Came back from the pub quiz last night to find the downstairs in darkness.
The RCD had tripped. It would not reset unless we had all the light switches off.
The lights are on a 6A RCBO with an 80A 30mA RCD
Strangely though we found out that I can have a small number of lights on, but beyond that point, the RCD or RCBO goes. It doesn't like fluorescents, they will trip every time, yet 5 incandescents on a dimmer in the front room are OK. Although some of the lights that will stay on are are energy savers (so fluorescents!)
The Megger shows live earth and live neutral OK! (With all light switches turned off - so is it a fitting?)
That suggests that some of your light switches are switching the neutral? or is that you have a neutral earth leak that is insufficient to trigger the trip as well as some other leakage path which is switched in by some of your lights. Have you got enough real lamps to use for now in place of the crap CFLs. Might buy you some peace and quiet over the festering season!!
An interesting one, not least for the totally illogical way that the previous owner had wired it! (He was a builder, so I should have expected it I suppose!)
I live in an 1890s terrace. From front to back we have 2 lights in the hall, one in the living room, two in the dining room, one in the kitchen, one in the utility room one in the cloakroom and one outside.
With the Megger I quickly established that the back of the house (from the kitchen was OK). I had to get most of the upstairs bathroom and landing floors up to work out the feed from the fusebox goes to the living room first (5 incandescents on a dimmer and worked fine) then to the dining room (one three arm fitting that only worked with one energy saver fitted) a double fitting that tripped with anything in) then splits back to the hall and forward to the kitchen etc.
To cut a long story short and after about 4 hours of testing (removing wires, Meggering etc.) it turned out to be an overheated chocolate block (poor connection?) in the three arm fitting in the dining room that was shorting earth/neutral (yes the one that was working!) and once that repaired, all was OK)
What a sod to find though, not helped by the fact it "seemed" OK!
Anyway all sorted and a Happy Christmas to all on UK DIY
I'm in the US and it sounds like you're in the UK or some other European country so I know our wiring is different, but ... maybe you can clarify my confusion in this post; always interested in things different from my own situation.
I fail to see how a neutral/earth short could cause any visible problems. Depending on resistances back to the electrical panel, they should simply share the neutral current, or if the resistances are different, the lowest resistance path would carry the current back to the panel. Normally Earth leads should carry zero current.
I suspect my confusion is due to things like "The lights are on a 6A RCBO with an 80A 30mA RCD", which are absolutely meaningless to this yank! So apparently the key words you're using are not ckt breakers, but some other form of protection that relies on other than simple current overloads; right?
Hmm, I may have worked it out. Google was no help with its gazillion hits of Roman Catholic ... , but Wikipedia seems to have filled in the blanks! And here I thought I understood your ring ckts and all that! lol.
I know for instance that RCBO = Residual Current Circuit Breaker with Overcurrent Protection. THAT sounds like a ckt breaker but Residual Current fits in there how?
Wikipedia seems to indicate that RCD stands for "Residual Current Circuit Breaker "; is that right? Now that sounds like what we might call a GFCI or Ground Fault Ckt Interruptor, a product that keeps a measure of the current in the hot and neutral lines and if they vary by more than a few milliamps, opens the ckt., assuming there is a fault at some point. Would RCBO be the same thing, the only difference between the two being that one is located at the point of use, and the other at the Mains electrical panel?
Thanks for any clarification anyone is willing to provide,
RCD's, or Residual Current Devices (fomerly known as earth leakage circuit breakers,) are very common in 240V areas. Remember much of your electrical supply is 110V - sometimes even
55-0-55 - with 240V across phases used for higher power equipment. In Europe we use a (nominal) 230V single phase supply for everything - nominal because we are supposed to be standardised across the EU. In practice Europe mainly uses 220V and the UK and Ireland use 240V but both fall within the permitted tolerances on 230V.
In the UK domestically we use a single phase supply which is usually single pole switched and carries a small cartridge fuse in the plug to protect the cable and appliance. The plug is three-pin with earth, although the earth spike may not be local. It has to be said that most domestic electrical kit - brown goods such as hi-fi and TV, portables such as hairdriers and shavers, and many electrical tools such as drills - are these days fitted with two-core cable and are double insulated with a double pole switch. This is because there is no polarity awareness in most of the EU - they often use two-pin Schuko plugs which can be reversed on insertion. IME even if the outlet has an earth pin - as often found in France - there is still no standard wiring for the polarity of the other two pins. This is a problem if three-pin weatherproof connectors are used - which are supposedly standard across Europe (we know them as BS4343 in the UK) - which we use with our touring caravan: they are clearly polarity marked on the body but I have only experienced three (out of many) sites correctly wired. I often wonder if they are even earthed!
A RCD is basically a pick-up coil through which the L and N cables both run. If the current through both cables is the same then there will be nothing induced in the pickup coil. If there is a current imbalance - some is flowing through you - then there will be a current imbalance in the main cables which the pickup coil will detect and trip the supply. Normally that current difference is 30mA, but for 'at risk' places such as an electronics work bench 10mA is often used. It is usual for the RCD to be on the main supply - it is often also the main supply switch as it is double pole - so if it is tripped everything goes off, not just the one circuit. More modern installations have split rings so that wired-in appliances and lighting are not protected and you don't get plunged into darkness for a simple electrical fault.
Incidently, if you wonder why our electrical outlets are such it is a historical cost thing. Most European wiring is radial - i.e. every outlet has it's own cable back to the supply board and is individually fused (or breaker) and some places (such as Germany) have outlets that are mechanically slightly different and are supplied at 6A rather than the 'normal' 16A. British and Irish wiring is almost always in a ring so the ring is fused or switched at 30A or 32A but the plug carries a fuse which may be
1/2/3/5/7/10/13A, although the Great British Public, being generally thick and unknowing, use moastly 3A or 13A.
You gave a rather good answer right up until your "the Great British Public, being generally thick and unknowing, use moastly (sic) 3A or 13A).
Does that make you the only intelligent Brit out of 65,000,000 or so then?
I think not, and I would be interested how you have managed to come to that conclusion without inspection every piece of domestic electrical equipment in the country
I think not, and I would be interested how you have managed to come to that conclusion without *INSPECTING* every piece of domestic electrical equipment in the country.
Have you ever seen any equipment on sale or tried to buy a plug retail with anything other than a 3A or a 13A fuse? Equally have you ever tried to buy fuses retail other than 3A or 13A? Ergo most (non-understanding) people will use 3A or 13A fuses as they either know no better or don't have the knowledge to go buy something else.
From a personal standpoint I tend to use 2A and 5A fuses as, IME,
3A fuses - especially on portable equipments - seem to have mechanical problems. Drop the plug and the fuse fails mechanically, but 2A and 5A don't.
A question about US installations from an interested UK reader.
If you have 3 phase power installed into a property in the US, do you get three lots of 220/110 v split phase supplies eg 110v 3phase as well as 220v 3 phase?
Or how does it installed if not?
Second question How do US power consumption meters work for 110v and 220 v split phase? or do you have two meters in the home?
Yes, I am an engineer by education and experience and we used to design product for the UK and EU countries. We're NA. I'm retired now for health reasons, but I remember being surprised the first time I came across the plug fuses. I was also surprised to discover that most equipment was sold sans power cords; it was up to the user to get those. This experience was gained as manager for a telecom compliance testing laboratory. We served NA, Europe, UK and the Pac Rim down to Australia. Every country would be similar "except" and it used to be "interesting" keeping them straight.
...
It's the same here in NA in some places, especially w/r to the earth. Hot and neutral have to be right though or you won't pass inspection. That doesn't stop the do it yourselfers from doing their own work, though, without regard to polairty. Here only generators would be often miswired, even often use multi-branches with a common neutral to make wiring easier. Some bands love the miswires because they're sure their amps are working when they hear that hum>
Ah, we'd call that whole-house protection over here. I never thought about what their trips might be current-wise. They're fairly new over the last few years. Then we also have arc-fault-interruptors; should an arc occur anywhere, even without being able to ever pop the breakers, they'll open. I haven't installed any yet but plan to - arcs are what start fires.
That's news to me. I didn't know the individual ring ckts were fused or switched. It sort of makes me shudder to think about trying to locate a ring ckt's fuse or switch.
Thanks for the response; we seldom got near the actual bldg wiring in my business unless we had to figure out an earth or neutral problem that screwed up a PBX. We had a plant for R&D and Repair in Wales and I always loved having to make a trip over there. Well, except for that long, boring trip across the pond, that is! I never got anywhere other than Wales for sightseeing and a couple trips into London some evenings, but I loved it.
In news:ic5_m.25554$ snipped-for-privacy@newsfe22.ams, Bob Minchin typed:
Oof! That's a tricky one because there are several different kinds of wye and delta arrangements for 3-phase power. You can get 120, 208, 220, 240,
360 and 480 and sometimes higher voltages for specialized industries. You'll never find any of these wye or delta arrangements in the home though. Probably the easiest way to answer is to provide a link or two. Also, these would never be found in a residence. Residential is always single-phase, split-phases into the home with 110Vac per leg,or 220Vac between the split (xfmr is center tapped for neutral and that's bonded to earth with an electrode driven into the ground).
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lol, that depends too! Yes every home or apartment has its own electric meter. I said it depends because the old analog meters are presently being switched out in favor of newer digital meters which can provide a lot more information. To read the digital meters, they only need to drive by in their vehicles and which then transmits the address and power usage details to them. The transmissions are even encrypted.
I'm sure they probably all work as in the UK, measuring kilowatt-hours. With a residence, there is no accounting for power factor of course; you take what it measures. In reality it gets explained iike it would make little difference, but from some of the electric motor (furnace, fans, etc) power factors that run for long periods of time that I see in my own house, I'm not so sure it's negligible!
Power from the grid, high voltage, is connected to the grid's transformer. This is a center-tapped transformer, which converts the single-phase input voltate into split-phase ( two 120Vac outputs w/r to the centertap (which is neutral/earth and bonded at the pole)). So coming TO the house from the transformer are three wires: The two out of phase hots, and neutral. Once in the meter, there is no ground nameing any longer since earth ground for the house is derived from a separate electrode driven into the ground. From the meter, the two hots go into the Mains panel Mains Breakers or Fuses along with the third wire, which connects to the Earth bar within the panel and which all internal ckts return their earth grounds to. Earth and Neutral are only allowed to be tied together within the Mains panel and nowhere else unless a special exception is claimed. Where the breakers hang, there are two busbars giving every other breaker the opposite phase of 120Vac. So to get 240Vac, you use a "ganged" double breaker where two adjacent buses are connected. Thus, the difference between the output side of breaker to breaker then will measure 240Vac since they are out of phase. A LOT of people like to mislabel this as 2-phase power, but that's wrong: It's called split-phase. One phase is split via the centertapped transformer providing the power from the grid. In most cases people don't care, but don't call it two phase when you're talking to anyone in the business or who is a little egotistical. Thus, residences are only equipped with 120 or 240 @ 60 Hz in the US and Canada. The 240Vac only gets used for major appliances such as our well pump, clothes drier, water heaters, things that otherwise would require very large, heavy cabling. Lights and all normal receptacle in the living areas are almost exclusively 120Vac. In 240Vac install, the Neutral isn't used though there are exceptions. Earth is always connected to anything that's not class II design.
In the event I haven't put you to sleep, which I know my verbosity has a habit of doing to people, you might check out Mike Holt's site if you'd like some good, down to earth definitions and descriptions of the many different variables that are possible. I highly recommend him and it's a "safe" site, pushing nothing nefarious or covertly.
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Hmm, looks like he's made the forums major, too;
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's been a long time since I visited his site.
And here's a popular product here in the US; don't know if they make other localized product. "Kill-a-watt meter".
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I bet that's all clear as mud, huh? I tried!
Twayne
120 ----------- ---------Mains Sw ---------Breakers Buss 120Vac to Neutral meter 240Vac Hot to Hot
120 ----------- ----------Mains Sw----------Breakers Buss 120Vac to Neutral
Neutral -----------------------------------------Bonded to Mains breaker panel
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