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Here’s a puzzler for an electrician —
I was asked, at a client’s recently acquired summer farm house, to hook up some outside wires that had been previously chopped off and capped with tape. Wires consisted of 3 cables, two #2 stranded alum.(120 V each) and one # 4(?) stranded alum. as a common; no ground wire. All are controlled by a 100 amp breaker in the house’s breaker box.
My multimeter showed 120 volts on both “hots”, so I wired them into a 120 volt load center, slipped in a 1-pole 30 amp breaker, and grounded to a 5/8″ copper stake. My client wanted 2 GFCIs added in a 4-plex, so I wired those, using #10 Romex. I plugged in a reciprocating saw for a final test, and nothing happened.
The GFCI tester said “open neutral”, so I re-checked and tightened all the cables. But wait !! Testing at the clamps in the load center now showed 70 VAC in the left+common and 170 VAC in the right+common position; 70 + 170 = 240; OK, now what? Clearly, I had wired a voltage divider, no?
First I changed the 30 amp breaker to the other pole, which simply reversed the 70/170 anomaly. Then, I put in a third new GFCI; I poked the re-sets again and saw the indicator flash on. I next removed the downstream GFCI (having by then heard not to wire two together) and substituted a standard 3-prong recepacle as the second in line; the GFCI’s “load” contacts now connect to the receptacle. Still no success, except I get 120 volts crossing either hot+ground combo in the receptacles. Maybe be a common problem….
I’ve checked and rechecked; wired and rewired, tightened again and cussed a lot. The house breaker box doesn’t appear to have a main on/off lever, so I’ve delayed looking inside for a loose common wire. Is that what will I find when I finally look? If that’s not it, how can I get this seemingly simple fix to function appropriately? Any ideas will be sincerely appreciated. Thanks. — RLQ
Replies
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You have to check the Voltage at the source .. so you need to pull the cover off the main panel and check to see what is happening there. I would check it both with the wires on the breaker and the wires off the breaker. I am thinking you have a break in your line from your main panel to your subpanel. BTW you should have two hot 120s, one neutral, and a ground coming from your main. If not, it is time to replace this feeder. In addition, you should have a ground rod at the remote subpanel
*Well, I see we have what appears to be an uncertified Black Angus attempting the precarious moon jump...As to the outcome...the possibilities do seem endless!Lets call this one...Back to the stream,aj
*First, if "The house breaker box doesn't appear to have a main on/off lever" you need to get an electrician out to correct that as soon as possible.That is a very serious safety concern.Second, I think you shouldn't be doing the stuff you're doing without opening the panel.Call an electrician NOW
*Bobby buddy... the old small panels were legal without a main as they had small groups of breakers that could be swatted to off all at once. I worked on one a few years ago when I did a camp addition.As to whether the angus gets hung up on the moon cheese... all bets are off!wearing my hardhat near the stream,aj
*Measure your voltages with a light bulb on each line -- open circuit voltage with 10Mohm meter only says something hooked up. AJ: we need a photo insert of the type of "moon" you mean, really getting cranky on sparky questions these days. Sparky quiz for today: You just installed a fancy surge arrestor/noise filter for your new computer, computer runs fine, but you double check the voltage at the computer plug with a meter (say a good quality accurate/calibrated meter such as the Fluke 77 for completeness on the quiz) and you read 140 VAC!!! What's up???Hint: put a scope on the line. Answer tomorrow or Friday.
*ARt... we needs a new issue and site...i FineElectricwiring...with Jolt-time for sharing our shocking tales.near the jolting stream,aj
*The voltage problem is most likely a loose neutral, either in the cut feeder wires you are working with, in the main panel feeder wires, or in the feeder from the utility. To check these, you will need to open the main panel. Sounds like you need an electrician.Also, general purpose receptacles should not be wired on a 30A circuit, only 15 or 20 amp. A 30A circuit would require 30A rated devices.
*Good point.For as long as I am aware, the NEC had specified that you had to be able to disconnect all service in the building with no more than "6 hand motions."There was disagreement about whether swiping a bunch of breakers at once with the side of your hand should be considered "one hand motion" so in the last revision or 2 that was changed to read "no more than 6 breakers to disconnect all service" (or words to that effect.)At least in my area, I see very few 100 amp boxes without a main disconnect; I see a few "split" bus boxes where one breaker controls the branch circuit sub busses and 2, 3, or 4 others control the furnace, range etc.I have seen a couple of 20 breaker 100 amp panels with no main disconnect which could be ok if you accept the (now discredited) hand swipe interpretation. I told my clients that it was probably considered OK when installed but it is questionable and for a small investment in a main disconnect the system can be made safer.The main point is that I don't think he should be using some random wires which had been chopped off without opening the panel to see what the heck is going on inside it. Maybe they were chopped off because they were no longer needed; maybe they were chopped off because the system had some sort of major problem on that circuit and "chopping it off" was the prior homeowner's idea of how to "fix" the problem.
*RQL, Are you an electrician? If not think of the repercussions if something was to go wrong!AJ, I see your reply's on this board lots and know you don't advocate people doing their own electrical work, I am wondering if you are an electrician yourself?bake
*RQ,This is the classic symptom of a loose neutral, as others have said. My guess is that the break is underground--that's why the cable was abandonded in the first place.See Redwood Kardon's "Code Check Electrical" checklist for a nice explanation of how a 240V circuit with a bad neutral becomes exactly what you called it--a voltage divider. Redwood has much of that checklist up on the web. Try a search under the title, or go to the Taunton Press website (Taunton.com).Why'd you use a 30A breaker to protect a standard receptacle outlet circuit? That's a future fire danger, and a Clear Code violation. Also, is the "120V load center" (which I have to assume is 120/240 or two pole panel) in a building?If it is, and if there's any metallic path (water or gas pipe, phone or CATV wire) between the building with the service and the building in which you installed the subpanel, there HAS to be an equipment grounding conductor run from main panel to subpanel (in addition to the hots and neutral). This is to provide a low-impedance return path for ground fault current to the main panel, to open the feeder breaker; otherwise, the fault current may wind up on the phone or coax, or water pipe. Bad news--a real life safety hazard. Best of luck. I suggest you review the residential Code. In some cases, a little knowledge is a very dangerous thing.Cliff
*I read and reread the original post. Could it be that this was a 240v circuit with NO nuetral? From the wire size it seems so. Also, the lack of a main disconnect "lever" may not be an issue IF it has a main breaker rather than an external cutoff lever
*Yes... residential. I take care of most of my clients electric needs from small projects to new construction.I am not for teaching over the internet all the details contained in ones head to safely work with main panels. Yaa...if they just need a bit of the info, but not the whole 2 year course. As to typical little problems...Some yes...some no... some... time to start talking about the cows coming home.near the the fence petting Bessey May,aj
*#2 aluminum may not be a suitable wire for 100 amps.Aluminum is not be suitable wire for a beginner.2 hots and a third wire is suitable for a subpanel.As they say in New Hampure -- Learn fast or die.
*RLQ, You have no neutral and not enough respect for electricity.No shame in admitting you're in over your head,but a sin to keep going anyway.
*What Barry said.
*Warning... this post makes no sense at all.
*Agree with Gunner and Barry
*Many thanks, Ladies & Gentlemen -- Yes, I have already recommended that the owner call an electrician. And yes, I also consulted an electrician before doing what I did for the owner; BTW, two electricians have now been puzzled by this situation, which is why I'm here at Delphi consulting the wisest of the electrical oracles. -- RLQ
*Find the guy who did it. Or find an older electrician. ie. one who doesn't need daipers or if he does make sure they're depends.
*Sometimes the effort and labor to save some abandoned thing is hardly worth it. I don't know how long this cable run is, but I bet it is only a few dollars compared to what he could burn down.When in doubt, tear it out.
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Here's a puzzler for an electrician --
I was asked, at a client's recently acquired summer farm house, to hook up some outside wires that had been previously chopped off and capped with tape. Wires consisted of 3 cables, two #2 stranded alum.(120 V each) and one # 4(?) stranded alum. as a common; no ground wire. All are controlled by a 100 amp breaker in the house's breaker box.
My multimeter showed 120 volts on both "hots", so I wired them into a 120 volt load center, slipped in a 1-pole 30 amp breaker, and grounded to a 5/8" copper stake. My client wanted 2 GFCIs added in a 4-plex, so I wired those, using #10 Romex. I plugged in a reciprocating saw for a final test, and nothing happened.
The GFCI tester said "open neutral", so I re-checked and tightened all the cables. But wait !! Testing at the clamps in the load center now showed 70 VAC in the left+common and 170 VAC in the right+common position; 70 + 170 = 240; OK, now what? Clearly, I had wired a voltage divider, no?
First I changed the 30 amp breaker to the other pole, which simply reversed the 70/170 anomaly. Then, I put in a third new GFCI; I poked the re-sets again and saw the indicator flash on. I next removed the downstream GFCI (having by then heard not to wire two together) and substituted a standard 3-prong recepacle as the second in line; the GFCI's "load" contacts now connect to the receptacle. Still no success, except I get 120 volts crossing either hot+ground combo in the receptacles. Maybe be a common problem....
I've checked and rechecked; wired and rewired, tightened again and cussed a lot. The house breaker box doesn't appear to have a main on/off lever, so I've delayed looking inside for a loose common wire. Is that what will I find when I finally look? If that's not it, how can I get this seemingly simple fix to function appropriately? Any ideas will be sincerely appreciated. Thanks. -- RLQ