House electrical problem?

Hi there Is there anything, (apart from spikes) that could be wrong with an electrical supply that would cause what appears to be higher than average failures of electrical items?

I have had the electric company come out and do a test which involved leaving a device plugged into a socket over a weekend and they said the results were fine, with a good earth. Recently our landlord had an electrician come and do something which involved taking all the bulbs out of the lights and plugging another device in for 20 minutes or so, again it got the all clear.

Yet we seem to go through electrical items very quickly, the most recent being my PC monitor which burned out at the weekend. The kettle went a couple of weeks ago, my PC PSU went bang just before that, the transformer in a VCR went, our TV died a few times after repairs, bulbs blow frequently, the cooker went bang about two months back, the red lights on sockets in the kitchen blew etc.

So is it just coincidence or could there be something wrong with the supply that the above tests don't look for or missed due to the short test period?

It's an AC UK supply.


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The mind boggles.

If you have a TN-S system (see uk.d-i-y FAQ for supply type identification:

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) then a connection between neutral and earth in your house or in the supply near your house can cause voltage spikes which significantly shorten the life of filament lamps. The spikes happen when someone else on a different phase has an accidental short to earth, so it would only be likely to show up significantly in a residential area where there are many homes on a 3-phase circuit with TN-S earthing. Never heard of it damaging other appliances though. If you have RCDs and the neutral-earth short is on the load side of them, it will cause them to trip usually.

Another possibility is someone on your supply, probably a different phase, is running a load like a heavy duty arc welder. This might cause spikes due to neutral impedance. Filament lamps are particularly sensitive to fluctuating supplies -- it causes amplified fluctuations in their light output. Is any such effect visible?

In the worse case of a disconnected neutral in the supply and you getting something approaching the 400V phase-to-phase voltage momentarily, I can't see that blowing neon lamps on socket outlets unless it was for a sustained period.

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Andrew Gabriel

In lay terms, almost all failures in electrical equipment are caused by too much voltage or too much heat. Too much voltage is either short term - spikes - or long term - "overvoltage". Overvoltage that is not sufficient to break down insulation immediately, does so long term by creating more than usual current which causes larger fields and weakens insulation thru heat, e.g., running a 230 volt appliance at

400 volts for a second

Too much voltage from spikes can be from a carpet, from loose connection in a neutral anywhere in the system, from nearby equipment like welders, ham radios, power lines, from a bad motor brush, or even nearby autos ( a few feet from a line) with bad shunt capacitors.

The best way to check it out for spikes is with a fast oscilloscope - the spikes should show on the screen.

Overvoltage - a reliable meter. But I think they did some of this:

I think this was a simple earth-ground checker.

Not sure what this one does.

bulbs blowing and cookers going, etc, suggests that for a second or so the voltage went up, rather than spikes - the elements in these devices are fairly forgiving of spikes, but get hot rapidly if overvoltage of a second or so duration occurs.

I am not familiar with the specifics of the UK power grid, i.e., if the 230 volts is one single phase conductor or if you use two phases and create a neutral in your residence, but if it were a US single phase 240 where one wire is used with a neutral grounded conductor to get 120 volts, we would be looking for one phase near to and occasionally touching a neutral somewhere in a box, which would give 240 volts on that 120 volt line for a short period. If it were a three-phase sytem, we would be looking for phase-to-phase voltage occuring instead of phase to neutral, for a similar reason.

To troubleshoot for this intermittent overvoltage, I would turn on a bulb in a socket known to blow frequently, and walk about hitting the wall with the bottom of my fist near where - NOT ONTO - boxes, outlets, switches, etc., are located, as someone watches the light. if you have a bad connection in a box or wire, the light will change brightness as you hit near the box. Same test for the mains box - but that is usually done with an insulated mallet, to prevent the coroner from verifying that you had indeed found the problem, and that the problem was indeed a short inside the mains box.

Hope it helps. Good luck.

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I had a similar problem with lamps (filament, fluorescent and sodium), tv, video, cash register, coolers, fridges and a whole range of other items constantly going wrong. Our electric company plugged a data recorder in for two weeks and eventually traced the fault to other peoples "economy 7" cutting out all at the same time (11pm) causing an over voltage of the system. They then dropped the supply voltage from their transformer and all has been fine since. The supply company then connected another data recorder for another week for reassurance purposes. I don't think 20mins or two days test is enough to highlight a problem like this, but it may be worth your while asking your neighbours if they have the same problems, at least 5 doors either side. I asked the site next door to us and they were also blowing a lot of lamps which also suddenly stopped after the electric company been. Regards, Paul F.

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Thanks for the replies. Our electric went off yesterday, (uncommon really) for about 5-10 seconds and now the video won't work. Switch it off and on and it comes on briefly then goes off again. Sigh.

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Thanks for the replies, much appreciated.

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