Starting with an effort to diagnose the causes of flickering or dimming lights this series of diagnostic steps by a reader ultimately discover multiple unsafe electrical system features including a bootleg electrical ground, overheated burned electrical wiring and devices, an FPE electrical panel, corroded electrical components, even electricity flow through wet concrete walls!

This article series gives simple diagnostic steps that a homeowner can do to determine the type of electrical system problem that is causing flickering or dimming lights or intermittent loss of electrical power. We list the common causes of these problems and suggest what to do about them.

Flickering Lights: bootleg ground, FPE electrical panel, corrosion = unsafe

Watch out:  flickering or dimming lights often indicates a dangerous condition. Switch off the bad acting appliance or circuit and ask for help from a licensed electrician.

This discussion moves from most-recent down to older comments exchanged by an InspectApedia reader and our editor. The reader reported flickering lights and burned, overheated electrical wiring.

On 2021-03-24 by (mod) - Unsafe wiring: cause & cure of flickering lights, lost neutral, improper electrical wiring, effects of humidity & moisture on electrical safety in a tropical environment home

I understand your points John, and appreciate the additional explanation and description of your building conditions.

I must add, however:

Watch out: improper sources of electrical ground, such as relying on connecting a device ground (receptacle ground) to a metal box whose own connection to earth is uncertain, is very dangerous.

A metal box should itself be bonded to the system ground through a ground wire that ultimately returns to the panel and to earth.

But only for safety.

If the box is normally your ground path (instead of a ground wire) AND worse, where some of your building is "cheating" by connecting neutral wires to the box or to the ground, then whenever anything on that circuit is actually in use, a portion (or in some cases ALL) of the return current is flowing through the metal box to earth by some unknown route.

The result can be a shock or even death to a building occupant.

For example, you plug in a vacuum cleaner and turn it on. The return current is flowing though the metal box, to somewhere to earth, and is not moving through the insulated neutral wire.

The metal box can be touched, and so can bare ground wires or a wet concrete wall or whatever is carrying that current to earth.

Someone touching ANY of those components could be badly shocked.

I have personally seen this happen; it's not just theory. I found improper neutral to ground connections in metal boxes in a building. When I pointed out the safety concern to a home buyer, the home owner, standing nearby, was incensed.

To prove that "There is absolutely nothing wrong with this wiring" he made a fist (I thought he was going to punch me), then he licked the knuckles of his first finger and pinkey of his fist.

He reached up to the overhead metal component that was near a water pipe and touched both at the same time with his wet fist.

There was a short "pffft" sound and the man was shocked and knocked dead unconscious to the floor.

Your reference to the NEC section 250146 (D) may not be the exactly correct interpretation of the code. The code was intended to discuss isolated grounds at receptaacles for noise-reduction on certain electrical circuits.

Watch out: you have described so many electrical defects and hazards at your home that it's quite apparent that your electrical system is quite unsafe, risking a fatal house fire or electrical shock. You need help from an experienced onsite licensed electrician. Our discussion has covered at the very least:

• An FPE Electrical panel: circuit breakers are likely to fail to trip when they should, risking a house fire or shock
• Water leaks and corroded electrical devices and metal boxes
• Bootleg grounding through rusted metal electrical boxes instead of using proper grounding conductor wiring
• Burned, damaged electrical receptacles and probably switches too
• Improper neutral wiring
• False neutral wire connections or connections between neutral and ground conductors

U.S. National Electrical Code NEC 250.146 Connecting Receptacle Grounding Terminal to Box.

An equipment bonding jumper shall be used to connect the grounding terminal of a grounding-type receptacle to a grounded box unless grounded as in 250.146(A) through (D).

The equipment bonding jumper shall be sized in accordance with Table 250.122 based on the rating of the overcurrent device protecting the circuit conductors.

Photo: I'm holding a "heavy-duty" electrical receptacle; you can see the screw-retaining clip at the left end of the receptacle - and there is no paper nor plastic washer retaining the mounting screw: this is to assure metal-to-metal contact between the receptacle's (internally-connected to ground) metal strap and mounting ears and the metal box into which it is being mounted.

[Click to enlarge any image]

Notice at the right end of the receptacle that there is no spring clip but there is a paper washer retaining that screw. That paper washer could interfere with good electrical contact between metal strap and metal box.

In other words, a "self-grounding" receptacle will be designed so that at least one of the device's two mounting connectors do not use an insulating washer.

(A) Surface-Mounted Box.

Where the box is mounted on the surface, direct metal-to-metal contact between the device yoke and the box or a contact yoke or device that complies with 250.146(B) shall be permitted to ground the receptacle to the box.

At least one of the insulating washers shall be removed from receptacles that do not have a contact yoke or device that complies with 250.146(B) to ensure direct metal-to-metal contact.

This provision shall not apply to cover-mounted receptacles unless the box and cover combination are listed as providing satisfactory ground continuity between the box and the receptacle.

A listed exposed work cover shall be permitted to be the grounding and bonding means when

(1) the device is attached to the cover with at least two fasteners that are permanent (such as a rivet) or have a thread locking or screw or nut locking means and

(2) when the cover mounting holes are located on a flat non-raised portion of the cover.

(B) Contact Devices or Yokes.

Contact devices or yokes designed and listed as self-grounding shall be permitted in conjunction with the supporting screws to establish the grounding circuit between the device yoke and flush-type boxes.

About your U.S. NEC citation,

Really? A listed spring-type grounding strap for holding the mounting screw and for establishing the grounding connection of receptacle to box is there so that an equipment bonding jumper is not required is permitted (used only on flush type [metal] box mounting). This is providing a ground for the metal box, it is not IMO intended to provide the grounding path for the electrical circuit nor for the receptacle's ground connector!

The Electrical Contractor in ecmag.com summarizes the intent of this detail:

Section 250.146(D) still requires the receptacle-grounding terminal to be grounded to a separate insulated equipment-grounding run with the circuit conductors.

This separate insulated equipment-grounding conductor is permitted to pass through without any connection to the box. It can also pass through any panelboards without connection to the panelboard with the final termination at the service or at a separately derived system.

This insulated equipment-grounding conductor will carry any ground fault, but the isolated-ground system will interrupt the noise circuit. - 2021/03/24 original source: https://www.ecmag.com/section/codes-standards/isolated-ground-receptacles

On 2021-03-24 by John S. - wants to continue using metal electrical boxes & wet concrete as ground path?

Thanks again, for like the 20th time. I didn't know wet concrete could be an effective conductor - at least not to the point of giving false ground readings. I'll swap out all the rusty outlet boxes, but not for plastic ones right now:

First, since the outlet boxes are presently my only equipment grounding path, I'd lose equipment ground with a plastic outlet box (unless I go down the nipple to connect to the metal jacket of the wiring directly, upstream of the outlet box, which seems to me like it couldn't be an okay thing to do, or up to code).

If I do the whole house rewiring because all the neutral wires going to my outlets are burnt, I could consider it after I put a breaker box in that has a ground bus bar and toss that Stab-Lok in the trash where it belongs.

But, besides that... the reason why flat concrete roofs filter so much water if they're unsealed or the sealing has worn out is because ground settling causes the concrete to warp and crack, producing ponding areas in the roof where there weren't any previously; but perhaps that same movement of the structure may warp or crush a plastic outlet box, and crack it if it is aged, which seems to me more risky than using metal outlet boxes with regular roof maintenance.

I have family in FL and PR, and I've done house maintenance and reconstruction there, and I don't think I'd even consider plastic boxes in Puerto Rico (because it's not just hurricanes that concrete houses have to survive down there, but earthquakes too).

Speaking of grounding code, I've continued to read and realized that grounding through the outlet screws is actually up to code.

Many electricians online have pointed out that it's risky because the yokes can get rusty or painted over in addition to the screws loosening, same as the InspectAPedia page, but

250.146 of the 2020 NEC still says it's okay... for some reason which I can't fathom. At least jumpers and clips will give me redundancy.

Gracias por todo, de nuevo. Adiós.

On 2021-03-24 - by (mod) - wet concrete may carry electrical current

@John S.,

Si - I mean Yes, (aqui hablamos español tambien ) you're probably talking about NMC or non-metallic cable, aka "Romex" or a variety of other names, of which some product versions are specifically labelled for use in damp or wet locations.

Below I include an example, 12/2 UF-B rated electrical wire, rated for wet locations. It's called "UF" or "Underground Feeder" but is rated for use indoors for wet or corrosive locations as well.

For wiring in Miami or other warm wet humid areas, we want to use the best wire, connectors, electrical boxes, and devices we can find that are moisture-resistant.

For me that would include changing out all those rusty metal boxes for plastic ones.

And yes, wet concrete can carry some electrical current.

On 2021-03-24 by John S. - false electrical ground through concrete walls

I found the following on a page:

"With the circuit energized, touch one end of the tester to the hot wire (the smaller slot on the outlet) and one end of the tester to the electrical box. If the tester lights up, the box is grounded. [...]

"If the tester lit up, then all you need to do is run a bare copper wire from the ground screw on the outlet and attach it to the metal box. This will provide a ground using the equipment already in your house.

"If your outlets are installed in a concrete wall, there is a possibility of getting a false reading, but for wood frame structures, this is a good test. If you are dealing with concrete walls, call an electrician to check things out [...]"

Why would concrete walls possibly give a false reading, and what could I or an electrician do to "check things out"?
...

thanks for the ideas. I hadn't even realized that bonding to ground through the metal jacket of wiring was a possibility. Shows my age, or lack thereof: For homes around here, all I've ever seen anyone use within my lifetime is "superservi" cable (and I've never heard it called anything else, because in Miami it's easier to hear Spanish that English on the street, but I'm referring to SOOW cable, whatever it may be referred to commonly in English - romex, maybe?).

In any case, I checked hot against the faceplate screw and got 120 V, so there's grounding of the outlet through the outlet box.

Since the cable feeding the outlet box is encased in the poured concrete, I have no idea what cable it may be, and the internet has been very contradictory in explaining the differences between MC, AC, and BX cable, so I've no idea if the metal jacket I have (whichever it may be) was permitted to be used as grounding.

I guess the only question left is... is it okay to run a jumper from the outlet box to the grounding screw of the outlet? Would this then be a secure way of grounding the outlet and any equipment plugged into it? (I don't even see a hole for a grounding screw in the box; just two nipples.

Can I take the jumper to the outlet from somewhere else, such as wrapping it around the nipple and clamping it securely, or from the outlet ear screws instead?)
...

I continued searching, eventually found the InspectAPedia page

on Electrical Outlet GROUND WIRE CONNECTIONS ,

and ended up answering most of my questions. I'm glad your page has this great resource. I'm going to go get green-insulated wire to make jumpers out of and grounding clips to secure them to the box. (Even if the outlet boxes has screw holes, screwing across the box is not an option - there is only rock-hard concrete on the other side.)

I still wonder about the concrete walls possibly giving false ground readings and what is to be done about that.

On 2021-03-23 - by (mod) - more on bootleg ground through receptacle mount

@John S.,

Check:

So if there is no wire connected to the ground screw on the receptacle, it can still find an unreliable ground connection through its metal mounting ears to a metal box to the box ground or if the box was wired with BX then through the BX exterior (these are NOT safe reliable grounds)

I've also seen electricians hot wire the neutral to the ground screw - a good way to shock somebody.

On 2021-03-23 by John S. - InspectApedia FPE warning + flickering light warning may prevent a house fire

I read up on all the FPE pages on your website. I appreciate how your site has a remarkably complete collection of information regarding these panels and breakers. I’m sure many others are just as appreciative. I applaud your commitment.

The outlet has no connection from ground to the outlet box. I’ll keep researching online and thinking about it. The breaker box has no ground wires going from it to any outlet box, but the neutral that goes from the breaker box to the meter box does connect to a ground wire there; maybe this has something to do with the “grounded” lights being on in all the surge protectors plugged into ungrounded outlets; I don't know yet.

With all the neutrals in the outlets being considerably blackened and no ground wires in the outlets, it seems I ought to begin saving for a full-house rewiring. I’m already doing the regular roof sealings that flat concrete roofs require, so with my adequate maintenance work I expect no further water filtration within walls and no subsequent water damage to the electrical outlets or the concrete-encased rebar of the structure.

It’s interesting how seeking a fix for lights that flickered whenever the washing machine came on managed to slowly uncover all these electrical problems in this house, including all the bootleg grounds and the Stab-Lok breakers and box. Such is life, I guess.

With your help, you may have prevented a fire with property damage and personal injury by using your experience to point the breaker brand to me, even though this was not directly related to the open neutral problem that brought me to this page and to you.

Thumbs up for being a Good Samaritan. I imagine all houses in this block -which were all built at the same time- have this same breaker box; I’ll pass on the word and pay it forward, perhaps multiplying the positive consequences of your willingness to help via your time and your brain.

I’ll go back to waiting for the utility to fix its open neutral as I take care of the other discovered problems as fast as I reasonably can.

On 2021-03-22 - by (mod) - fake electrical ground through receptacle mounting screws & metal box + multiple electrical hazards at this home

@John S.,

Watch out: What you are seeing with your receptacle test that shows it still finds a ground is possibly a fake ground through the receptacle mounting screw connections to a metal box. That is both an unreliable ground and a shock hazard.

Our standard advice is to turn OFF circuits that are producing flickering lights until the whole circuit is examined and repaired or replaced.

Same for FPE breaker-powered circuits.

Bottom line::

there are so many problems it's impossible to have any confidence in any single remote-diagnosis: here are what we've seen (at least most of it) in no particular order:

- wet humid climate causing damage to electrical components

- rust and water entry shorting electrical devices

- overheated wires

- backwired receptacles - unreliable connection

- FPE breakers - unsafe breakers

- DIY wiring

On 2021-03-22 by John S. - bootleg ground connection found at receptacles

@John S., By the way, the outlet with the bootlegged ground I just replaced still lights up the “grounded” light of a surge protector, even though it has no wire connected to ground anymore. I don’t get it.

On 2021-03-22 by John S. - no ground wires to receptacles, neutral wires overheated

thank you for the further education on Federal Pacific.

I understand about the push-in outlets. I’ve always used outlets with screw connectors for the wires. This is the only back-stabbed outlet I’ve seen in this house so far. I guess it was chosen by whomever put it in because of the small (or perhaps crushed) outlet box that reduced clearances for the outlet to basically zero.

So, the house is grounded at the meter box but I have no ground wires going to any outlet and all neutrals look overheated or burnt all over. Is is time for a major refurbishment (with a new breaker box included, of course)? Is there any way to reduce the risk from the FPE box in the meantime?

And I’m still waiting for the utility to fix their open neutral...

On 2021-03-22 - by (mod) - FPE Breakers & Panels are Unsafe & cannot safely be tested

@John S.,

Watch out: you cannot know that an FPE breaker is working correctly by looking at it, not even by testing it, and in fact switching it on and off can increase the probability of a future failure. If you have an FPE panel it should be replaced.

That's not to say that there weren't other electrical problems such as the ones you've shown in the building.

Also as you can read at this website, back wired push and type electrical receptacles are unreliable. If you have a lot of those connections (typically at both receptacles and switches) in your house you can expect more connection failures.

See my article at BACK-WIRED ELECTRICAL DEVICES

On 2021-03-22 by John S.

Thanks for your advice. I know about the infamous reputation of Federal Pacific, but I wouldn’t have recognized their breakers on sight. They do seem to be operating well.

(Nothing blew up when I shorted the circuit by removing the breaker box cover yesterday and touching the frayed hot inside with one of the cover screws, etc., so hooray.)

I removed plenty of insulation (maybe 2”), but it all looks just as burnt further back, on both outlet neutrals I examined.

I also figured on the water damage causing rusting. It’s an eternal problem of tropical houses: habitually made from CMU with rebar, or poured concrete (like this one) because nothing else will resist a Category 5 hurricane, but roofs require plenty of maintenance to avoid leaks through the porous concrete.

I’ve never seen water filtration downwards through a wall go the entire length of the wall to the bottom, though. I’ve been taking care of the house, but it was empty for a long time before I moved in.

I’ll show you another pic where the jumped ground is more clearly evident. I couldn’t snap off the rusted hot and neutral, so I cut them off and left just the jumper.

I already replaced the outlet (and the breakers worked there too, because the hot apparently touched the nipple on the bottom wall of the metal box in my first try at putting the new outlet in. I guess now I know why a push-in outlet was used here but nowhere else in the house - the box is really cramped, for some reason. I wrapped the new outlet in electrical tape and put it in for now.)

On 2021-03-22 - by (mod) - FPE panel and the neutral-to-ground connection are the the worst offenders

@Anonymous, (John),

Watch out: In your photos I see what looks like burned, overheated electrical wiring, badly rust-damaged receptacle and metal box, perhaps water entry and a short circuit?

Watch out: what you also know is a "bootleg ground" we see on that rust-damaged, shorted receptacle that the circuit neutral was also wired through the receptacles ground screw - this is very dangerous and could shock someone badly.

Watch out: I think those are FPE Federal Pacific Electric circuit breakers in one of your photos - if so you should know that those breakers and panels are unsafe, risking fire or shock as breakers fail to trip in response to over-current at a high rate compared with typical properly-performing breakers; FPE panels should be replaced entirely.

See details at: FEDERAL PACIFIC FPE HAZARDS where you'll also find links to FPE Identification photos & tips.

About re-wiring the whole house: not based on that one photo of an overheated neutral wire tip; inspect the wire insulation; if it looks burned or discolored AND if there's not enough extra length to cut back all of the suspect wire, then yeah you may need to add a junction box and new wire fed into the new receptacle and box from a point at which the wiring is intact.

Electrical Wires don't "wear out" from use, but they can be damaged from overheating, mechanical damage, even rodents or water.

From what I see in your latest photos the FPE panel and the neutral-to-ground connection are the the worst offenders, though that terrible rusting of the electrical system components also risks fire and shock.

On 2021-03-22 by John S - burned electrical receptacle wires & FPE circuit breakers & panel = unsafe

On 2021-03-22 by John S. - circuit breaker box cover screw penetrates wire + Bootleg Ground Wire

hi again. If the system lets me, I’m going to add an image to this post (or as replies to it) that you can use as examples and cautionary tales for your readers.

I asked someone else for advice on my suspected lost neutral and I got told to check my breaker box.

I hadn’t touched it until now, because I had noticed the different voltages at different parts of the house by measuring the outlets with a multimeter; and then I proceeded to check the connections inside the meter box to see whether the suspected open neutral was upstream or downstream of the meter; so I had no apparent reason to mess with the breaker box.

The breaker box dates from 1964/65.

It has no main breaker and just six breakers: total: Four are singles for 120 V service, which cut power to a different quarter of the house each, and two are doubles for 240 V service, one of which is connected to the electric kitchen range, and the other one of which is used at 120 V with one hot and one neutral for the water heater.

I actually tripped three of the breakers while removing the cover.

As it turns out, the breaker box cover screw that I’d left for last had frayed the insulation on a hot wire the last time it was screwed in, apparently, and a minimal movement of that screw made contact with the exposed part of the hot wire as I pulled the breaker box cover away.

In any case, I got my second big surprise soon enough: From the wiring of the breaker box, it seems that absolutely none of the outlets in the house are grounded. This is a surprise for two reasons:

First, all the outlets in the house are three-prong; and second, all the surge protectors with a “grounded” light have that light turn on when the surge protector is plugged in. There appears to be only one ground wire inside the breaker box: Insulated in white instead of green, it comes from the kitchen range.

All other wires connected to the neutral busbar of the breaker box appear to be bona fide neutral wires.

I checked some outlets by unscrewing them and checking their wiring. The first had only two wires connected to it: a hot (insulated in green!) and a neutral, but a surge protector plugged into it still showed grounding.

The second was even more of a gut-punch: a completely rusted-over (but still live!) outlet with a jumped ground to neutral. I’ll send you a picture for your free use in your future educational efforts.

The bootleg ground I understand, but the “grounded” light on the other two-wire outlet is more confusing. I assume it is in series with another bootleg ground somewhere, but I’d need to check all outlets to confirm.

I wonder whether the supposed ground that is lighting up the surge protectors is instead a reflection that the house *is* grounded, because the neutral that goes from the breaker box to the meter box is connected to the wire that goes from the meter box to the grounding rod (and also to the neutral wire that goes from the weather head to the meter box, and also to the back of the meter box itself at this same spot too).

Perhaps you can set me straight on this.

I also assume I can’t change the breakers on this old box to GFCI without changing the entire box. The costs may be comparable to running green ground wires from the old box to every outlet. Perhaps you can set me straight on this as well.

But, speaking of rewiring, the two outlets I disconnected had neutrals that looked more black than copper. Should I (or, at this point, do I need to) rewire the neutrals in the entire house?

Thanks. Again. And again. And... again.

On 2021-03-21 by (mod) . - neutral or ground touching the side of the box - may be unsafe

The neutral wire, ground wires, and metal electrical box are properly tied together only in a main electrical panel where there will be at least one, better two grounding conductors to earth.

Watch out: But when neutral wires are connected to the building grounding system anywhere else in the electrical system there is risk of occupants getting shocked.

That's because the grounding conductors are not intended to normally carry current. Making ground "live" by passing along the neutral wire's return current through ground means that someone could be shocked.

I saw this happen in a wet basement when an irate homeowner, expressing his disagreement withy my opinion and warning, licked his knuckles and touched his hand between an electrically-live metal pipe and ground.

He was shocked enough to get knocked right to the floor!

On 2021-03-21 by John S. - so neutral or ground touching the side of the box can’t be a bad thing ? Really?

thanks again. I really am appreciative of your experience, wisdom, and willingness to help.

I’ve tried looking around and it seems like the box is bent in near the neutral point and is touching it; yet I can’t see the significance of this, because the metal clip and screws bonding the neutral and ground are attached to the rear of the metal box anyway, obviously by design, so neutral or ground touching the side of the box can’t be a bad thing.

I figure measuring the lines against the box ought to be the same as measuring against the neutral point, so maybe I ought not be surprised if I get a non-zero voltage. I’ll take your word that I’m not supposed to get any voltage measuring the metal box against the lines, even if I’m not sure why.

Anyway the ~20 V gap between the lines with a load reeks of lost neutral outside, so it’s just a matter of waiting for the utility. It’s been well over a month now, and no service is in sight anytime soon. Enjoy your day.

On 2021-03-21 - by (mod) -

@John S.,

good detective work, and good going not to get shocked or killed.

If I've understood you correctly, indeed one should never see voltage between the metal box and ground as the box should never be "live" - if you find that, as you report, I agree that there is a short, hot to ground or hot to neutral, somewhere.

And of course as the metal box is grounded one would expect to be able to measure voltage between a hot wire and the box or a hot wire and ground.

In the electrical main panel (and not further into the building) the ground and neutral buses are ultimately made common. What I found in some of our "lost neutral" articles in this series was that when the utility company's neutral failed, we were relying on our local ground for all of the return current that normally flows on the neutral wire. A result can be overheated and even burned ground wires.

FLICKERING LIGHTS, LOST NEUTRAL

and

LOST NEUTRAL SHOCKS HOMEOWNER

are worth a look

On 2021-03-21 by John S. - update on lost neutral at electric meter

I mis-spoke in my previous message; it’s the neutral that goes down the same hole as the two lines and the ground goes through its own hole. I’ve added a couple of pictures of the billing meter area; measuring the lines against the sides of the metal box gives me the same readings than measuring the lines against the neutral point.

I’ve thought some more and I now assume the entire box is grounded for safety so I ought to get these measurements, and the spots where I just get zero probably have to do with eddy currents across the metal surface or something.

Either way, the lost neutral is not due to anything within the house; it’s upstream from the billing meter.

@danjoefriedman Hello. I know I said I wouldn’t bother you again, but I’m writing to give you an update more than I am to ask for further advice.

I managed to do what the less-than-fully-competent electrician sent by the homeowners’ warranty service refused to do, which was measure around the billing meter. I couldn’t ask him to do more than he wanted on his visit because I wasn’t paying him for his visit (the warranty service was), but I read up a bit, went to the billing meter, and opened the panel immediately below.

I saw the two live lines descending from the billing meter; next to them, I saw the neutral descending from the top of the box and, further down, saw the point of union with the ground wire. The ground and both lives went through a hole at the bottom of the box, while the neutral continued down and went through its own opening.

Across the live lines, I measured 243 V, and each line measured against the neutral point with ground gave me 122 V with no large load inside the house; just as it should be.

When I turned on the vacuum cleaner (or a hair blower, or the water pump, or the washing machine, etc.) I repeated the measurement and got the same ~130/110 V line split that I saw in the outlets inside the house with the same 243 V total across the lines. This gave me extra confidence I have an open neutral that is outside the house. But...

On a whim, I decided to measure the lines against the metal inside walls of the box rather than against the neutral point. Depending on where I measured, I got either 0 V or the same 122 V difference that I got against the neutral point.

So now I’m thinking there’s a short in the billing meter area somewhere. I’ll keep exploring. Enjoy your day.

On 2021-03-17 by John S.

thank you (again). This is house dates from 1964-65. From what you say plus what I see, I’m fairly sure the grounding electrode is inaccessible. There’s likely a tube embedded within the cement wall that would carry the wire that would connect to the grounding rod.

The electrician that inspected the house and refused to deal with the service meter told me that even though his instructors were to tell the power company that everything inside there was all right, that they’d be able to see that he hadn’t looked because that required breaking some seals inside. Given that, I think I’ll pass on measuring the ground wire connection at the billing meter panel and just wait until the power company shows up (or until Hell freezes over, which will probably happen first).

I won’t bother you again. Thank you, and goodbye.

On 2021-03-17 - by (mod) -

@John S., I hope you will let us know what the power company technician tells you as that will certainly help other readers. Thanks.

On 2021-03-17 by John S.

thank you (again). This house dates from 1964-65. From what you say plus what I see, I’m fairly sure the grounding electrode is inaccessible. There’s likely a tube embedded within the cement wall that would carry the wire that would connect to the grounding rod.

The electrician that inspected the house and refused to deal with the service meter told me that even though his instructors were to tell the power company that everything inside there was all right, that they’d be able to see that he hadn’t looked because that required breaking some seals inside.

Given that, I think I’ll pass on measuring the ground wire connection at the billing meter panel and just wait until the power company shows up (or until Hell freezes over, which will probably happen first).

I won’t bother you again. Thank you, and goodbye.

On 2021-03-16 by (mod) - electrical circuit load may affect voltage level & flickering

@John S.,

The building will, if it's code compliant, have at least one, probably (on newer buildings) two connections to earth: a grounding electrode or on older buildings sometimes a connection to the water pipe or incoming water main. If your electrician were looking for the grounding system components she'd follow the electrical grounding conductor out of the panel.

I am not an authority on all of the various sources and causes of voltage variation;

Among the myriad of causes, obstructions to or damage to or inadequate wiring are cited in some sources, more likely to be observed when the wiring is under load.

In your case, however, more likely the underlying cause is resistance at or otherwise poor connections at the neutral leg of your circuits - and from your description, at a power-company connector at the meter or ahead of it.

The underlying principle is that an increase in current flow in a circuit causes a voltage drop across the resistance of that circuit. If I've got this right, when you are measuring voltage level on a receptacle circuit with nothing plugged in and then add a load such as your vacuum cleaner, if there's abnormal resistance in the circuit you might indeed see a voltage drop.

See details at OHM's LAW, ELECRICAL RESISTANCE

On 2021-03-16 by John S.

@danjoefriedman

Never mind; I tested an ordinary outlet and hot-neutral gave me 119.4 V, while either hot or neutral with ground gave me the same 119.4 V and exactly 0.00 V. I turned on the vacuum cleaner; I got 129.0 V on hot-neutral, and measuring both against ground gave me the same 129.0 V and exactly 0.00 V.

There does not seem to be current flowing through ground. The suspected bad utility neutral isn’t bad enough apparently to cause current to flow to ground.

I’m still confused by how turning on a vacuum cleaner (or any other motor, like the washing machine) can cause voltage to go up in part of the house (especially since voltage goes down in another part of the house at the same time.)

On 2021-03-16 - by (mod) -

@John S.,

The building will, if it's code compliant, have at least one, probably (on newer buildings) two connections to earth: a grounding electrode or on older buildings sometimes a connection to the water pipe or incoming water main. If your electrician were looking for the grounding system components she'd follow the electrical grounding conductor out of the panel.

Working backwards starting at the grounding electrode, the electrician is measuring to try to find where the current is or where neutral has been lost

Watch out, and if you're not familiar with safe electrical wiring and testing you could be shocked or killed

On 2021-03-16 by John S.

Where do you suggest the best place to measure current to ground is, if I’m going to do it myself? In the breaker box, inside the billing meter panel, somewhere else..?

I have no idea how to find the grounding electrode. The service meter is in the southwest corner of the house and all wires running from the billing meter run along the inside of the wall, which is poured concrete. The breaker panel is in the north wall of the house, on the other side from the billing meter, and all wiring from and to it also goes through the inside of the wall, which is also poured concrete.

On 2021-03-15 - by (mod) -

@John S., my best guesses, more complete than making it up again off-the-cuff here, are in the article above.

Watch out: if the utility company's neutral connection is poor - (that might be anywhere in the panel or meter or outside near your home) - your electrical system may be relying on your local ground connection to earth at your home to run your electrical system at all. If that's the case it's very dangerous with a high risk of electric shock .

An electrician who knows how to use a DMM or VOM (or you as you've got a multimeter) would check for unexepected current on the ground- system.

On 2021-03-15 by John S. - flickering lights traced to bad utility company neutral

Hello. I have an issue at my house that is similar to the "Flickering lights traced to bad utility company neutral wire" story by Phil that's above on this page, but not identical to it.

The "grounded" light on my surge protector also flickers with the cadence of the washing machine, as did Phil's lights. But, beyond that, when any device with a large-enough motor is running (i.e., vacuum cleaner, water pump, etc.), my appliance surge protectors show an over-voltage situation in one part of the house and an under-voltage situation in another part of the house, simultaneously.

In the over-voltage part of the house, my multimeter shows ~130 V (normal is ~120 V), but I suspect that this is because of the averaging time of the meter, since the surge protector light isn't supposed to turn on until there is a peak of more than 140 V detected. Similarly, in the under-voltage part of the house, the multimeter shows ~110 V but the surge protector under-voltage light is meant for cases of less than 90 V. Therefore, I suspect there is a great amplitude of the voltage oscillation within an AC cycle, with the voltage peaks and valleys going beyond the surge protector limits very briefly.

An electrician came by and told mehe thinks the fault lies with the power company neutral wire, since the connection from the power pole outside the house shows visible signs of corrosion. However, there is no expectation for the utility to respond rapidly due to an ongoing labor dispute (i.e., employee strike).

I assembled makeshift extension cables from 1 ft lengths of 10/3 SOOW wire meant to serve as buffers between the wall taps and the appliance plugs, so that the large gauge would moderate the voltage irregularities and prevent more damage. (The water pump's computerized control was fried a while back, and the repairman blamed the electrical problems in the house.) This, of course, is a work-around and not a work-through of the problem.

I'm not too confident in the competency of the electrician that inspected my house, in part because he refused to look at the panel where the utility's billing meter is (because he was in a hurry) and told me to tell the power company that everything inside there was all right. So, I have two questions:

1) Do you have another possible idea as to what could be causing the problems, besides the corroded utility neutral connection?; and 2), do you have any other suggestions for me as to what I could do to normalize the voltage in my place until the power company shows up, besides the 10/3 SOOW buffer extensions that I'm currently using?

Thank you in advance.

 

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