# Backfeeding a circuit with no power



## MHElectric (Oct 14, 2011)

There have been a couple of threads here about troubleshooting a circuit without power by backfeeding it off another. Ive been too sckeeered to try it becuase I havent wanted to accidentally have a phase-to-phase short. Until today...

We had a call with power out in a few rooms house and we get in there a start troubleshooting. I find where the power stops in the living room and decide to backfeed the rest of the room/circuit off of it. (At this time we had a few recetacles and switches out and hadnt found any burnt or bad backstabs, and nothing that showed any signs where the circuit had lost the hot or nuetral.) So we jump a temporary piece of wire from plug to plug to see where weve lost power at, and as soon as I touch the hots together...booom!!! Dangit!! I pulled my temp jumper off and ran to check the breaker...not tripped...hmmm...go back to the room and now the part of the circuit that had been dead is up a running, but it turns out it was tied to a different circuit than the one I backfed it on. I had shorted both phases together. 

So, now everything is working, but I have no idea why this fixed the problem, so I procede to opening up all the receptacles and switches on this circuit to see if I can find one where maybe it was burnt up or had lost power in thie first place. Nothing.....nothing at all, everything looks cool and checks out fine. Im still scratching my head at this point, but the problem was fixed and the customer was happy. As were packing everything back up in the van I shot a glance over at my helper, and he looks like he has no idea what the heck just happend. I got a good laugh at his face and later on the best explaination I could come up with for him, was this: more than likely, a hot had lost a good connection in one of the receptacles or joints and when we backfed it, the conection was probably melted together :confused1: and this caused the circuit to come back on......at least this is my best guess..???

Anybody here who uses this backfeed trick have any ideas, or a better explanation than the one I came up with?


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## erics37 (May 7, 2009)

I don't backfeed a circuit unless I identify and isolate the piece of wire that went bad (usually rodents or a siding nail or something), eliminate the possibility of it being energized by hacking it off as far in the wall as I can reach, and then re-run that portion of the circuit.

Instead of guessing, you could have found where you lose your connection with a decent toner device. Jumping random circuits together isn't a good idea, what if you tie two circuits together from different breakers on the same phase? Then when someone goes and turns the breaker off, it's still energized?


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## MHElectric (Oct 14, 2011)

erics37 said:


> I don't backfeed a circuit unless I identify and isolate the piece of wire that went bad (usually rodents or a siding nail or something), eliminate the possibility of it being energized by hacking it off as far in the wall as I can reach, and then re-run that portion of the circuit.
> 
> Instead of guessing, you could have found where you lose your connection with a decent toner device. Jumping random circuits together isn't a good idea, what if you tie two circuits together from different breakers on the same phase? Then when someone goes and turns the breaker off, it's still energized?


 Yeah..well, :whistling2:

Truth be told, I was postive (notice I say WAS) that it was the same curcuit cause we jumped it off another plug in the same room! 
I wasnt thinking that everything in this room, but that one plug, was going to be fed from another circuit. I have troubleshoot this exact house layout (late 70's early 80's 1100 sq ranch home) at least a dozen times around town and I got ahead of myself be thinking that I knew it already.

I dont think Ill use this backfeed trick again.


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## MHElectric (Oct 14, 2011)

Judging from your response, Let me be a little more specific on how we backfed the cicuit. 

We just used a temp piece of romex from plug to plug in the room. We did not fish wire inbetween the receptacles, tie in and make a joint. This would be the same as having any old extension cord you plugged into one rec and then tied it to the other. It was just to see where we had lost power at.


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## jimmy21 (Mar 31, 2012)

erics37 said:


> I don't backfeed a circuit unless I identify and isolate the piece of wire that went bad (usually rodents or a siding nail or something), eliminate the possibility of it being energized by hacking it off as far in the wall as I can reach, and then re-run that portion of the circuit.
> 
> Instead of guessing, you could have found where you lose your connection with a decent toner device. Jumping random circuits together isn't a good idea, what if you tie two circuits together from different breakers on the same phase? Then when someone goes and turns the breaker off, it's still energized?



When i was about a 3rd term apprentice, my company was working on this HUGE mansion of a house. Ridiculously rich lady that kept making this job drag on forever. There were low voltage switches, panels, contractors, relays, photocells. Nightmare of a lighting system When it got close to being completed she decided she was going to throw a party for all her rich friends. Somebody told the lady that all the lights would be working on friday night. It was not looking like its going to happen so they brought in some extra people on to the job. That's where i came in to the picture. A couple hours before people start arriving, the lights still aren't working. The apprentice, that had been working on the job for the last couple of months, started going around wire nutting circuits together. "that circuit has power, this one needs power. Nut them together" I tried to explain to him why this was a HORRIBLE idea. That if a photocell or whatever turns that circuit on it could be a phase to phase short and start blowing up expensive equipment. Plus he made that nightmare system that much worse. Not to mention he did nothing to the neutrals. Never did hear about what happened, but ive thought about that for a long time


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## erics37 (May 7, 2009)

jimmy21 said:


> When i was about a 3rd term apprentice, my company was working on this HUGE mansion of a house. Ridiculously rich lady that kept making this job drag on forever. There were low voltage switches, panels, contractors, relays, photocells. Nightmare of a lighting system When it got close to being completed she decided she was going to throw a party for all her rich friends. Somebody told the lady that all the lights would be working on friday night. It was not looking like its going to happen so they brought in some extra people on to the job. That's where i came in to the picture. A couple hours before people start arriving, the lights still aren't working. The apprentice, that had been working on the job for the last couple of months, started going around wire nutting circuits together. "that circuit has power, this one needs power. Nut them together" I tried to explain to him why this was a HORRIBLE idea. That if a photocell or whatever turns that circuit on it could be a phase to phase short and start blowing up expensive equipment. Plus he made that nightmare system that much worse. Not to mention he did nothing to the neutrals. Never did hear about what happened, but ive thought about that for a long time


Rich people and their fancy, unnecessary gizmos in their houses need to get fed to the lions.


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## chicken steve (Mar 22, 2011)

MH,
your two best options are to backfeed, or tone out as Eric said

we will backfeed, but we will make a male cord cap/ xtention cord off a kitchen or bath gfci to do so, especially if we have all the devices out of the wall(s)

the tone out we do often needs the main shut off , more a safety issue digging through spaghetti circuitry really

I have best results working a circuit from source on out, but in either scenario, i would suggest 'mapping' or 'numbering' on out

~CS~


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## McClary’s Electrical (Feb 21, 2009)

Read potential between the two next time first.


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## Dennis Alwon (May 9, 2009)

I have never had a need to back feed. Sounds like you had a bad connection in a receptacle and the jolt moved it. Just because there is no burn mark does not mean there wasn't a loose connection. My bet is the connection will be lost again.


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## MHElectric (Oct 14, 2011)

Dennis Alwon said:


> I have never had a need to back feed. Sounds like you had a bad connection in a receptacle and the jolt moved it. Just because there is no burn mark does not mean there wasn't a loose connection. My bet is the connection will be lost again.


Petty much what I thought.


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## Southeast Power (Jan 18, 2009)

I am not sure what could be discovered by back feeding a circuit but I suspect that a screw is in the cable and you just maybe welded it back for the time being. 
I would have connected a toner to the dead outlet an followed it back to the break. I just picked up a toner a year or so ago and can't believe how good of a troubleshooting tool they are.


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## k_buz (Mar 12, 2012)

Years ago, I was at an older couple's home for power out to a circuit. I spent about 3 hours there taking stuff apart, checking and remaking splices to no avail. Came back with my boss the next day (hoping a fresh set of eyes would make a difference) and we found a switch literally behind the range that was turned off when the cleaning person was dusting. Apparently this circuit was wired to this switch.

I guess what I'm trying to say is that I know your resistance to simply backfeeding the circuit.


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## Shockdoc (Mar 4, 2010)

My ex boss did that, and a few days later we found ourselves back there again, the last visit i traced the wire to a three way backstabbed outlet behind the china closet.


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## RGH (Sep 12, 2011)

I carry a gfi jumper I use for service change over power..then back feed with that in line...had one of these a few months ago...60's home..addition built later...FP panel...builder or someone tapped garage cir. (20) for family room (14 awg) and a kit recp (20awg)....and of coarse out door recp.... back-stab burnt through....PITA was behind china cabinet....last place I looked...but she was baking cookies...:thumbup:...btw the fp 20ocd didn't trip...they had a space heater on/tv/computer/lights/microwave.....my old equation : back stab=future work=$$$


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## jimmy21 (Mar 31, 2012)

RGH said:


> I carry a gfi jumper I use for service change over power..then back feed with that in line...had one of these a few months ago...60's home..addition built later...FP panel...builder or someone tapped garage cir. (20) for family room (14 awg) and a kit recp (20awg)....and of coarse out door recp.... back-stab burnt through....PITA was behind china cabinet....last place I looked...but she was baking cookies...:thumbup:...btw the fp 20ocd didn't trip...they had a space heater on/tv/computer/lights/microwave.....my old equation : back stab=future work=$$$


What good is a gfci going to do in this situation?


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## RGH (Sep 12, 2011)

jimmy21 said:


> What good is a gfci going to do in this situation?


depending on the issue this is the safest way to start....if gfic trips this indicates a short...it cir powers up a burn thru...last thing you want is arching in a wall....I am not a big fan of this method....it is quick and dirty and works ...old school


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## Tiger (Jan 3, 2008)

I did something similar. A neutral was lost so I ran a circuit from the panel to the middle of a circuit but it went to the same circuit breaker. In your situation I'd be afraid that the connection would be lost again and I'd be stuck doing a free warranty.


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## dthurmond (Feb 7, 2011)

I bought a fluke toner about 6 months ago and had not used it until today. It works great and I should have bought one several years ago.


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## Big John (May 23, 2010)

Never done it, and I don't think I've ever seen it done. Seems like a strange method of troubleshooting: What is the backfeed supposed to tell you, other than being a temporary solution?

-John


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## RGH (Sep 12, 2011)

Big John said:


> Never done it, and I don't think I've ever seen it done. Seems like a strange method of troubleshooting: What is the back feed supposed to tell you, other than being a temporary solution?
> 
> -John


..quick and dirty way to find approx location of problem a.b.c working...e.f.g. working (when back feed)...problem between c.d.e...(c) don't show burn through so work both ends to the middle...my experience with these problems is usually line break from nails from pics ect..or a old kink burnt thru in wall...rodent damage in wall ....exterior nails pounded thru from decorations....mundain chit to them but $$$ for us...had one a year ago 3 way to garage stopped working....gutter spike...feed was up around top of a door and down to sw.....damn roofers...$$$$:thumbup:


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## jarhead0531 (Jun 1, 2010)

In my opinion back feeding is both dangerous, and dumb. There is never a reason to back feed a circuit.

Too many electricians focus on the devices that are not working, me I look for the device that is working and wiggle that sucker around with my plug in tester. 9 times out of 10 I can find the problem outlet in the first 5 minutes. 

I'd say I've been to 5 or 6 houses in the last year where I show up, find the problem, and have it fixed in 10 minutes before they tell me about the other electrician that was there yesterday for 5 hours and left without charging because he couldn't fix it.

For the tough ones, you can't beat a toner though. Found many a buried junction box with that sucker.


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## sbrn33 (Mar 15, 2007)

IMO backfeeding is not a viable method of troubleshooting.


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## RGH (Sep 12, 2011)

jarhead0531 said:


> In my opinion back feeding is both dangerous, and dumb. There is never a reason to back feed a circuit.
> 
> Too many electricians focus on the devices that are not working, me I look for the device that is working and wiggle that sucker around with my plug in tester. 9 times out of 10 I can find the problem outlet in the first 5 minutes.
> 
> ...


toner..great tool...as I said before back feed is an old school way to bug out a problem..dangerous and dicey at best...I am not a fan...90% in resis chit problems are devices...or methods....just like back handing the stuff we have today has made things easier/safer/faster.....the back feed is a lazy way out...you can do the same trick with 50' extension cord and a fluke:thumbsup:


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## Big John (May 23, 2010)

RGH said:


> ...a.b.c working...e.f.g. working (when back feed)...problem between c.d.e....


 Honestly, it just sounds like the odds of that happening are slim. Seems like more often than not, you'd power everything up, there'd be voltage in front of and behind the fault, and--unless you deliberately picked the opposite leg to backfeed with and started looking for 240 between devices--you'd never see anything.

Just seems like there are more effective, less risky ways to locate a failure. 

-John


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## nrp3 (Jan 24, 2009)

I don't mind the idea of refeeding from somewhere else to avoid damage to existing walls etc, that is once I know I have found the problem, know I can't fix it, and like someone else said, cut out the bad piece at both ends so it can't be used again. Not going to do it blind without knowing what is going on.


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