Glenn9643
Veteran Member
Get some cutters and remove the seal from your meter, and then pull the meter from the base. That'll take care of any potential backfeed.
Generator hook up
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klm
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I just can't see how it could possibly backfeed the line if the main breaker is open. You could always check it with a voltmeter.
Highbeam
Super Member
The main breaker only breaks the hot wire, the black one. The other wire, the white one is still connected and in an AC circuit with pushing and pulling there is apparently some risk.
The main breaker only breaks one of the legs.
The main breaker only breaks one of the legs.
1962
Silver Member
i have been plugging into a welder outlet when the power fails too. before i put the generator online i pull the house meter. pulling the meter disconnects the two hot legs, but the neutral leg is still connected. i am sure this practice is not up to code but it works. next time i power up i will check the neutral leg and see what readings i get. /forums/images/graemlins/crazy.gif
TonyV
Silver Member
I've been giving this backfeed thing some thought over the last day or so, and heres my conclusion...I can't see the danger, and heres why. The power coming into your house comes off of a center-tapped transformer. Across the two outside legs of the transformer you've got 220V. From either outside leg to the center-tap you've got 110V. The center-tap is earth grounded. After passing through your meter, both of the outside leges come to your main breaker in the distribution panel. Your distribution panel also has a ground bar which is tied back to earth ground, usually through a 6 or 8 foot grounding rod just outside your house.
When you hook up a 110 volt circuit in the distrubution panel, your hooking the black wire up to one of the outside legs through a circuit breaker, the white wire goes back to earth ground, this gives you 110V. If your hooking up a 220V circuit, then you've got a pair of breakers, one each to the outside terminials of the transformer. The ground wire goes to the grounding bar. Bare in mind here that you've still got 110V relative to the ground wire with your 220 hookups.
Some 220V appliances (like electric dryers) take advantage of using the two seperate 110V sources. Some devices (like welders) use the 220 for the welding circuit, and 110V for things like indicator lights and electronics. (I bet you're wondering where the heck I'm going with all this...patience my friend. /forums/images/graemlins/grin.gif)
Ok, so now we disconnect the main breakers which disconnects the two outside terminals of the center-tap transformer from our distrubution panel. We then plug in a generator to an available 220V socket. That generator provides both outside legs and a supposedly isolated, unearthed ground in much the same way as the transformer on the pole. Since the generator is supplying 110V circuits this puts one side of the 110V potential on the ground bar in the distribution panel, just as the transformer would. This means that one side of the 110V potential is also on the ground out at the pole as well. I believe that this is at the root of the backfeed issue, though in my opinion its an unfounded concern as long as the main breakers are off. The only way that a line worker is going to get zapped is if he got his hands on the other end of the potential at the generator, just the one leg is not going to do it, period.
I think that the reason electricians bemoan this set up is because it IS dangerous....IF you forget to open the main breakers. The proper setup is through break-make switching. When you throw the switch, it disconnects the mains from the pole, and then connects the generator to the panel...much more fail safe. Seems to me this accomplishes the same thing as opening the mains breaker as I don't believe that these switches interupt the earth ground...but we never hear of any backfeed complaints in this case. /forums/images/graemlins/confused.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/grin.gif
Thats my story, and I'm sticken' to it.
...Tony
When you hook up a 110 volt circuit in the distrubution panel, your hooking the black wire up to one of the outside legs through a circuit breaker, the white wire goes back to earth ground, this gives you 110V. If your hooking up a 220V circuit, then you've got a pair of breakers, one each to the outside terminials of the transformer. The ground wire goes to the grounding bar. Bare in mind here that you've still got 110V relative to the ground wire with your 220 hookups.
Some 220V appliances (like electric dryers) take advantage of using the two seperate 110V sources. Some devices (like welders) use the 220 for the welding circuit, and 110V for things like indicator lights and electronics. (I bet you're wondering where the heck I'm going with all this...patience my friend. /forums/images/graemlins/grin.gif)
Ok, so now we disconnect the main breakers which disconnects the two outside terminals of the center-tap transformer from our distrubution panel. We then plug in a generator to an available 220V socket. That generator provides both outside legs and a supposedly isolated, unearthed ground in much the same way as the transformer on the pole. Since the generator is supplying 110V circuits this puts one side of the 110V potential on the ground bar in the distribution panel, just as the transformer would. This means that one side of the 110V potential is also on the ground out at the pole as well. I believe that this is at the root of the backfeed issue, though in my opinion its an unfounded concern as long as the main breakers are off. The only way that a line worker is going to get zapped is if he got his hands on the other end of the potential at the generator, just the one leg is not going to do it, period.
I think that the reason electricians bemoan this set up is because it IS dangerous....IF you forget to open the main breakers. The proper setup is through break-make switching. When you throw the switch, it disconnects the mains from the pole, and then connects the generator to the panel...much more fail safe. Seems to me this accomplishes the same thing as opening the mains breaker as I don't believe that these switches interupt the earth ground...but we never hear of any backfeed complaints in this case. /forums/images/graemlins/confused.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/grin.gif
Thats my story, and I'm sticken' to it.
...Tony
Junkman
Super Member
I, like someone else that is much more knowledgeable than I has been reluctant to get into the fray. I guess that now it is time for me to jump in with both feet. The problem arises when the house wiring isn't to code and the receptacles might be improperly wired. I have seen it happen before, although many will say never. You can purchase one of the testers that you plug into your wall receptacle and it will tell you what is wrong with the wiring or if everything is OK. How many people take the time to check this. I know that the building inspector did when I had the inspection for my generator disconnect. He asked if I checked them all and he also checked a few to make sure.
As for pulling the meter, that is an area that you shouldn't even consider. If you break the seal, then the electric company gets awful upset. People have been known to steal power this way by putting jumpers in place of the meter. A meter socket with no meter in it, can become a dangerous place if a child puts there hand in there.
As for pulling the meter, that is an area that you shouldn't even consider. If you break the seal, then the electric company gets awful upset. People have been known to steal power this way by putting jumpers in place of the meter. A meter socket with no meter in it, can become a dangerous place if a child puts there hand in there.
v8dave
Platinum Member
You don't back feed over the neutral. Like Tony says it's more like forgetting to throw the main switch.
I've had a whole house transfer switch installed by an electrician that specializes in back-up power. It is a two pole switch and only transfers the two hot lines (black). The neutral stays connected--that's the code in my county.
I'm not sure what the NEC says--Inspector, you around?
I've had a whole house transfer switch installed by an electrician that specializes in back-up power. It is a two pole switch and only transfers the two hot lines (black). The neutral stays connected--that's the code in my county.
I'm not sure what the NEC says--Inspector, you around?
v8dave
Platinum Member
I thought some more about this. If you could "back feed" the utility lines after throwing the main switch, the utility could also feed the house ater throwing the main switch off. Now. that just doesn't make any sense. It's an On/Off switch and Off means OFF, not just one direction and not just sometimes.
It really is just a worry about forgetting to turn the mains off when back feeding the house. /forums/images/graemlins/mad.gif No less a worry than having a double male 240 Volt extension cord around the house. /forums/images/graemlins/shocked.gif
It really is just a worry about forgetting to turn the mains off when back feeding the house. /forums/images/graemlins/mad.gif No less a worry than having a double male 240 Volt extension cord around the house. /forums/images/graemlins/shocked.gif
Here is a nice setup from somebody here in TBN http://www.tractorbynet.com/forums/showflat.php/Cat/0/Board/buildit/Number/500848/page/0/view/collapsed/sb/5/o/all/fpart/all/vc/1, I also installed a 220 plug outside my house, discon et the main, turn on gen temp power.
Charolais
Platinum Member
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Guys I work in the wood industry as an electrician. 3 phase and up to 4160 vac. Been doing this for 21 years now.
One example as to how voltage can get past that open double pole main breaker. Through the ground wire. Lots of poles have been in the earth for years. Many have had the copper wire broken above or below ground level. Many homes have a poor ground because of age. I bet if some of you go out and dig to find your ground rod you may be surprised. OK that's the first part. Next if the lines are down. The power co. ground wire may be down as well. Then when you fire that generator up you're running on the ground rod at your house. If it's working proper. If not you're running on the bare copper wires that run down the side of the poles. So if they are in poor condition you can be sending a charge down that ground wire. So it's a very GOOD idea to have a good ground rod connected to your generator which very few folks do. That generator is sitting on wheels, rubber cushions or off the ground on the rear of a tractor. It's not grounded. When you connect the ground wire to your service it's(the generator) looking for and will use that ground if it needs more. When that guy working for the power co. comes in and picks up that ground wire off the dirt then he becomes the ground. Clear as mud /forums/images/graemlins/cool.gif
The code in my county now says you have to break the two hots and the neutral as well on a transfer switch. So that takes a 3 pole switch. In some states now it's required by code that each house have two ground rods.
The next cause is the main breaker. I see this several times a year. Breakers can become welded inside. When you turn it off and one or both contacts are welded you may not notice this or feel it. You think it's off and it may not be. That why us sparkies carry vom meters, voltage glow sticks and test lighted screw drivers. Do not depend on a breaker to remove power. To be safe it must be tested. The main breaker in home services get turned off very little. They can become welded by lightening, a shorted load (like a motor that gone to ground) or with age. That the purpose of a transfer switch. If one of the knives in that switch is welded closed you will know it when you try switch it with the handle. If you back feed a panel and one or both sides are welded close you will feed voltage back to the transformer and it will buck the voltage back up to 7200 or what ever that transformer is rated.
Hope this has helped. Hope I wrote it so it's understandable too. Just got off a 12 hr. shift and had to check cows before leaving and when I got home. It's calving time. Been a lonnnnnng day. That's two ways that back feeding can get you in trouble. I'm to tired to think of the others right now. /forums/images/graemlins/cool.gif Y'all have a good night.
One example as to how voltage can get past that open double pole main breaker. Through the ground wire. Lots of poles have been in the earth for years. Many have had the copper wire broken above or below ground level. Many homes have a poor ground because of age. I bet if some of you go out and dig to find your ground rod you may be surprised. OK that's the first part. Next if the lines are down. The power co. ground wire may be down as well. Then when you fire that generator up you're running on the ground rod at your house. If it's working proper. If not you're running on the bare copper wires that run down the side of the poles. So if they are in poor condition you can be sending a charge down that ground wire. So it's a very GOOD idea to have a good ground rod connected to your generator which very few folks do. That generator is sitting on wheels, rubber cushions or off the ground on the rear of a tractor. It's not grounded. When you connect the ground wire to your service it's(the generator) looking for and will use that ground if it needs more. When that guy working for the power co. comes in and picks up that ground wire off the dirt then he becomes the ground. Clear as mud /forums/images/graemlins/cool.gif
The code in my county now says you have to break the two hots and the neutral as well on a transfer switch. So that takes a 3 pole switch. In some states now it's required by code that each house have two ground rods.
The next cause is the main breaker. I see this several times a year. Breakers can become welded inside. When you turn it off and one or both contacts are welded you may not notice this or feel it. You think it's off and it may not be. That why us sparkies carry vom meters, voltage glow sticks and test lighted screw drivers. Do not depend on a breaker to remove power. To be safe it must be tested. The main breaker in home services get turned off very little. They can become welded by lightening, a shorted load (like a motor that gone to ground) or with age. That the purpose of a transfer switch. If one of the knives in that switch is welded closed you will know it when you try switch it with the handle. If you back feed a panel and one or both sides are welded close you will feed voltage back to the transformer and it will buck the voltage back up to 7200 or what ever that transformer is rated.
Hope this has helped. Hope I wrote it so it's understandable too. Just got off a 12 hr. shift and had to check cows before leaving and when I got home. It's calving time. Been a lonnnnnng day. That's two ways that back feeding can get you in trouble. I'm to tired to think of the others right now. /forums/images/graemlins/cool.gif Y'all have a good night.