On Sunday, September 10, 2017 at 2:56:59 PM UTC-4, trader_4 wrote:
On Sunday, September 10, 2017 at 1:57:00 PM UTC-4, Fred McKenzie wrote:
In article ,
wrote:
Got a portable generator recently. Would like to eventually wire in a
transfer switch for my house and run a few selected rooms. My generator has
the neutral bonded to the frame. You are also supposed to ground the
generator frame. Seeing as it's portable they tell you to pound a grounding
rod into the ground and wire your ground lug on the frame to that.
I'm going to jack it into my house, so I think I can just use the same ground
that runs through my house. Every 120V outlet will have a ground connection
so getting to this ground be easy with a custom cable or modified extension
cord.
If I ground my generator to the same ground that the power company provided
to my house, I believe I can use a standard 2-Pole transfer switch that does
not have the special third pole to switch my house circuits over to my
generator neutral....basic transfer switches just connect the neutrals
together (house and generator). So that's what I want to do. House Neutral
is connected to Generator Neutral. House Neutral is also bonded to House
Ground (by the power company, not me) and Generator Ground (frame of
generator) is connected to house ground (this one by me). I think this
avoids all the problems with ground loops and GFIC outlets on the generator
tripping....
I can't see why this doesn't work BUT there are articles all over the
internet describing this problem. I've not seen this simple solution
mentioned. It's always you need to buy a special and more expensive transfer
switch or you need to modify your generator and remove the ground-neutral
bond. It seems to be a source of great confusion.
Can anyone see a problem with method I'm describing?
CW-
You do not need to switch the generator ground, but you do need to
disconnect it from the frame when connecting to your house system.
Whether you can do it or not depends a lot on the generator. Some make
it nearly impossible to separate ground from neutral. Others have a
short green jumper wire from one outlet's ground to the frame.
I get around the problem by not connecting into the house system. I run
a heavy extension cord from the generator into the house. Only a few
lights and appliances get plugged in. In an emergency, I figure lights,
a microwave, a refrigerator and a coffee maker are all that I need.
My refrigerator keeps ice frozen for at least 8 hours, so I do not run
the generator while asleep. That saves gas and the generator is less
likely to be stolen!
Fred
What is the benefit to disconnecting the frame from the ground at the generator? I can see one big negative, the frame is now ungrounded and if a hot wire in the generator comes in contact with it the frame is energized. Touch it and the return current path is through you, through earth, back to the house grounding electrode. Am I missing something?
I figured out the issue and the problem. As I see it, the issue isn't
the frame being disconnected from ground, it's the issue of whether the
neutral at the generator is tied to ground or not. If the generator
neutral is not tied to the frame and not otherwise earthed, then the
system relies on the house neutral and earth ground connection and it
meets code. You have one path for the neutral current to flow between
generator and house, that's in the neutral conductor in the cord used
to connect the two.
If the neutral at the generator is connected to the frame
then you have three paths for neutral current to flow between the
generator and the house. One is via the neutral in the 3 conductor
plus ground cord used to connect, which is the desired path.
Another is via the ground wire in that cord. The third is via earth.
That's the problem, you're now putting neutral current where it
shouldn't be, mainly it will be split between the neutral and the
ground wire.
Also, if the neutral is not connected to ground at the generator,
then the generator frame should and must still be grounded to the system
by the ground wire (eqpt grounding conductor) in the cord used
to connect to the house.