I moved in to a newly renovated Victorian house here in England in December, which we bought from a property developer.
It was completely rewired, with everything signed off and certified by a qualified electrician, as per legal requirements.
Most properties in the UK have common earth/ground and neutral wiring (they're the same wire, the "earth" just bypasses your main board... there's no earth spike).
Anyway, I bought a socket tester after noticing an outlet or two didn't work. Went around and tested the whole house... half of the 30 electrical outlets in the house were defective, and at least 4 were wired incorrectly such that they were live on the neutral pin (which means they're live when the switch is off). Some had earthing issues. Fortunately the RCBO's work as advertised.
Don't risk your life with this stuff, test it all yourself. A tester will cost you $10
For anyone else confused by this - it's a British thing. In America, all outlets are live all the time. British outlets have a switch per-outlet, built in.
This would affect switched outlets in the US, too. When we install light switches in the US, we usually only use a single pole switch that breaks hot, not neutral.
But yeah, British outlets do have switches directly on them. And fuses in all their plugs—awesome stuff.
The old ring circuit wiring in the UK did not adequately protect the wires in the walls against thermal overload. If you drew too much current from a single outlet, you could overheat the wires without blowing a fuse or tripping a breaker. So fuses were added to the plugs, since rewiring was impractical and reducing the house’s fuse or breaker rating would be annoying.
In the US and elsewhere, equivalent protection comes from correctly sized breakers in the panel.
Ring circuits are terrible, but fused plugs are not.
> In the US and elsewhere, equivalent protection comes from correctly sized breakers in the panel.
That’s a common misconception. Your circuit breakers are rated to protect the wires in your wall—nothing else. The wires you plug into your wall receptacles are rarely rated to handle full capacity of that circuit breaker and can be overloaded without tripping that breaker.
A common example of this is an extension cord that breaks off into multiple receptacles on the end. Depending on the quality of the cable, you might be able to draw 20A through that cable and start a fire without ever tripping your breaker.
If each plug is fitted with a fuse that matches the rest of the cable, this issue is largely mitigated. That’s why Christmas lights often have fuses in the plugs: those cables aren’t able to handle the maximum load that your circuit breaker and in-wall wiring can tolerate.
The necessity of using a fused plug to protect the in-wall wiring in a ring circuit is (IMO) terrible.
The NEC does have restrictions on the size of a breaker supplying different types of receptacles. 20 amps through, say, a 18AWG extension cord shouldn’t be that dangerous as long as the cord uses high temperature insulation. But your point is good: a fuse protecting the cord would be a very sensible feature. (Even better would be ground and/or arc fault protection in the cord, but that gets expensive.)
That is really something to be reported to the relevant authorities because it indicates that this "qualified electrician" did not know what he was doing and did not perform tests...
I do DIY electric work (as much as permitted) here in the UK and I always use a socket tester to check correct wiring and Earth connection. That's a no brainer.
Side comment: that's why I am always wary of properties refurbished with the aim of reselling them, or properties where the owner "has just <built extension | converted loft | etc>".
I've seen houses with ground bonded to the copper water/gas pipes...and upon further inspection they were supplied with plastic piping outside of their property boundary. Yikes.
My understanding is that neutral goes to ground at the substation
They are bonded to ground so that if a hot happens to run or chaff up against them, you don't have hot water or gas lines conducting in your house -- a dead short to ground will trigger a breaker overload (near) immediately assuming they are working correctly.
If these pipes were not grounded, they are just pretty scary conductive pieces of metal strewn throughout walls and ceilings, and usually terminating at a place where people physically contact, as well.
> My understanding is that neutral goes to ground at the substation
Close. It's at the transformer.
North American "split phase" power has the neutral center tapped into the transformer winding. The two 120v lines are phased 180° from each other with respect to neutral. Line to line gets you 240v, line to neutral is half that, 120v.
Downstream in the breaker panel itself, the grounding conductor (ground) and grounded conductor (neutral) are bonded at the panel. The ground wire is basically just an alternate path back to the box.
That's not acceptable, and I would consider complaining to the trade body of whichever electrician provided the EICR for the property. NICEIC and the like regularly check the standards of work of their members, and it sounds like this one needs some special attention.
It's great that we have RCBOs and RCDs everywhere these days, but BS7671 still has a requirement for "good workmanship by skilled (electrically) or instructed (electrically) persons".
There is definitely supposed to be an earth spike, or something equivalent such as bonding to a metal pipe that extends underground.
Earth is supposed be be a separate wire because it's not supposed to carry current- current on earth detects that something is wrong. The neutral wire carries an equal and opposite current to live. (what we call neutral is not exactly the same as the neutral on a split phase system like in the US)
> something equivalent such as bonding to a metal pipe that extends underground.
I discovered recently that this is advised against, at least in my country, nowadays since metal water pipes are being replaced with plastic ones. But sometimes not up into the house. So it might look you have a metal water pipe running in the ground. But it cuts off to plastic just outside your house. And it might not be buried deep enough to act as a proper ground. So always test with proper equipment what your earth ground resistance is and don’t assume anything.
> I even checked my electricity 'pen' reader on an HDMI at work to see if it was the reader. It's not the pen. It's my wires.
Ah… there it is. Stop using those; use an actual multimeter.
See, the problem with measuring voltage is that you really need two points of reference: you’re really measuring the voltage potential between two separate points.
When you say your HDMI is live, what does that mean? Relative to what? Are you talking about the grounded shielding, or one of other conductors?
This individual is waving around a no-contact A/C voltage detector. These can be useful indicators in the right hands, but they’re just estimation devices. They’re prone to false positives and negatives.
If you wave one near an HDMI or coax cable, there’s a good chance it’s going to beep and turn red.
That being said, if you see your lights getting brighter on the regular (rather than dimmer), your neutral is probably going bad, and that can be quite dangerous. Call your electric company and/or an electrician if you see that. It’s not going to stop your coax and HDMI from showing as live when you wave a death stick near it, though; they are live, at least from the perspective of a no-contact voltage tester.
This sort of problem is a big moneymaker for electricians.
They look at it and say "yeah, it's fucked. You need a full rewire, $20k".
When the reality is that with a bit of measurement and testing you can find the missing or broken neutral or incorrect grounding, and fix it for a couple of hours work.
Nearly all electrical fires are caused by newly modified electricals anyway, so 'just rewire it all' is probably making your property less safe rather than more safe, at least in the short term.
Anecdotally, as a firefighter for almost 20 years, the ones in my area have been overloading of old wiring, or stupidity. (Jamming a breaker open, etc.)
I wonder where you live if one can jam a breaker...
All the breakers round me have a mechanism so you cannot hold them 'on'. Sure, the bit in your hand will be pointing towards on, but the electrical switch internally trips and flips to off.
You already nailed it. Use the three prong plug. If you don’t, stray voltages can occur on the metal casing of your device. I also learned that some usb-c cables connect ground to your device (via the charger) and some don‘t. It‘s not as universal as it is marketed.
I’ve been annoyed for the longest time that Apple in North America only sticks grounded plugs on their 1m+ power cables. Very inconvenient for travel. I don’t want to bring an extra 1m cable in my carry-on. I want the little two-prong “duck head” adapter—just with three prongs.
No, that's a different (and often "officially allowed") thing. I believe it has to do with stray capacitance. A lot of 2-prong devices are doubly insulated (the symbol on the charger is 2 concentric squares). Weirdly though I have noticed that "tingly" feel even with my 3-pronged laptop charger.
> US electricity rules are something out of a 3rd world country
If you read about the CEE 7 standard that aims to unify power plugs and sockets in European countries [1], which includes the "Europlug" [2] mentioned in a sibling comment, you'll see that the situation is not any better than in the US.
For example, about the CEE 7/7 plug which bridges the difference between socket types in Germany (2-pronged - also in Denmark, Spain, etc.) and France (3-pronged - also in Belgium, Czechia, Poland), it mentions:
> This plug can be inserted into a Danish Type K socket, but earthing is not enabled.
The issue they are talking about can (but shouldn't) also happen with the "Europlug" which is also used in Denmark: https://en.wikipedia.org/wiki/Europlug
I assuming that you’re taking what I wrote as US electricity rules but the devices/rules I mentioned were for European products. My iPad that gives me a slight tingle was purchased from the Apple store in The Hague so it’s EU compliant. (I’m Indian and I believe India too has similar rules. Double insulation is generally pretty safe, if a little annoying.)
Even in the UK, which has quite stringent electric regulations, you can get two-conductor cables with a plastic earth pin (which is always required even if you don't need grounding as otherwise the shutters covering the live and neutral holes are not withdrawn). On the other end, it could have a "figure-of-8" IEC connector.
And I definitely noticed a tingle on some metal laptops even when they have a 3-pin plug and a "Mickey mouse" IEC connector on the cable to the power brick.
Are you talking about the bumpy feeling when moving your hand along the chassis? I get that on a metal-body Dell sometimes too. And it doesn't seem to happen if I press hard while moving my hand.
I would assume that's because you're increasing the contact area and therefore more of your nerve endings are getting a lower voltage, pushing it below the detectable range.
Wait until you're using it on your chest in bed and accidentally poke your lips with the corner! It's a surprisingly good zap for an allowed amount of stray
Fascinating, I never knew this is how it worked. I feel like I've run into this before at friends or family's houses and shrugged it off as bad house wiring or the like.
No it wouldn't. The neutral was cut, that tool can't reliably identify that problem. The tester will see a voltage that depends on the other loads in the house, which might be lower or higher than normal.
Your tester would also still show the outlet as grounded, because it just checks for continuity from neutral to ground at the outlet, which exists even when the utility neutral is broken because of the neutral-ground bond at the service entrance.
A common misconception is that the neutral-ground bond at the service entrance is what makes the system grounded. That is not true: it is the neutral-ground bond at the transformer that makes the system grounded. If you break the utility neutral wire, the ground (earth) is too bad a conductor to work in its place, even if the transformer and panel both have intact neutral-ground bonds.
> A common misconception is that the neutral-ground bond at the service entrance is what makes the system grounded. That is not true: it is the neutral-ground bond at the transformer that makes the system grounded
Er, what? It's any/all of the neutral-ground bonds that make the system grounded. The more ground connections, the more redundancy and lower impedance.
... which is probably why the plumber didn't worry too much about disrupting the building's ground connection. If everything else is wired up right it's not going to be that big of a deal - perhaps a few volts on the building's grounding conductor versus actual earth, due to the current on the service neutral.
> Er, what? It's any/all of the neutral-ground bonds that make the system grounded.
The misconception is that cutting the neutral-ground bond at the service entrance makes the system ungrounded, which isn't true. You can cut that, and nothing will change under normal operating conditions.
> The more ground connections, the more redundancy and lower impedance
That isn't true in the US. The only permitted neutral-ground bond in a house is at the service entrance.
In the US, if everything else is wired correctly but you disconnect the neutral-ground bond, you may end up with rather high ground impedance. Those two ground rods, 6 feet apart, that satisfy code could easily have quite a few ohms in dry weather. This, in turn, could allow a live (120V to ground) wire to short to an equipment ground, drawing only a few amps and making every grounded object in your house quite dangerous indefinitely.
Since the NEC does not require any form of residual current detection except for some branch circuits unless you have a huge service, nothing really protects against this type of failure.
Yeah. Here in EU I get 3 phase cables only coming from the transformer. Then at my house a grounding rod is used to give combined Protective Earth and Neutral (TN-C). At my house main panel they are split into PE and N (TN-S). They are never connected house side and I now have combo RCD’s so each automatic fuse is also an RCD.
EDIT: I was wrong, there are 4 conductors coming from the transformer, 3 phases and a Neutral. Phase-Neutral 230V and Phase-Phase 400V.
Grounding rod connects to the Neutral and 4 conductors come to the main electricity cabinet. There Neutral and PE are split.
Residential US electricity primarily uses center-tapped single phase transformers, with 240V between the two ends of the coil, and 120V from either end to the middle. The center tap is grounded and treated as a neutral for 120V loads from either "hot", and 240V loads run between the two "hots".
The advantage is that we get 240V power with 120V shocks (assuming you grab a hot wire while you are grounded). The disadvantage is exactly what the original post was about: if the neutral wire breaks, it can fry everything in your house, because your toaster is now in series with your lightbulbs between the hots.
It sounds like the branch circuits must be wired delta (phase to phase, rather than phase to neutral). What's the neutral actually do? Or does your earth have low enough impedance that you can get away with low power loads returning unbalanced phase current through the earth?
That's odd, and I can only think you must live in an area where the earth is conductive enough to carry significant current (or are the cables coming from the transformer inside a metal conduit?)
The earth is nothing like "an endless source/sink for electrons". Rather, electricity always flows in a complete loop (circuit), and the current flow is somehow getting back to the transformer to complete that circuit.
> The earth is nothing like "an endless source/sink for electrons"
It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it. You can think of the earth as a constantly-recharging (but sometimes rapidly discharged) anti-supercapacitor. Just like the atmosphere is a constantly recharging (but sometimes rapidly discharged) regular supercapacitor.
Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground. It’s not just your local neighbourhood transformer; if your transformer’s resistivity increased too much due to the added ground-return current, then the rest of the current could find another path to some other, further-afield transformer, or multiple such. Or maybe even the local power plant. Or some unrelated grid-connected power plant. Or—dangerously—a power plant connected to a physically proximate but electrically disconnected grid… which is in part what makes power-factor wobble around so much in black-start grid power stations.
> It’s a bounded sink for electrons, though — i.e. it has capacitance — insofar as a positive ionization required for a static discharge (lightning) built up in the earth can be “spent” by grounding voltage into it.
The Earth has no special ability to absorb electrons beyond what a jar of dirt does.
In a lightning discharge, the earth and the thundercloud act as opposite plates of a capacitor with an air dielectric.
As a thought experiment: if I built a hypothetically perfect giant metal shield covering the entire planet 100ft above ground, and perfectly insulated it from earth, lightning would discharge to the shield, and there would be zero potential from the shield to the actual Earth either before or after the discharge. There is nothing electrically special about the physical Earth, it's just a conductor.
> Ignoring that, though, what people usually mean by this is that the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground.
What you're describing only happens during fault conditions.
Except in extremely unusual circumstances like [1], the Earth is not used as a normal return path for utility neutral current. The return current flows on dedicated neutral conductors. Actually, in am ideally balanced Wye, there isn't any real neutral current at all.
Sure, the earth in bulk is essentially a conductor and it's possible to transmit electricity through the ground (eg single wire earth return). I would just think it impractical for last hop residential distribution (eg the effect in the original post), as getting a good connection is hard and the distance is short.
> the combined neutrals of the entire power grid are on the other end of any dumping of current you’re doing into ground
This only makes sense if the primary side of the transformers have a grounded conductor ("neutral"), and it's bonded to the grounded conductor on the secondary side. I don't know much about common power distribution topologies, but this would seem less safe as it would increase the possibility of the high distribution voltage trying to find its way back to the plant/grid/ground through end-user services.
I would be happy to be proven wrong... but I bet your transformer has a grounded neutral point with a dedicated conductor to your service panel, even if all your loads are phase to phase.
It could be corner grounded... but my understanding is that is very uncommon.
EDIT: I read your post again and I think "three phase" means "three wires": a 240V hot, a 0V neutral, and an earth wire?
Yeah. I thought maybe the author of that post was confusing "three wires" with "three phases".
I don't know about the EU, but in the US there's almost always a grounded neutral point on three phase systems, even if the loads are all phase to phase. All the literature I've ever found says corner grounded deltas are "not to be used in new installations", and ungrounded deltas are similarly discouraged.
They also make the electrical-wiring equivalent of a cable toner, which is something I've wondered about for ages. Having recently bought a house wired by an electrician who did fine work in the conduits but seems to have struggled with the command of written language required to produce legible labels in the panel, I expect to get good use out of the one I've just ordered.
(The outlet tester/tone generator in this kit doesn't show voltage, but multimeters are cheap these days and much more generally useful.)
You would see fluctuating voltage depending on load. Normally you should only see local load variations of maybe a volt or three (unless you're doing something with long extension cords and like living a bit dangerously). A loose/lost neutral situation can see voltage fluctuate 10s of volts. I think technically the range would be from 60V->180V, but, don't quote me on that and I'm not sure this meter can see that wide of a range.
Yeah and that number (voltage on one leg) would increase well above 120V when you place a large load on the other leg using other devices like space heaters.
It was completely rewired, with everything signed off and certified by a qualified electrician, as per legal requirements.
Most properties in the UK have common earth/ground and neutral wiring (they're the same wire, the "earth" just bypasses your main board... there's no earth spike).
Anyway, I bought a socket tester after noticing an outlet or two didn't work. Went around and tested the whole house... half of the 30 electrical outlets in the house were defective, and at least 4 were wired incorrectly such that they were live on the neutral pin (which means they're live when the switch is off). Some had earthing issues. Fortunately the RCBO's work as advertised.
Don't risk your life with this stuff, test it all yourself. A tester will cost you $10