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| UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Reverse Polarity Mains Socket -- How Dangerous?
Hi,
Note: This post is talking about UK (220-240V mains supply) My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't. Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems 2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm? 3) Is this potentially dangerous? 4) Is getting this fixed a big (and ergo, expensive) job? Your help would be much appreciated as I've had surprising difficult finding any info about this on the web. Many thanks Andy |
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#2
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Reverse Polarity Mains Socket -- How Dangerous?
"Andrew Thelwell" wrote in message oups.com... Hi, Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. 4) Is getting this fixed a big (and ergo, expensive) job? Your help would be much appreciated as I've had surprising difficult finding any info about this on the web. Many thanks Andy Would just swaping the wires in the plug socket sort it? |
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#3
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Reverse Polarity Mains Socket -- How Dangerous?
In article .com,
"Andrew Thelwell" writes: Hi, Note: This post is talking about UK (220-240V mains supply) My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. Well, it's not a problem that goes away by itself. One of the engineers is wrong. They asked if we'd experienced any problems in the house and we hadn't. Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were No, and No. only concerned with earthing faults, not live/neutral reverse polarity type problems 2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm? Not to the appliances. 3) Is this potentially dangerous? Yes - there's no fuse in the live. 4) Is getting this fixed a big (and ergo, expensive) job? It's easy, but this and and RCD trips indicate you should have the installation inspected. I don't necessarily mean a full inspection and test, but get an electrician in to give it a quick check, and advise if anything more substantial is required. -- Andrew Gabriel |
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#4
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Reverse Polarity Mains Socket -- How Dangerous?
On 26 Nov 2006 10:50:10 -0800 someone who may be "Andrew Thelwell"
wrote this:- 3) Is this potentially dangerous? Yes. 4) Is getting this fixed a big (and ergo, expensive) job? a) switch off the main switch at the consumer unit. Check that the lights on the socket tester are now out. b) unscrew the socket. c) unscrew the live and neutral wires from the terminals. These are probably coloured red and black respectively, but may be coloured brown and blue respectively. There will be one, two or three wires to each terminal. d) look at the back of the socket, where there will be terminals marked L and N for the live and neutral wires. e) back off the screws fully and then insert the wires into the correct terminals. f) check that all wires are secure, pushed in fully and will not pull out. That includes the earth wires, which you should not have touched. g) screw the socket back, checking no wires are trapped. One wire to each terminal is a lot easier to get back than three and a double socket is easier than a single. h) switch on and check the lights on the socket tester. Check the other sockets. i) have someone who knows how to do wring look over the installation. Someone who couldn't be bothered to wire up a socket correctly will not have bothered with any other work they did, or tested it. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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#5
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Reverse Polarity Mains Socket -- How Dangerous?
1) I can't see how a single socket with live/neutral swaped can explain
a "live" reading on the neutral at the electricity meter. What exactly did he mean by "live"? I doubt both phase(live) and neutral could be sitting at 240V. Nor should it be responsible for RCD trips(which happens because the current on the phase and neutral is different - i.e. leaking somewhere). In his position I would have flicked off the main isolater and to see if the problem cleared, then switched on the MCB's one by one. Significant voltage on the household neutral (which is what I think he meant) would suggest to me that it is poorly tied to the suppliers neutral - and I'd want that fixed urgently. 2) Yes, if a faulty piece of equipment was plugged in. Don't use that socket 3) Yes, there is something odd happening and needs professional investigation. 4) Probably not a major expense, if it's an isolated stupid mistake by a professional or an isolated case of uninformed tinkering. If however it's the tip of the iceberg of a rewire by a madman, then very urgent and somewhat expensive work may be required. |
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#6
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Reverse Polarity Mains Socket -- How Dangerous?
e) back off the screws fully and then insert the wires into the
correct terminals. You're assuming it's a single isolated fault. Given that there's some bizarre behaviour, I wouldn't do a quick fix until I was quite clear about other possible faults. |
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#7
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Thelwell wrote:
My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? No, and no. Did your first engineer say what he was comparing the neutral with to delcare it "live"? (if it appeared live compared to the live conductor, then that would suggest the polarity of your supply is incorrect (unlikely!), however if he compared it to earth, it may tell you nothing of significance). I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems This is true. They detect inbalance between the current flowing in the neutral and live conductors. 2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm? 3) Is this potentially dangerous? In the normal course of operation it will not be explicitly dangerous - many countries electrical systems do not maintain correct polarisation, and yet they remain resonably safe. The real danger comes in the event of a fault that causes the fuse to blow. Even with the fuse blown the device could still remain "live" 4) Is getting this fixed a big (and ergo, expensive) job? In itself (the reversed polarity) no, it is trivial. The RCD tripping however could be due to any number of possible causes, and it will be harder to identify the culprit. Your help would be much appreciated as I've had surprising difficult finding any info about this on the web. There have been many threads on tracjing down the cause of spurious trips on RCDs in this group in the past. It may be worth googling for a few... -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#8
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Reverse Polarity Mains Socket -- How Dangerous?
On 26 Nov 2006 12:28:19 -0800 someone who may be "
wrote this:- You're assuming it's a single isolated fault. Indeed. However, fixing this one fault means there is one less problem to worry about. Given that there's some bizarre behaviour, I wouldn't do a quick fix until I was quite clear about other possible faults. I don't see how fixing this one particular fault will make any others worse. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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#9
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Reverse Polarity Mains Socket -- How Dangerous?
I don't see how fixing this one particular fault will make any others worse. What if phase, neutral and earth have all been rotated at both ends? Maybe phase is connected to the neutral position at this socket and earth to the live position (and all the colours are wrong because they've been jumbled at the consumer unit end too). I've actually seen this done on a boat. It was a corporate event, my company had hired the yacht, and the skiper proudly gave me the extension he had made up with a UK socket strip on one end and a schuko on the other. I suspect he was red/green colour blind. |
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#10
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Reverse Polarity Mains Socket -- How Dangerous?
"Andrew Thelwell" wrote in message oups.com... Hi, Note: This post is talking about UK (220-240V mains supply) My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't. He's a cowboy trying to rip you off. A new house should have an inspection certificate, so ask for a copy, then contact the person that arranged your survey and complain. You can't have both live and neutral on a neutral block or your main fuse would blow. What he has measured is the voltage between neutral and earth. If you have fluorescent lights this sometimes happens. It can happen if you have a faulty TV or video. Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. That would not cause a problem anywhere else, but should have been checked before you bought the house. The socket is not connected to anything else unless it is in a loop. Just rewire it or get the seller to correct it. My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems Depending how it is wired and what you use might make one circuit breaker trip. 2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm? It will not cause harm, but you will be switching the neutral instead of the live. 3) Is this potentially dangerous? Not unless you take something apart and think it is switched off ! 4) Is getting this fixed a big (and ergo, expensive) job? No, get a screwdriver - open the socket after witching the mains off and make sure that the L terminal is going to RED or BROWN wires and N terminal to BLACK or BLUE. If they are correct then check inside the consumer unit - then check for any junction boxes. Your help would be much appreciated as I've had surprising difficult finding any info about this on the web. Many thanks Andy There are lots of cowboys about, so don't be conned in to buying new consumer units or having your home rewired. Don't bother checking for reputable trades people with trading standards either - they don't bother checking them out and are not allowed to tell the public even if a company does have a bad record! |
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#11
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Reverse Polarity Mains Socket -- How Dangerous?
Ron wrote:
He's a cowboy trying to rip you off. A new house should have an inspection certificate, so ask for a copy, then contact the person that arranged your survey and complain. You can't have both live and neutral on a neutral block or your main fuse would blow. What he has measured is the voltage between neutral and earth. If you have fluorescent lights this sometimes happens. It can happen if you have a faulty TV or video. Sigh.... Just beware that 'ron' has a poor understanding of electricity judged from previous ramblings in usenet, and is mostly trolling... -- Adrian C |
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#12
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Reverse Polarity Mains Socket -- How Dangerous?
Ron wrote:
My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't. He's a cowboy trying to rip you off. I can't see any basis for that conclusion. A new house should have an inspection certificate, so ask for a copy, then contact the person that arranged your survey and complain. He never said the house was new, only that he purchased it recently. What he has measured is the voltage between neutral and earth. You know this how? If you have fluorescent lights this sometimes happens. It can happen if you have a faulty TV or video. It can also happen when the sky is cloudy. There is however equally little connection between the observation and your suggested "cause" Since then we've had three occurrences of the RCDs in our fuse box tripping. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. That would not cause a problem anywhere else, but should have been checked before you bought the house. Depends on what survey you paid for. The socket is not connected to anything else unless it is in a loop. Which is highly likely... My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems Depending how it is wired and what you use might make one circuit breaker trip. What makes you say that? -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
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#13
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Reverse Polarity Mains Socket -- How Dangerous?
In article .com,
Andrew Thelwell wrote: Note: This post is talking about UK (220-240V mains supply) My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't. My feeling is to trust the engineers over a meter swapper. Those are simply 'trained' for the one job and usually not even employees of the electricity supplier. Since then we've had three occurrences of the RCDs in our fuse box tripping. First, can you be clear about this? Most houses only have the one RCD in the 'fuse box'. So do you mean MCBs (circuit breakers)? An RCD is easy to spot - it has a test button on it. I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. I'm afraid that isn't the 'culprit' for anything. My questions, then... 1) Would this explain both the apparent live neutral reading in our main meter box and the tripping of the RCDs? I always thought RCDs were only concerned with earthing faults, not live/neutral reverse polarity type problems No and no. RCDs aren't concerned with earth faults - they work by looking for imbalance in the line and neutral current flow. 2) I've been using the sockets in that room with no real probles apart from the trips. All equipment (TV, XBox, amplifier, phone charger) have worked OK thus far. Is the socket likely to be causing any harm? Unlikely. 3) Is this potentially dangerous? Yes. A 13 amp lug fuse is in the line for a good reason. With this socket it is effectively in the neutral. 4) Is getting this fixed a big (and ergo, expensive) job? It *should* be merely a matter of swapping the wires to the socket. Your help would be much appreciated as I've had surprising difficult finding any info about this on the web. Like all things you have to ask the right questions to get sensible answers. -- *The e-mail of the species is more deadly than the mail * Dave Plowman London SW To e-mail, change noise into sound. |
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#14
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Reverse Polarity Mains Socket -- How Dangerous?
On 26 Nov 2006 10:50:10 -0800, "Andrew Thelwell"
wrote: Hi, Note: This post is talking about UK (220-240V mains supply) My girlfriend and I recently moved into our newly-purchased house. We wanted to get the electric meter changed but when the guy came out to do so, he reported a live reading on the neutral block in our meter box. This was potentially dangerous, he said, and he called out the mains engineers. They investigated and couldn't replicate the problem. They asked if we'd experienced any problems in the house and we hadn't. snip The house is newly purchased and obviously the electrics are sub-standard/faulty. Take up the matter with the builder and get them to come and do a full electrical test and remedy any faults. |
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#15
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Thelwell wrote: I today bought a standard socket tester and tested every socket in the house. I've found the culprit to be the mains outlet in our spare bedroom, which appears to be incorrectly wired, showing a live/neutral reverse on the tester. When I encountered this once, it transpired that some of the sockets in the house had their neutral/live terminals on left/right respectively and some, presumably a different manufacture, had them the other way round. The sparks had simply wired them all up the same way without looking. A point to check when replacing a socket. Chris |
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#16
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Reverse Polarity Mains Socket -- How Dangerous?
Dave Plowman (News) wrote:
First, can you be clear about this? Most houses only have the one RCD in the 'fuse box'. More than one RCD suggests that it might be a TT installation (i.e. it has its own earth rod and doesn't rely on an earth connection provided by the supply company). This could account for a variable voltage reading between the supply neutral and the local earth. Is the house out in the sticks and fed via a long overhead line? -- Andy |
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#17
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Reverse Polarity Mains Socket -- How Dangerous?
The message
from contains these words: The house is newly purchased and obviously the electrics are sub-standard/faulty. Take up the matter with the builder and get them to come and do a full electrical test and remedy any faults. Newly purchased doesn't necessarily mean newly built. -- Skipweasel Pay no attention to that man behind the curtain. |
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#18
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Reverse Polarity Mains Socket -- How Dangerous?
Hi all, I'm the OP,
First off thanks for all the replies -- great to get so much feedback. Let me clarify a few points... this should help with the discussion: 1) The house is newly-purchased, not a new build. It's a 1930's semi-detached 2) I may have misled when I referred to RCDs (sorry!). We have two large rotary switch type things on our consumer unit labelled "Earth-Leakage Circuit Breaker". There is apparently one on each 'loop' of the house. It is these that have tripped 3) The problem with the meter when the guy came to change it was that he was as follows: He had one of those 'mains tester' screwdrivers with the LEDs in the end that should only light up on when touched to a live terminal. However, he got it to light up on ALL FOUR terminals attached to our meter (+ in, - in, + out, - out, yes?). I don't think there was an suggestion as to the 'size' of the current though. He also got it to light up when he pressed it to the big grey block (neutral block) in the meter box, which apparently it shouldn't do. This happenend both with our consumer unit main isolator turned ON and OFF. It stopped, however, when he pulled the main fuse out of the meter box. Two mains engineers from Central Networks came out that night and tested thoroughly for almost 2 hours in our meter box and around our roof (we have overhead supply). They found nothing out of place at all. They asked if we'd experienced any oddities inside the house, which we hadn't. However, since then we have seen our Earth-Leakage Circuit Breakers (not RCDs, sorry!) trip three times. Two of these times have been due to turning on the one socket in the spare room. One other time the other ELCB tripped when my girlfriend turned on the microwave. All sockets in the house test out fine using a normal B&Q socket tester, except the one in the spare room, which shows only one light, supposedly "L/N Reverse". Hope this helps -- your further feedback would be much appreciated based on these additional details. Thanks! Andy Guy King wrote: The message from contains these words: The house is newly purchased and obviously the electrics are sub-standard/faulty. Take up the matter with the builder and get them to come and do a full electrical test and remedy any faults. Newly purchased doesn't necessarily mean newly built. -- Skipweasel Pay no attention to that man behind the curtain. |
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#19
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Thelwell wrote:
Hi all, I'm the OP, First off thanks for all the replies -- great to get so much feedback. Let me clarify a few points... this should help with the discussion: 1) The house is newly-purchased, not a new build. It's a 1930's semi-detached 2) I may have misled when I referred to RCDs (sorry!). We have two large rotary switch type things on our consumer unit labelled "Earth-Leakage Circuit Breaker". Ohhhhhhhhhhhhhhhh. Those. In that case we know a couple of things straight away. This is oldish wiring, and uses TT earthing, meaning a local earth rod with high earth impedance. There is apparently one on each 'loop' of the house. Big house then? It is these that have tripped ELCBs rarely trip in error. I think I know whats going on now. 3) The problem with the meter when the guy came to change it was that he was as follows: He had one of those 'mains tester' screwdrivers with the LEDs in the end that should only light up on when touched to a live terminal. However, he got it to light up on ALL FOUR terminals attached to our meter (+ in, - in, + out, - out, yes?). I don't think there was an suggestion as to the 'size' of the current though. He also got it to light up when he pressed it to the big grey block (neutral block) in the meter box, which apparently it shouldn't do. This happenend both with our consumer unit main isolator turned ON and OFF. It stopped, however, when he pulled the main fuse out of the meter box. OK, then we can safely ignore anything he says Two mains engineers from Central Networks came out that night and tested thoroughly for almost 2 hours in our meter box and around our roof (we have overhead supply). They found nothing out of place at all. And we can safely conclude nothing is out of place at all with your supply as far as the CU or fusebox. They asked if we'd experienced any oddities inside the house, which we hadn't. However, since then we have seen our Earth-Leakage Circuit Breakers (not RCDs, sorry!) trip three times. Two of these times have been due to turning on the one socket in the spare room. One other time the other ELCB tripped when my girlfriend turned on the microwave. All sockets in the house test out fine using a normal B&Q socket tester, except the one in the spare room, which shows only one light, supposedly "L/N Reverse". OK, I think I see the problem clearly. An ELCB will trip when it sees large earth currents (unlike RCDs which trip on small earth currents). This means you have a major fault in whatever appliance caused it to trip when the socket was switched on. So the microwave and whatever was plugged into the spare room socket should be taken out of service now, and some checks done on them later to confirm or deny theyre the problem. From everything you say, the only problem with the installation itself is the swapped wires behind a socket, which is a trivial matter easily fixed in 2 minutes. Your 2 faulty appliances would not have tripped anything at your last house, which I can conclude had low impedance earthing and no RCD. However on a high impedance earth, which you have here, such faulty appliances are not safe to use at all. NT |
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#20
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Thelwell wrote:
Hope this helps -- your further feedback would be much appreciated based on these additional details. Thanks! Andy Which brings us to the next question, how best to test your probably faulty appliances. A low cost multimeter can be used to test resistance from E to L&N pins on the plug, while its not plugged in, and any controls on the item are set to on. However if the thing has any electronic power controls, as many appliances now do, this wont test it fully. Plugging an item into an RCD into a socket would quickly detect any appliance with an earth leakage fault. Since it looks like you've got at least 2 bad appliances, I'd get an RCD plug, make it into a short extension lead, and have it to test things with. Its a minor plus that youve got ELCBs and not an RCD, or you'd have had bigger problems. NT |
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#21
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Reverse Polarity Mains Socket -- How Dangerous?
OK - the extra info helps.
I think you have an older TT installation. This means because your supply comes in on overhead wires, the earth is provided by you - the customer, and not by the electricity company (who only supply live and neutral). Because customer supplied earths are considered less reliable, slightly more elaborate protection is provided at the consumer unit (hence your 2 ELCB's). However ELCB's are the older way of doing it. Now they use RCD's - which are considered more reliable. (Basically an RCD will work correctly regardless of how good or bad your earth is, whilst an ELCB may not). One option available is a replacement consumer unit with appropriate RCD's (TT installations usually have 2, one less sensitive one for the whole house, followed by a second more sensitive one just for the ring mains). Another option is to have the TT supply upgraded to TN-C-S (also known as PME) as well as a simpler single RCD consumer unit (IMO this is the better option). Either way I would still have your installation checked out by a professional, and your earth tested (check they are able to do this). Regarding the dodgy socket - it could have all 3 wires transposed (live is connected to neutral, earth to live, and neutral to earth). This would explain why very low powered devices could be plugged in and work ok (because they usually don't pass enough current to trip the ELCB), but anything larger does. Bear in mind some plug-in socket testers are unable to detect earth/neutral transposition. |
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#22
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Reverse Polarity Mains Socket -- How Dangerous?
OK, I think I see the problem clearly. An ELCB will trip when it sees
large earth currents (unlike RCDs which trip on small earth currents). This means you have a major fault in whatever appliance caused it to trip when the socket was switched on. So the microwave and whatever was plugged into the spare room socket should be taken out of service now, and some checks done on them later to confirm or deny theyre the problem. It could still be a fault on that socket - and the devices are performing correctly. For instance, the microwave could just happened to have been switched on just as the device on the faulty socket decided to draw more power (e.g. a phone charger cycling). A low power device may just be apparently working ok, even though it's passing current between live and earth (because of faulty household wiring) - just not quite enough to trip the ELCB all the time. However if always operating the microwave on a believed good socket causes a trip, then your explanation and not mine becomes the prime suspect. |
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#23
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Reverse Polarity Mains Socket -- How Dangerous?
On 26 Nov 2006 12:47:52 -0800 someone who may be "
wrote this:- I don't see how fixing this one particular fault will make any others worse. What if phase, neutral and earth have all been rotated at both ends? Then the socket tester would have indicated faults with most of the other sockets. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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#24
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Reverse Polarity Mains Socket -- How Dangerous?
On 27 Nov 2006 02:18:11 -0800 someone who may be "Andrew Thelwell"
wrote this:- 2) I may have misled when I referred to RCDs (sorry!). We have two large rotary switch type things on our consumer unit labelled "Earth-Leakage Circuit Breaker". Do these things look as if they are 30 years old, or more recent? There is apparently one on each 'loop' of the house. It is these that have tripped What do you mean by 'loop'? Could you put a photograph of the above and the consumer unit on the web somewhere? 3) The problem with the meter when the guy came to change it was that he was as follows: He had one of those 'mains tester' screwdrivers with the LEDs in the end that should only light up on when touched to a live terminal. Notoriously unreliable gadgets, largely useless. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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Reverse Polarity Mains Socket -- How Dangerous?
Then the socket tester would have indicated faults with most of the other sockets. Not if it was a spur. (which is most likely for a badly wired add-on) |
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Reverse Polarity Mains Socket -- How Dangerous?
Hi, OP here again,
Thanks for the further feedback. A few more responses: 1) I would doubt that the appliances in the spare room are faulty, to be honest. They are all very new items: an LCD TV, XBOX 360, amplifier, laptop... all new or nearly new (nothing older than 18 months). The socket in that room shows up reversed on my plug-in tester but apart from twice tripping the ELCB, everything works just fine. 2) The ELCBs look like they may be anything up to 30 years old -- they don't have a modern look to them, although I've tested them both and they work fine. I'll try to put up a photo online later. One controls the kitchen sockets and lights, while the other covers everything else in the house. 3) The microwave has tripped the kitchen ELCB once and once only when being turned ON. The 'reversed' spare room socket has (so far) caused two trips of the other ELCB - once when turning ON the switch (even though no appliance were actually in operation, although I guess the LCD TV and XBOX may draw power right away as they have 'stand by' type function, yes?). The other time it tripped, it was when I turned the socket OFF (after charging a battery in there for 24 hours+). Does this give more clues? 4) My plug-in mains tester does not detect earth-neutral transposition explicitly (it doesn't have it as an option) Thanks, Andy wrote: Then the socket tester would have indicated faults with most of the other sockets. Not if it was a spur. (which is most likely for a badly wired add-on) |
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Reverse Polarity Mains Socket -- How Dangerous?
On 27 Nov 2006 06:36:48 -0800 someone who may be "Andrew Thelwell"
wrote this:- 2) The ELCBs look like they may be anything up to 30 years old -- they don't have a modern look to them, although I've tested them both and they work fine. I'll try to put up a photo online later. One controls the kitchen sockets and lights, while the other covers everything else in the house. I'll be interested in the photographs. My initial thought was that they might be voltage operated devices, but it would be difficult to install two in one installation. 4) My plug-in mains tester does not detect earth-neutral transposition explicitly (it doesn't have it as an option) AFAIAA none of them do, because it would be difficult to do in a cheap bit of equipment. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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Reverse Polarity Mains Socket -- How Dangerous?
On Mon, 27 Nov 2006 15:41:03 +0000 someone who may be John Rumm
wrote this:- OK, then we can safely ignore anything he says Yup... I am supprised that somone doing this type of job is trusting his life to one of those toy screwdrivers! Presumably that is the level of training they get now. -- David Hansen, Edinburgh I will *always* explain revoked encryption keys, unless RIP prevents me http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54 |
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Reverse Polarity Mains Socket -- How Dangerous?
In article . com,
Andrew Thelwell wrote: 3) The problem with the meter when the guy came to change it was that he was as follows: He had one of those 'mains tester' screwdrivers with the LEDs in the end that should only light up on when touched to a live terminal. However, he got it to light up on ALL FOUR terminals attached to our meter (+ in, - in, + out, - out, yes?). I don't think there was an suggestion as to the 'size' of the current though. He also got it to light up when he pressed it to the big grey block (neutral block) in the meter box, which apparently it shouldn't do. This happenend both with our consumer unit main isolator turned ON and OFF. It stopped, however, when he pulled the main fuse out of the meter box. Neon screwdrivers are notoriously unreliable. However, with an overhead supply it's quite common to have a few volts from neutral to true earth, and that's what his screwdriver was seeing. -- *When companies ship Styrofoam, what do they pack it in? * Dave Plowman London SW To e-mail, change noise into sound. |
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Reverse Polarity Mains Socket -- How Dangerous?
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Thelwell wrote:
Hi, OP here again, Thanks for the further feedback. A few more responses: 1) I would doubt that the appliances in the spare room are faulty, to be honest. They are all very new items: an LCD TV, XBOX 360, amplifier, laptop... all new or nearly new (nothing older than 18 months). The socket in that room shows up reversed on my plug-in tester but apart from twice tripping the ELCB, everything works just fine. Theres something more going on if that skt trips the elcb. Fix the socket polarity swap first, test your appliances for earth leakage. Either a leaky appliance (you have a lot of faith in new goods), a miswired exntesion lead or a n/e swap. 2) The ELCBs look like they may be anything up to 30 years old -- they don't have a modern look to them, although I've tested them both and they work fine. I'll try to put up a photo online later. One controls the kitchen sockets and lights, while the other covers everything else in the house. photo might tell us if theyre i or v operated, which would help. 3) The microwave has tripped the kitchen ELCB once and once only when being turned ON. The 'reversed' spare room socket has (so far) caused two trips of the other ELCB - once when turning ON the switch (even though no appliance were actually in operation, although I guess the LCD TV and XBOX may draw power right away as they have 'stand by' type function, yes?). The other time it tripped, it was when I turned the socket OFF (after charging a battery in there for 24 hours+). Does this give more clues? yes, but nothing definitive. NT |
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Reverse Polarity Mains Socket -- How Dangerous?
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Reverse Polarity Mains Socket -- How Dangerous?
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Reverse Polarity Mains Socket -- How Dangerous?
Hello again all,
I've put up a photo of our consumer unit and a close-up of one of the ELCB's. They can be found he http://www.andythelwell.com/cu.jpg http://www.andythelwell.com/elcb.jpg both are high-res photos Your help is appreciated! Thanks! Andy Andrew Gabriel wrote: In article .com, writes: ELCBs rarely trip in error. I think I know whats going on now. ELCB's frequently trip in error conditions outside the house, over which the householder has no control, such as overlapping earth resistance areas, and other causes of external ground currents (lightning being a common one, and someone else's earth leakage being another). This is why they have a bad reputation for false trips. -- Andrew Gabriel |
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Reverse Polarity Mains Socket -- How Dangerous?
In article .com,
"Andrew Thelwell" writes: Hello again all, I've put up a photo of our consumer unit and a close-up of one of the ELCB's. They can be found he http://www.andythelwell.com/cu.jpg http://www.andythelwell.com/elcb.jpg both are high-res photos They are RCD's, not [voltage operated] ELCB's. RCD's were originally called current operated ELCB's (14th Ed Regs), but that name didn't stick. -- Andrew Gabriel |
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Reverse Polarity Mains Socket -- How Dangerous?
In article ,
(Andrew Gabriel) writes: In article .com, "Andrew Thelwell" writes: Hello again all, I've put up a photo of our consumer unit and a close-up of one of the ELCB's. They can be found he http://www.andythelwell.com/cu.jpg http://www.andythelwell.com/elcb.jpg both are high-res photos They are RCD's, not [voltage operated] ELCB's. RCD's were originally called current operated ELCB's (14th Ed Regs), but that name didn't stick. Come to think of it, the other give-away is that you can't have multiple [voltage operated] ELCB's on one installation. -- Andrew Gabriel |
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Reverse Polarity Mains Socket -- How Dangerous?
The message .com
from "Andrew Thelwell" contains these words: I've put up a photo of our consumer unit and a close-up of one of the ELCB's. This house of your - the roof timbers haven't got "The Ark" burnt into them somwhere, have they? -- Skipweasel Pay no attention to that man behind the curtain. |
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Reverse Polarity Mains Socket -- How Dangerous?
Andrew Gabriel wrote:
In article .com, "Andrew Thelwell" writes: I've put up a photo of our consumer unit and a close-up of one of the ELCB's. http://www.andythelwell.com/cu.jpg http://www.andythelwell.com/elcb.jpg They are RCD's, not [voltage operated] ELCB's. RCD's were originally called current operated ELCB's (14th Ed Regs), but that name didn't stick. ....and this changes everything. Any appliance you plug in that trips it is liable to be leaky, but no guarantee its that one. I had assumed they were voltage operated elcbs. Get used to trips and having to throw out appliances that work ok. NT |
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Reverse Polarity Mains Socket -- How Dangerous?
In article . com,
wrote: No, an elcb doesnt care how bad the earth impedance is, it will still work. And even old ELCBs are still orders of magnitude more reliable than rcds. You jest? We used to use them on 'The Bill' camera setup when running from mains, (obviously). If the camera touched anything vaguely conductive it would trip. Even just setting it down on the ground. -- *How do you tell when you run out of invisible ink? * Dave Plowman London SW To e-mail, change noise into sound. |
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