Backfeeding your panel with a portable generator

El Rubio · Oct 13, 2010

I recall in one of the older generator threads a discussion on backfeeding your main with a portable. I learned something recently that could be obvious to some but was new to me. As many of you know, there is a bond between neutral and ground in your home electrical system. This is typically at your main panel. If you open the main breaker when you backfeed your panel, it doesn't open the neutral. So the neutral is still connected to ground on the house system even with the main breaker off. A portable generator also has this bond at the power outlet. It's typically a heavy wire between the neutral and ground terminals of the main power outlet. This is a problem because you have the grnd/neutral bond at two locations on the system. This can cause voltage potential on the neutral and ground which can cause problems with electronics or even safety issues. Generators with GFCI breakers will trip because it senses the current flow to ground. The best way to remedy this is to remove the neutral to ground bond at the generator.
The bond will have to be reinstalled if using as a portable such as camping or running stuff on extension cords.
A ground rod is not recommended when backfeeding but you do need a ground connection to your house ground. I have a 4 pole twist lock plug that has separate ground and neutral and ties both in to my main panel. If you park your portable near your home's existing ground rod, it's fine to attach to the same rod but just not separate ones. A ground rod is recommended when the generator is being used as a standalone portable.
I hope this helps anyone who uses a portable to backfeed a house panel.

nickatnite · Oct 13, 2010

So you are an electrician?

SpeedRacer · Oct 13, 2010

El Rubio said:
can cause problems with electronics or even safety issues.

Yup. After Katrina my buddy who's "done it a million times" hooked my generator up to my panel. After about 10 seconds of running I had a surge protector burst into flames, and EVERY piece of electronics I owned that was plugged in anywhere in the house was completely fried.

Call an electrician folks...

El Rubio · Oct 14, 2010

nickatnite said:
So you are an electrician?

No, I work for a wireless communications company and have had detailed training on grounding particular to this subject, plus having to deal with generators during outages. I don't repair generator engines but do troubleshoot issues and delegate to the proper experts. I may repair it if it falls within my expertise, which is electronic, radio, or some electrical.

cajun 22 · Oct 14, 2010

Good info. I have told people for years that a generator does not produce a ground. You have to bring a ground to it for it to be truly grounded. However, most homes will never have a problem with the use of a portable unless there is an existing problem that has not shown itself while on utility power. Surge protector strips are famous for causing this type of problem. I tell people if you must use electronics while on generator power, a power conditioner is the best thing.

The best solution is to install a quick connect terminal on the ground wire on the gen set.

nickatnite · Oct 14, 2010

El Rubio said:
No, I work for a wireless communications company and have had detailed training on grounding particular to this subject, plus having to deal with generators during outages. I don't repair generator engines but do troubleshoot issues and delegate to the proper experts. I may repair it if it falls within my expertise, which is electronic, radio, or some electrical.

So you are NOT an electrician then.

I might suggest that you put that disclaimer at the beginning of your post, so that it would reflect that detail. The grounding you are referring to is clean power vs. dirty power, i.e. using generators as inverters for sensitive, possibly digital equipment, correct?

anyway, IOP1 for when the electricians chime in....

CEHollier · Oct 14, 2010

nickatnite said:
So you are NOT an electrician then.

But he did sleep at a Holiday Inn Express. :rofl:

flamatrix99 · Oct 14, 2010

Calling dantheman..... 1 2 3....

El Rubio · Oct 14, 2010

nickatnite said:
So you are NOT an electrician then.

I might suggest that you put that disclaimer at the beginning of your post, so that it would reflect that detail. The grounding you are referring to is clean power vs. dirty power, i.e. using generators as inverters for sensitive, possibly digital equipment, correct?

anyway, IOP1 for when the electricians chime in....

No, I'm not talking about inverters. I'm not an electrician but know the difference between an inverter and a generator. I'm talking about improperly feeding a structure such as a house with an existing ground/neutral bond. Most portable generators have the same bond as described in the original post. This is a problem, when connected to a house panel. Standby generators will not have this bond unless the transfer switch actually switches the neutral also which isn't common except for places like hospitals.

The grounding I'm talking about is an integral part of your home's electrical system. If you have voltage on the neutral/ground, that means you have less voltage on the hot branch. At some point, electronics such as televisions or computers begin to suffer. It may or may not cause damage but extended use could shorten the life of the device at the very least.

Inverters convert DC to AC and have nothing to do with this discussion.

El Rubio · Oct 14, 2010

cajun 22 said:
Good info. I have told people for years that a generator does not produce a ground. You have to bring a ground to it for it to be truly grounded. However, most homes will never have a problem with the use of a portable unless there is an existing problem that has not shown itself while on utility power. Surge protector strips are famous for causing this type of problem. I tell people if you must use electronics while on generator power, a power conditioner is the best thing.

The best solution is to install a quick connect terminal on the ground wire on the gen set.

Actually, the best solution isn't necessarily connect a ground to the generator. If the ground connection is to the same ground as the house, then it's fine. A separate independent ground rod isn't. A stand alone situation would be better served with a good ground like you suggest.
Sorry if this comes across as pontificating.

themcfarland · Oct 14, 2010

El Rubio said:
Actually, the best solution isn't necessarily connect a ground to the generator. If the ground connection is to the same ground as the house, then it's fine. A separate independent ground rod isn't. A stand alone situation would be better served with a good ground like you suggest.
Sorry if this comes across as pontificating.

It Is good info and I understood just fine..

thanks for sharing..

flamatrix99 · Oct 14, 2010

El Rubio said:
Actually, the best solution isn't necessarily connect a ground to the generator. If the ground connection is to the same ground as the house, then it's fine. A separate independent ground rod isn't. A stand alone situation would be better served with a good ground like you suggest.
Sorry if this comes across as pontificating.

I believe they call it circulating currents going to and from ground.

dantheman · Oct 14, 2010

Doug , I'm staying out of this one . Too many opinions and too many opportunities for something bad to happen .

Metryshooter · Oct 14, 2010

** I'm not an electrician **

If you're going to ground a generator I think it's best to use the same ground rod as the home is grounded to. I don't remember how far they should be away, but I remember being told that if two ground rods are too close together you risk having a ground loop where you don't get a true ground. If this is wrong look at the first line.

simplepeddler · Oct 14, 2010

I AM NOT AN ELECTRICIAN..........
but.......
I have sold electrical supplies, including generators for 26 years. And still do

Please consult an electrician when "backfeeding" .
This electricity stuff can kill you..........really really dead.

Suburbazine · Oct 14, 2010

If a surge protector burst into flames and everything else fried, you should sue your friend for hooking up 1 hot leg in the box to 110 and the neutral leg to the generator's other 110.

nickatnite · Oct 14, 2010

simplepeddler said:
I AM NOT AN ELECTRICIAN..........
but.......
I have sold electrical supplies, including generators for 26 years. And still do

Please consult an electrician when "backfeeding" .
This electricity stuff can kill you..........really really dead.

Same here.
My dad was an electrician and I remember every summer in high school helping him.
Even after he retired from that, people would call and he would refer them to someone he knew.

Even now days, I would consult with a certified electrician on anything of that nature....

nickatnite · Oct 14, 2010

El Rubio said:
No, I'm not talking about inverters. I'm not an electrician but know the difference between an inverter and a generator. I'm talking about improperly feeding a structure such as a house with an existing ground/neutral bond.

Inverters convert DC to AC and have nothing to do with this discussion.

So the Honda and yamaha brand of generators that are also branded "inverters" are not really generators? And with that, you are saying that the Honda Eu6500i inverter/generator that is sitting in my garage that will run my entire house MINUS the a/c is not really a generator? If so, then power that this generator produces is no different than a regular 6,000 watt generator with a Briggs and Stratton motor? As in clean power.

simplepeddler · Oct 14, 2010

Another point about "backfeeding" is that you can put power back on the grid I've been told...........so then you not just take the risk of burning your house down, you take the risk of hurting some poor dude who is trying to get the power back on.

my-rifle · Oct 14, 2010

In a earlier discussion of this topic it was pointed out that if you're going to backfeed, you'd better disconnect your house from the grid first. In my case the main fuse can be pulled, then the house stands alone.

Backfeeding your panel with a portable generator

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