AC electrical puzzlement

[Curt Harms]

This morning I plugged in a small electric heater for the bathroom. No sign of life, figured it was either the heater or outlet. I turned off the circuit breaker (after I found it, panel is poorly labeled), removed the outlet and began poking around with a meter. Black to white was 0 volts, I was thinking tripped GFCI. Nope, the outlet that is part of the GFCI is alive. When I checked black to ground and white to ground (bare wire), they both read 125 volts . I have not done anything electrical for months so I don't think it's anything I did. The CB was labeled 'outside outlets' so I checked both of those today and they're dead as well. One of outdoor outlets worked yesterday, I was using it to power some lawn equipment. The cord that powered the lawn equipment is unplugged.

I haven't opened up the outdoor outlet enclosures yet, that's next. Does anyone have any thoughts about why both conductors would be carrying 125 volts to ground? I'd have thought if something came loose either one leg would be dead or it would have shorted out and tripped either the GFCI or circuit breaker.

When I replaced the outlet in the bathroom I found the wires were back stabbed. Not with clamps on the back of the outlet, just stabbed into the back of the outlet. I wasn't exactly pleased to find that. The replacement is wrapped around the screws. Everything in the house is functioning as expected except for this one circuit.

[Tom M King]

How many wires in the box? Just one of each?

[Tom M King]

Is anything plugged into any if the outlets in that circuit? Black and white wires are connected wrong somewhere.

[Cameron Wood]

Did you try plugging the heater into a known good outlet? Did you try another appliance in the bathroom outlet?

The most likely issue is a tripped GFCI. The backstabbed receptacle suggests that it is not a GFCI one, and that it is in a bathroom that it is GFCI protected, so there would be an upstream GFCI outlet or a GFCI circuit breaker.

It could be the same circuit as the outdoor outlet.

If there is another load on the circuit the you tested, it could explain the reading. There is another explanation as well. Using a multi-meter on household electrical stuff can sometimes be misleading- too sensitive.

Occasionally the circuit breaker can be on and has power to it's terminal screw, but the wire is loose and not making contact- checking that the circuit breaker screws are tight is a good idea.

[Rod Sheridan]

A broken, or disconnected neutral wire will cause portions of the the neutral circuit to be energized.

Regards, Rod.

[Lee Schierer]

I would de-energize the circuit. Then check each and every device known to be on that circuit to see if any are still energized. If so de-energize that circuit as well. Then starting at the GFCI location open the box and check all the wiring to insure it is properly connected and tight. If any of the receptacles are in a box with another make sure the screws from one aren't contacting the one next to it. Check each outlet in sequence until you locate the problem.

[Dan Friedrichs]

A broken, or disconnected neutral wire will cause portions of the the neutral circuit to be energized.

Regards, Rod.

I think Rod's got it. You have a disconnected neutral, and there is something plugged into an outlet somewhere else on the circuit, causing the hot and neutral to be at the same potential.

Unplug every load that could possibly be on that circuit (including any lights, etc) and see if the 120V on the neutral disappears. That would confirm that you have an open neutral connection.

[Tom M King]

Then open every box on that circuit and test where you have 120 between the black and white. Probably something as simple as a loose wire nut in the white wires or even a bad receptacle device.

It’s a fairly common problem with the old back stab receptacles. Bad connection in one of them. Shake the wires because it makes it very hard to find one that completes the circuit when you move it.

If they are back stabbed, I would just change every receptacle in that circuit.

[Rich Engelhardt]

This sounds like it might be a case of reversed polarity.
They sell little plug ins that you use to check outlets for things like that.
https://www.gardnerbender.com/en/p/GFI-3501/Ground-Fault-Receptacle-Tester

[Ole Anderson]

This sounds like it might be a case of reversed polarity.
They sell little plug ins that you use to check outlets for things like that.
https://www.gardnerbender.com/en/p/GFI-3501/Ground-Fault-Receptacle-Tester
Yes, this. Inexpensive and if you just plug it into a three prong outlet, will tell you if it is wired correctly, and if not, what the issue is.

[Tom M King]

You can get them in the box stores too.

https://www.homedepot.com/p/Klein-Tools-GFCI-Outlet-Tester-RT210/206517824

[Dan Friedrichs]

This sounds like it might be a case of reversed polarity.
They sell little plug ins that you use to check outlets for things like that.
https://www.gardnerbender.com/en/p/GFI-3501/Ground-Fault-Receptacle-Tester

He wouldn't have 0V hot-to-neutral if the polarity was reversed.

[Tom M King]

The tester will tell you if a receptacle is wired correctly, but it won't tell you that it no longer supplies the next one down the line in the circuit unless you know the order in which the circuit is wired. If it's a bad connection in a back stab neutral, you're still going to have to open some boxes up.

I never heard an answer to the question if anything was plugged into any outlet in that circuit. That will tell us a lot, especially if unplugging whatever that is makes a difference.

[Rich Engelhardt]

That's why I said it "sounds like it might be".
I shy away from most electrical usually.

I do think one of those little testers is a good idea though.

[Bill George]

Rod and Dan are correct a open neutral either in the main box or connection after. If all your wiring is back stabbed and daisy chained I would correct that.

[Bill Howatt]

...

I never heard an answer to the question if anything was plugged into any outlet in that circuit. That will tell us a lot, especially if unplugging whatever that is makes a difference.
This would be good information and if I were to guess, I'd say something is plugged in. This is the only way you can get 120V to ground off the neutral since the 120V has to feed through a device (very, very little current required)to cause a high-impedance voltmeter to read 120V.
I would start at the panel and ensure the neutral was well connected and then hopefully be able to follow the circuit from the panel to the end. You need to leave the whatever is plugged in, plugged in, so you have a voltage on the neutral to measure. As long as you are in the properly connected chain from the panel the neutral to ground voltage should be 0.
OTOH, you could just go through all the receptacles especially if back-stabbed. There is a good chance you will some physical signs on the offending connection such as melted plastic insulation, burned off wire, or very discolored copper wire (or screws if used).

[George Yetka]

I would like my house to be at the studs with no wire so that I can start from scratch and wire it. Even if I was heavily drinking while doing it I can do it better than how it currently is.

Countless wire nuts buried in the walls.
Countless overloaded L&R breakers
Items wired nonsensically. 1st floor dining room, family room, & 1/2 kitchen, outlets and lights in bedroom upstairs and basement water heater on 1- 15 amp breaker
I have 1 GFCI outside that if tripped will make me lose lighting in a pantry closet and the light right outside of it.(nowhere near the outdoor GFCI)
Master bath GFCI will make me lose front side of the house recepticals.
Upstairs wiring has no switch to light or switch to fan home runs they are all pieced together out of 2-4 piece of romex.
When I moved in there was a lamp cord coming out of a light switch cover that I realized when plugged in turns on a light outside.

Ive spent alot of time breaking up circuits and replacing spliced wire.

[Curt Harms]

Well, I found the problem

518840

It looks like back stabbed connections strike again. the fact that the box is in a brick rather than in something combustible is some comfort but I don't know how close to combustion temperatures browned neutral wires indicate. I will either re-wire or replace back stabbed devices as I'm able to gain access. Some outlets are behind large heavy furniture.

Two of the 4 known outlets on this circuit are the ones that have the highest loads, mostly electric lawn mower and occasional portable air compressor. It's a 15 amp circuit - thought it was 20 amp but nope - so it wouldn't be hard to load in excess of 80% of rated amps. The only other significant load I can think of in the house is a laser printer. Those draw quite a bit of power when printing but the load is brief, one or two sheets of paper. The kitchen appliances are all on 20 amp circuits but I don't know how they're wired, back stabbed or not.

[Tom M King]

Glad you found it. I like to use 20 amp receptacles even though code allows 15 amp. Most slightly heavier duty 20 amp receptacles these days have a good connection system that allows straight stripped wires coming into the back. Rather than just relying on a small spring piece of sheet metal to provide the contact, they have a heavier plate that pulls up against the stripped wire end with a machine screw.

I have been known to use an aircraft rivet bucking bar and a hammer to flatten the stripped end of the wire to give it a little more surface area of contact inside that clamp plate.

[Bill Howatt]

80% of the rated amps has little to do with it, you would have the same problem on a 20A circuit with the same type of connections. The problem is the back-stabbed connections got bad and went from close to 0 resistance to some value. The current through this resistance caused heating - the so-called I-squared R heating (watts) and each time the connection heats up it can increase the resistance and cause even more heating. As an example, say your load is 10A and the resistance of the connection increases to just 1/4 ohm this would create 10*10 *0.25=25watts in a very small area (the back-stab) and certainly would cause heating. Another issue depends on the circuit topology, if the outlet you use with the high current loads, like the lawnmower are at the end of the circuit chain, that current has to flow through all the other connections from/to the panel. These receptacles may be showing the effects of heated connections also. Good clean screw connections will solve the problem.

[Doug Garson]

Glad you found it. I'm not an electrician so I'm having trouble understanding how a bad neutral connection leads to a hot neutral. Can any of the Sparkies explain it? I would have thought you would need a short between the hot and neutral to cause the neutral to become hot.

[Tom M King]

It only makes the loose neutral hot when something is plugged into an outlet on that circuit. The connection is made inside whatever is plugged in. The breaker would trip if there was a short, but in this case the loose neutral now can carry the hot load but there is no real short because the now energized neutral is not bonded. Nothing works when plugged in downstream because there is no bonded neutral to complete the circuit. That's why I asked to start with if anything was plugged into that circuit.

I've seen this exact thing twice before on old back stabbed device circuits.

[Dan Friedrichs]

Glad you found it. I'm not an electrician so I'm having trouble understanding how a bad neutral connection leads to a hot neutral. Can any of the Sparkies explain it? I would have thought you would need a short between the hot and neutral to cause the neutral to become hot.

Imagine a load like a heater (which is just a piece of resistive wire) is plugged in, but the neutral connection is broken at the panel. The 120V flows from the hot, through the heater, to the neutral, causing the neutral to have 120V on it.


Glad you found it, Curt. When we bought our last house, one of the first things I did (before moving furniture in) was replace all the old receptacles and light switches with matching, higher-quality versions, and use screw terminals (no backstabs). Only took a few hours and not that much cost.

[Tom M King]

Both of the such circuits that I found like that were in a rental house I bought cheap because it was considered a tear-down for many reasons. It also had one circuit that nothing would work on some outlets unless something was plugged into one receptacle in that circuit. I didn't bother to even think about that one. I just pulled all the devices and replaced every one of them. I think that work was originally done in 1974. Everything works fine now in it.

[Doug Garson]

Tom, Dan, thanks for the responses, makes sense, I wasn't aware that a loose neutral could be that dangerous. As far as I know, none of the outlets or switches in my house are back stabbed, any I've done or looked at are connected using the side screw terminal.

[Tom M King]

I don’t know when they finally went out of favor. I never used them in any of the house I ever built.

[Curt Harms]

I don’t know when they finally went out of favor. I never used them in any of the house I ever built.

I don't know either, maybe after the 10th house fire they caused?:eek: I had previously rewired the appliance receptacles with the heaviest loads - microwave and toaster oven - except for the refrigerator which is very difficult to access the plug.

[Jack Frederick]

I am weak electrically. I learned about proper wiring of receptacles, grounding having to trouble shoot the heating equipment I sold, in this case the Rinnai Energysaver DV wall furnaces. They are extremely reliable and early in the game I took the bait. The unit doesn’t work, it must be the unit and I would get lost testing out every leg off the board. Still intermittent operation. Today’s appliances, the better ones all use flame rectification to prove flame as pilot lights are long gone. Tech services is telling me to check the ground. The ground is testing good. I can’t get 24 hours of good operation out of the unit. Before replacing it I asked the owner if I coulld run it off an extension cord on another circuit. He was a great and very patient guy. We did it and the unit just purred along. I went back, pulled the receptacle and as it came out the hot and ground stayed “stabbed in”. The neutral stayed in the box pointing out at me. Sometimes it would make, sometimes not. Terminated the screw connections on the receptacle and that unit is probably still running 25 yrs later. Stab in connections became a primary discussion in all the contractor trouble-shooting classes I did in the years after.

[Jim Becker]

I don't know either, maybe after the 10th house fire they caused?:eek: I had previously rewired the appliance receptacles with the heaviest loads - microwave and toaster oven - except for the refrigerator which is very difficult to access the plug.
Curious, Curt...about when was your development built? This house here near DelVal went up in 1993 and it's "chock full" of back stabbers and other interesting things.

[Cameron Wood]

I don't know either, maybe after the 10th house fire they caused?:eek: I had previously rewired the appliance receptacles with the heaviest loads - microwave and toaster oven - except for the refrigerator which is very difficult to access the plug.

I have twice traced dead circuits to the refer receptacle- vibration and/or cycling had work hardened the wire at the terminal causing it to break.

[Jim Koepke]

I have twice traced dead circuits to the refer receptacle- vibration and/or cycling had work hardened the wire at the terminal causing it to break.

Wires breaking at termination can also be caused by an inexperience contractor nicking the wire when they strip it with their wire cutters.

It seems there is a lot of controversy concerning backstab receptacles. From what others have mentioned on other sites there can be a lot of failures with them being indicated.

My experience with them is almost nil. Using the screws to secure the wires has always been my choice. After all, the wire stabbed into the back is held in place be spring action. When the wire is shoved into the box, stresses are placed on the wire through bending. Over time there will be heat in the outlet to cause weakening of the spring action. If multiple outlets are daisy chained via the backstabbing, there are too many chances for failure.

That may be why they have fallen out of favor with those in the electrical professions.


I like to use 20 amp receptacles even though code allows 15 amp.

As long as the wiring can support a 20 amp load. A lot of wiring is done with 14 gauge wire that wouldn't be too good with a 20 amp load.

jtk

[Tom M King]

I’ve never used no.14 wire for any receptacle circuit. Don’t remember ever seeing a 15 amp. Receptacle circuit.

[Jim Koepke]

I’ve never used no.14 wire for any receptacle circuit. Don’t remember ever seeing a 15 amp. Receptacle circuit.

It may be something more common in prefab or factory homes. Likely not many of those worth a restoration project.

jtk

[Tom M King]

Even the 1974 house that I bought for a rental, which was considered a tear-down, has 12 ga. wire in the receptacle circuits. That's the one I had trouble with those back stab devices in.

Also, there is some variation in receptacles sold as 20 amp. Some just look like 15 amp devices with the extra slots on the face. Others, maybe sold as HD or industrial are built much heavier. It's the heavier ones I buy. I think the box stores sell both.

[Tom M King]

I've used these needle nose pliers dedicated to one job since the 1970's. I ground the groove so that a twist of the wrist forms a perfect half loop for side wiring. I think every new house I ever built used these. I just went out to the truck and took this picture. The electrical toolbox with drawers sits on the seat behind the drivers seat. These still get used sometimes. I also finally learned to turn the iphone sideways for taking upright pictures for here.

[Cameron Wood]

I have some of those!
518934

[Tom M King]

:DDid you grind that or did it test a hot wire for you?

[Cameron Wood]

:DDid you grind that or did it test a hot wire for you?

One at least half a dozen mishaps over the years- mostly strippers. Still, that's only one every 7 years or so, on average.

[Tom M King]

I have one pair of lineman's pliers that are also good strippers for 10 ga.

[Jim Koepke]

These are my favorite pliers for making a hook to go around a screw or post.

519026

The smaller pair was given to me by my dad. He had them since before I was born.

jtk

[Rollie Meyers]

Glad you found it. I like to use 20 amp receptacles even though code allows 15 amp. Most slightly heavier duty 20 amp receptacles these days have a good connection system that allows straight stripped wires coming into the back. Rather than just relying on a small spring piece of sheet metal to provide the contact, they have a heavier plate that pulls up against the stripped wire end with a machine screw.

I have been known to use an aircraft rivet bucking bar and a hammer to flatten the stripped end of the wire to give it a little more surface area of contact inside that clamp plate.

The innards of a 15A & 20A receptacle of the same grade device is identical, only difference is the face of the device, unless a 20A device is needed and then it would require a dedicated circuit it's wasting money.

[Tom M King]

I know the HD/Industrial ones cost more, but I just like them better and that's not the kind of place I care about saving a few bucks. I expect they're also available in 15 anp, but even though I'd rather have 15 amp faces on the HD devices, I've never seen them anywhere in stock even if they are available. I'm satisfied with the HD/Industrial 20 amp ones. I don't expect anyone to plug in an air conditioner to one of those outlets. I'm only doing my own work.

[Ole Anderson]

The innards of a 15A & 20A receptacle of the same grade device is identical, only difference is the face of the device, unless a 20A device is needed and then it would require a dedicated circuit it's wasting money. Spec grade receptacles aren't that expensive. Here is a common brand with back (not stab) and side wiring for $2.41, the 20 amp version is a buck more. Yea, unless you are using a true 20 amp cord, the 15 amp ones are good to go on 20 amp circuits per code. https://www.amazon.com/dp/B001AXLQKO?linkCode=ssc&tag=onamzdixon414-20&creativeASIN=B001AXLQKO&asc_item-id=amzn1.ideas.14X5KE577KTDL&ref_=aip_sf_list_spv_ofs_mixed_d_asin&th=1

[Jim Becker]

The price difference between 15a and 20a receptacles is minimal in the larger scope of things (I buy the better grade, not the cheap ones) and I prefer that 20 amp circuits have the 20 amp receptacles because it's a visual indicator that the circuit is the higher capacity which is nice in the situations where one might need to use a 20 amp circuit. Now in the house, that would primarily be the kitchen of course. But functionally, it's true that either one is going to "work".