Generators - Backfeeding - 120V

[JB4310]

We are on 17 acres...the nearest neighbor is retired and we have no kids. Unless my dog grows a thumb, she won't be using my very short double ended cord.

I don't believe there is a possibility to backfeed power down the lines with the breaker off. I have seen these new interupts that are just a piece of steel screwed to the cover of your CB panel and it prevents the main breaker from being turned on and allows the BF circuit to then be turned on. If that system is legal...what is the electrical difference to what I am doing?

Generator InterLock Kit

The interlock is a fail safe system and is legal, in other words it's idiot proof.

Remembering to shut off and lock out the main is not.

Put a LOTO box on the end of the cord (both plugs into it if possible) and lock it. That will keep people out of it and remind you of what it is before you use it.

Aaron Z

Good idea,

JB

 

[grsthegreat]

Only if your two generators happen to be exactly 180 degrees out of phase, which is so unlikely as to be essentially impossible.

/QUOTE]

Who said anything about two generators. ??

For the OP running 110 to both sides of the panel will power all circuits as well as give 220.:thumbsup:

Note: I still arn't an elecrician.

NOPE. unless the gen CAN put out 220, just hooking up both outlets from a 110 gen WILL NOT result in 220 power. I agree that all you have to do is move the upstairs breakers to the phase of the panel that is powered up....easy, done deal. As long as you dont need 220, it wont matter.

 

[grsthegreat]

OK I am not an electrician either, but I have read, either on this forum, or another one, somewhere, that even if you turn off your main breakers, there is a chance of power backfeeding into the system, through the ground.

.

If not, I'd really like to know what the safe way to hook up a generator is, besides running everything off an extension cord.

Nope, that wont happen. Even a residential grade transfer switch does not isolate the grounds or the neutrals. As long as the 2 hot legs are isolated, its safe.

NOW, i am not going to say i approve of this lock out tag out system, cause i am a licensed electrician and if i was to install the system you just mentioned id probably have my license yanked.

 

[grsthegreat]

On the diagram showing how to connect a transfer switch legally in our state (KY), it shows the utility power coming in to one set of lugs, auxiliary power coming in to the other set of lugs, and the set of hots coming from the switch going to the panel. These are all separate and can only be connected by changing the position of the switch, thus avoiding the chance of backfeeding the utility power.

However, all of the neutrals from the utility, auxiliary, and panelboard are all on the same lugset, as well as the ground from the panelboard. So it doesn't appear (to me) that there is an opportunity for the utility to be backfed from the ground or neutral (our neutrals and grounds are bonded in the panels - I don't know if this is different in different areas).

I tried to upload the diagram showing this (a .tif) but I get a "invalid file" error.

100% correct.....the neutrals are not isolated or disconnected in a residential transfer switch. I have seen them disconnect in big commercial 3 phase units, but never on a residential unit.

 

[Canada_CT230]

People aren't reading my posts correctly.

1) I know its not legal. Nor is speeding, rolling stop signs and having a few too many beers and driving that people do. Hence why I'm not discussing the legality of it.

2) I am a commercial pilot. Very well and used to doing things the same way the 100,000,000th time over and safely too. I'm not an idiot and can get past the world's reasons to design for the lowest common denominator.

3) I do NOT need 220V.

Now, I may be able to swap around some breakers to try and move some to the powered leg but this still might not work as I have NO room for expansion in the CB panel. Hence why I can't put in another line, breaker....blah...blah, etc.

I just need to know if I can power both legs of 120V to get 120V at outlets and light fixtures.

 

[sparc]

For all those that do need 220 and don't want to run a suicide cord, you might want to look into a Generlink transfer switch. www.generlink.com
I have no connection to Generlink, but I am in the process of getting one for my home.

 

[aczlan]

I just need to know if I can power both legs of 120V to get 120V at outlets and light fixtures.

Yes, in a theoretical world where you do it the same every time and nobody else will ever touch it, it will work.
But, if you get sick and your neighbor comes over to help or whatever and someone forgets to turn off something that uses 220v, it will do bad things to your generator or the 220v appliance.

Aaron Z

 

[grsthegreat]

People aren't reading my posts correctly.

1) I know its not legal. Nor is speeding, rolling stop signs and having a few too many beers and driving that people do. Hence why I'm not discussing the legality of it.

2) I am a commercial pilot. Very well and used to doing things the same way the 100,000,000th time over and safely too. I'm not an idiot and can get past the world's reasons to design for the lowest common denominator.

3) I do NOT need 220V.

Now, I may be able to swap around some breakers to try and move some to the powered leg but this still might not work as I have NO room for expansion in the CB panel. Hence why I can't put in another line, breaker....blah...blah, etc.

I just need to know if I can power both legs of 120V to get 120V at outlets and light fixtures.

the answer is .....no. you'd have to do some rewiring to power both legs of a 2 leg system off of one leg. Get some split mini breakers and add some breaker spaces to the leg thats under generator power. you'd have to rewire both sides of the panel together and do it thru a breaker powerful enough to handle the combined load. I could do it...but i wouldn't.

In an airplane i guess you could try to force a autolite sparkplug into the engine cause you cant afford a proper aviation spark plug......but would you do it???

 

[gpflepsen]

Pull the plug to a high amperage 220v outlet, like to the dryer or range. Make a jumper plug to put a short across the powered lugs that are normally 220v.

Or, at a high amperage 220v breaker, remove the circuit wires and place a jumper wire across the terminals to feed the other leg. Size the jumper wire accordingly.

 

[quicksandfarmer]

I just need to know if I can power both legs of 120V to get 120V at outlets and light fixtures.

You can, but it is a dangerous thing to do. It is very common for both legs to share a neutral. This only works because normally the two legs are out of phase and don't both draw at the same time. If you connected both legs to the same source they would be in phase, and the neutral would be handling current from both. The neutral would be overloaded without either circuit breaker tripping, and it could easily overhead and start a fire.

A much better solution is to move all of your essential circuits onto the same leg.

 

[JB4310]

People aren't reading my posts correctly.

1) I know its not legal. Nor is speeding, rolling stop signs and having a few too many beers and driving that people do. Hence why I'm not discussing the legality of it.

2) I am a commercial pilot. Very well and used to doing things the same way the 100,000,000th time over and safely too. I'm not an idiot and can get past the world's reasons to design for the lowest common denominator.

3) I do NOT need 220V.

Now, I may be able to swap around some breakers to try and move some to the powered leg but this still might not work as I have NO room for expansion in the CB panel. Hence why I can't put in another line, breaker....blah...blah, etc.

I just need to know if I can power both legs of 120V to get 120V at outlets and light fixtures.

I'm not the safety police, just trying to get you to do what you want safely. Not criticising or judging. I gave you my answer that yes you could do it, but gave you the one example of a problem that could possibly result with shared neutral circuits (probably wouldn't be a problem for just lighting loads).

Pull the plug to a high amperage 220v outlet, like to the dryer or range. Make a jumper plug to put a short across the powered lugs that are normally 220v.

Or, at a high amperage 220v breaker, remove the circuit wires and place a jumper wire across the terminals to feed the other leg. Size the jumper wire accordingly.

Interesting and would work super easy, but that's getting even more Frankensteinish, more to remember to undo after.

Though it may be better than 2 male/male cords going to different rooms in the house to power both sides of the panel. Got me also thinking of some kind of custom cord to feed thru that 220 outlet, so he could hit both sides thru one source. Basically a jumper with the male 220 on one end and 2 male 110's on the other. I know that's a Frankenstein setup as well :confused2:

JB

 

[Canada_CT230]

I don't want to do any conveluted wiring (in the dark). I want a simple 1-2-3 system.

I think I will try to move a few circuits to the live side and be done with it for now.

 

[JB4310]

You can, but it is a dangerous thing to do. It is very common for both legs to share a neutral. This only works because normally the two legs are out of phase and don't both draw at the same time. If you connected both legs to the same source they would be in phase, and the neutral would be handling current from both. The neutral would be overloaded without either circuit breaker tripping, and it could easily overhead and start a fire.

A much better solution is to move all of your essential circuits onto the same leg.

Oh, very good point, I already warned him of the shared neutral issue, as I recognised that as a potential problem with the neutral being overloaded, But I didn't even think about the fact that the breakers would not be overloaded, and would not trip, possibly causing a fire.

Not all houses have those shared circuits but my house does have several.

If he did have them he would really have to be careful not to exceed 50% load on those circuits.

JB

 

[tsteahr]

All this discussion about frying the neutral, starting a fire, blowing up a panel, etc is true in theory. But lets remember the OP has a 3000W 120v generator. He has 25 amps or less available. Regardless if this 25 amps is split over one hot leg or two, the neutral will still only see a max of 25 amps. This is not going fry anything.

Just trying to keep some perspective here...

 

[radioman]

Its just easier to have a manual transfer switch panel. Super easy to install yourself. you just pick the circuits you want and pull out of old breakers and connect to new panel that is the transfer switch. No need to worry about 220, no need to worry about backfeed, no need to worry about shutting down gen when power comes back on and you will know its back on from circuit you havent transferred over.

I realize it sounds complicated from my statement, but trust me, its super easy. for 300 bucks or less like this one Shop Reliance 7500-Watt Transfer Switch Kit at Lowes.com .

I installed one after one time power went out and I BF in house with main breaker off and I realized I had no way of knowing when power is back on unless i shut down and switch main back on. So I went out and bought a transfer switch. its worth every penny since I can only power which circuit I wanted ahead of time and still know when power is back on without worry about backfeeding to one lug only or remember to shut off main.

 

[JB4310]

All this discussion about frying the neutral, starting a fire, blowing up a panel, etc is true in theory. But lets remember the OP has a 3000W 120v generator. He has 25 amps or less available. Regardless if this 25 amps is split over one hot leg or two, the neutral will still only see a max of 25 amps. This is not going fry anything.

Just trying to keep some perspective here...

Could get a little warm if it was all going thru a 15 amp 14 ga shared circuit.

But I agree, that would not be very likely, that his entire draw would be thru 2 circuits.

JB

 

[aczlan]

Though it may be better than 2 male/male cords going to different rooms in the house to power both sides of the panel. Got me also thinking of some kind of custom cord to feed thru that 220 outlet, so he could hit both sides thru one source. Basically a jumper with the male 220 on one end and 2 male 110's on the other. I know that's a Frankenstein setup as well :confused2:

If you insist on doing this, the safest way is probbaly to get a 20 amp 220v breaker. Wire in your 20 amp outlet into one side of the breaker with 12 gauge wire and run a jumper from that side of the breaker to the other using at least 10 gauge wire.
Then when that breaker is on, you will feed both sides of the bus, but if you forget to turn it off, the wire will hopefully hold up to the current long enough to trip the breaker. I would recommend that at very least, you get one of those sliding interlocks so that it is physically impossible to backfeed the line to the road.

If you need to free up some spaces to make this work, there are double mini breakers available for most panels that will let you relocate two circuits to make space for your frankenstine setup

Here is a basic wiring diagram:

Please note that I do NOT recommend powering both legs of your breaker box with 120v in this fashion, but if you must do that, this is probbaly the safest way to do it.

Aaron Z

 

[crazyal]

It's very easy to do. Do you have a 220 outlet you can plug your generator into (yes I know you don't want 220, just follow me). If you connect up both 'hot' wires together and then to your 'hot 110 leg from your generator you'll power both sides. If you really want to do this I would put a fuse or circuit breaker in the middle of the jumper between the two hot legs.

If you don't have a 220 outlet you can make a second cord and use the second outlet on the generator. Just find two different outlets that are on different legs.

I'm not the safety police so I'm not going to tell you if you should or shouldn't connect a generator up to your house wiring without using a transfer switch. However if you did add in a transfer switch you could wire the same way and get 110 to both legs. Also with a transfer switch you wouldn't need to worry about the one in a million chance of someone turning on the main breaker with the cord and jumper or the two cords connected up (even with the generator off it'll still short both legs together).