. Of course,
maybe my furnace *seemed* to have been operating properly with the
generator but really wasn't, or maybe my control board doesn't even
need a ground.

Comments?


Skip all that mumbo jumbo and wire a connection to run the whole house.
Easy peasy, but you will need 76 pages of instruction.