Generator backfeeding into utility lines

[955Lincoln]

The code requires that any device used with the service equipment be "service rated". It has a higher ground fault capacity that the individual branch circuits. If you do know what all this means take my word for it as it is too technical for this forum. So if you are doing the switch selecting of either utility power and generator power at the main breaker level "whole house system" then that is the service entrance. I am trying to make a "licensed electrician" knowledge level something you can understand. It is all about your safety. If you have a sudden fault to ground things can virtually explode and cause a fire or worse if you are in front of it.

This dialog is very important to understand when dealing with heavy commercial/industrial applications or things such as large pumps and compressors.

A more recent issue is arc fault protection. You will encounter this if you do a new installation or major retrofit such as your panel replacement. All bedroom circuits now have to have arc fault circuit breakers. There is a lot to know in the electrical business. It is not for novices.

Of course you all by now should know about ground fault devices in circuits, either at the breaker or the outlet. That is discussion for a different forum as this one also should be.

Ron

Thank you very much, your first 2 sentences answered my question. It's raining heavily now and I need to go and test my outdoor GFI outlets.

 

[Tractor Seabee]

Thank you very much, your first 2 sentences answered my question. It's raining heavily now and I need to go and test my outdoor GFI outlets.

Is your outdoor circuit GFCIs in the outdoor box or in an inside receptacle and daisy chained to outside? Unless you are in the desert those GFCIs located outside will not last long, they corrode and fail to trip. Real problem where I live. Testing often is a good practice either way. Get a good quality tester not your body to ground.

Ron

 

[ultrarunner]

Actually, I think "Telegraph" poles where here first.

A better term is probably "Utility Pole"

Telegraph from the 1840's... now long gone... although many cities still have roads by the name of Telegraph Ave...

Telephone from the 1870's and still with us today...

Some of the original creosote poles in service more than 80 years...

 

[955Lincoln]

Is your outdoor circuit GFCIs in the outdoor box or in an inside receptacle and daisy chained to outside? Unless you are in the desert those GFCIs located outside will not last long, they corrode and fail to trip. Real problem where I live. Testing often is a good practice either way. Get a good quality tester not your body to ground.

Ron

Touche....

It's inside BTW

 

[timswi]

As a side note to backfeeding the house...I'm just curious as to why my motor home is factory built to backfeed the 5K generator back into the coach using the AC source cord with no transfer switch, just a closed circuit. If it's so dangerous to do that, why would Gulf Stream design it that way?

This has nothing to do with the grid, obviously....I just noticed some saying this was bad for the house in general.

 

[grsthegreat]

As a side note to backfeeding the house...I'm just curious as to why my motor home is factory built to backfeed the 5K generator back into the coach using the AC source cord with no transfer switch, just a closed circuit. If it's so dangerous to do that, why would Gulf Stream design it that way?

This has nothing to do with the grid, obviously....I just noticed some saying this was bad for the house in general.

I guess i dont know what your talking about. My motor home had a switch that said utility, off, generator. It was a manual trip toggle switch. I have no idea how yours works.

 

[timswi]

I guess i dont know what your talking about. My motor home had a switch that said utility, off, generator. It was a manual trip toggle switch. I have no idea how yours works.

AC feed cord plugged directly into the 220 box coming out of the generator..Of course all of this is in the cord storage box. It's a straight-up backfeed by design. It's a '97, but still.

The generator will just idle away unless the AC cord completes the circuit.

 

[grsthegreat]

AC feed cord plugged directly into the 220 box coming out of the generator..Of course all of this is in the cord storage box. It's a straight-up backfeed by design. It's a '97, but still.

The generator will just idle away unless the AC cord completes the circuit.

If the trailers normal extension cord is simply plugged into the generator OR the house outlet, this IS NOT a backfeed situation, as you cant possibly have it plugged into both at the same time.

 

[timswi]

If the trailers normal extension cord is simply plugged into the generator OR the house outlet, this IS NOT a backfeed situation, as you cant possibly have it plugged into both at the same time.

The AC cord is plugged directly into the generator, it's really no different than plugging the generator into a 220 plug in the house. The recep it just a straight 220 feed from the generator.

Maybe we're saying the same thing.

 

[955Lincoln]

The AC cord is plugged directly into the generator, it's really no different than plugging the generator into a 220 plug in the house. The recep it just a straight 220 feed from the generator.

Maybe we're saying the same thing.

The big difference here, your generator is in effect "the power company". If you were to take another generator and try to hook it up it would be more in line with this thread. Trying to hook both generators up at the same time could toast one or both.

 

[timswi]

The big difference here, your generator is in effect "the power company". If you were to take another generator and try to hook it up it would be more in line with this thread. Trying to hook both generators up at the same time could toast one or both.

That's what I said originally. The coach itself is being backfed.....Somehow I'm not saying this right, no one is following me. I'm only referring to backfeeding the house, not energizing overheads, I'm fully on board with that danger.

 

[955Lincoln]

Perhaps it's the words that you are using. Think of your generator as the power company like I mentioned. You are not backfeeding unless you try to hook up another generator by plugging it into a wall outlet or 220 volt circuit on the coach.

 

[timswi]

Perhaps it's the words that you are using. Think of your generator as the power company like I mentioned. You are not backfeeding unless you try to hook up another generator by plugging it into a wall outlet or 220 volt circuit on the coach.

I follow you...My thought on backfeeding is when you pump power into a facility from an external source outside of the utility...Even when there is a "hard" break from the utility...Be it a downed line or a redirected AC cord....

I was trying to refer to the issue of powering a house et.al. from a quasi stable AC source..ie. a portable generator. Even though the generator in the MH is permanent, it's still a de facto portable generator. Some were saying that the power stability from portables could cause damage to the electrical system...I don't know, maybe I've gone over the cliff on this one.

 

[grsthegreat]

The AC cord is plugged directly into the generator, it's really no different than plugging the generator into a 220 plug in the house. The recep it just a straight 220 feed from the generator.

Maybe we're saying the same thing.

Its major difference cause the trailer plug ONLY feeds the trailer, a cord from a generator to a house can be fed thru to the power lines/transformers.

 

[Qapla]

When the power coming into the panel from the source (be that power company, generator, or some other way) enter through the "main", the house (or camper, trailer or whatever) in being "FED" - not Back-fed"

When you introduce power through a "circuit" in the panel, you are "Back-feeding" the panel. In other-other-words, the power is coming "IN" where it should be going "OUT". When this is done, the "Main" should be turned off to prevent the new power from leaving the panel through the "main connection"

In the discussion here, the term "back-feeding" was being used to indicate that the generator was connected through a breaker in the panel not the main. It was then extended to refer to the condition that results if the main is not turned off ... thus, "back-feeding" the power lines running to the panel.

Hope this helps.

Now, for some of those here that understand electricity and the problems that can result ... please see my post "Shocking! Can you help?"

 

[orezok]

I guess it's like picking up a gun. If you don't assume it's loaded every time, someone might get hurt!

I'd be willing to bet that 99% of you always check to see if there is a round in the chamber before you handle it. A lineman who doesn't check the "chamber" is subject to a Darwiin.

 

[mjym]

hi im a retired lineman and if you use a generator you better put a little more off your money and install the right breaker so that everybody would be safe backfeeding was a nightmare for us it dont thak much to kill a man .5amp and your toast hope that you will fallow my advice thanks mario

 

[Tractor Seabee]

Yep, that's that 220V gen set becoming 12,470V when it goes thru the transformer on the utility pole backwards

 

[RonMar]

Yep, and any load transformer connected to that HV line will try and absorb all the energy that your puny little backup generator can produce, just like it was power from the utility on the line. Is your generator large enough to power ALL your neighbors? Cause that is what it will try and do This will promptly try to stand your little generator on it's ear, and pop it's circuit breakers if you are lucky... The danger happens if the local line in your neighbor hood is down or otherwise disconnected from any other loads, then you can have an energized line from your generator(potential, but no current flow). Add into that a lineman who has been scrambling for the past 20-30 hours trying to get peoples lights back on and perhaps getting a little careless trying to be quick for a demanding public, or someone who dosn't understand how dangerous a downed line can be, and you have an incident.

Best to use a transfer switch, an isolated backup loadcenter, or an interlocked backfeed breaker that physically makes it impossible to have the main breaker and the backfeed breaker on at the same time. You will sleep better at night

Test run those gennies, winter is comming!

 

[sparc]

Or look into using a Generlink.

www.generlink.com