Flickering room lights and occasional total power loss. Possible causes?

[me]

I've been experiencing very brief flashing of my ceiling lights although they are on separate circuits upstairs and downstairs and while I had a lamp plugged in to the mains I'm pretty sure I saw brief flickering as well. It's quite intermittent but I had a total power loss for probably less than a second a couple of days ago and decided to phone the electricity board and they wanted to send a man around, they said at no cost, as they consider this an emergency situation but I put them off temporarily because I want to try to determine whether it is on my side of the circuit where the fault may lie first.

I installed the consumer unit myself several years ago and as I say the lights are on separate breakers and the fact that it seems to be affecting the power sockets would lead me to think that if the fault is on my side of things then it'd have to be the main 100A power switch on the consumer unit. I turned all the power off and toggled the power switch on and off several times thinking that might "clear" the fault but it's still the same.

So any ideas as to where the fault might lie (assuming it's on my side of things) and what I could do to test for it?

[Andy Burns]

Check with a few neighbours if they've noticed anything (remember they will be spread over multiple phases) could be a fault underground, on poles or in substation.

If you're confident then isolate the supply and tighten all screw terminals in the CU, obviously avoid the live side of the main switch.

Other than that, let the supplier come out and do whatever tests they see fit, they'll tell you if you need to get your side fixed, or they'll fix their side.

[Tim+]

Is your house supplied by an overhead power line? If you've noticed flickering on both the lighting and mains circuits I would have thought that the problem is with your incoming supply, not your wiring.

Tim

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[me]

I forgot to say that I asked if there had been any problems reported in my street and he said there hadn't - I can't imagine I'd be the only one affected. Also I'm fully confident with electricity as I installed everything from the tails inwards.

The funny thing is that my supplier has been trying to get me to have a new smart meter fitted and I refused. A couple of weeks later and this fault starts happening. Coincidence ... you decide! LOL!

[Archibald Tarquin Blenkinsopp]

If you are not seriously affected a 240V coil relay can give an indication of a power fail.

Feed the coil through an n/o contact. Add a reset button across the contact, stick it in a box and drop it across live and neutral of the supply you wish to "monitor".

I bought a load of these relays and bases from Ebay. They take a while if you want cheap, as they are shipped from China.

I have a loose connection on the fitting in the bathroom, no problem with the diagnosis though, it's arcing is fairly easy to hear. [CFL bulb]

AB

[Andrew Gabriel]

Mains filament lamps (ideally not halogen) are very good for showing momentary dips and surges, as the change in light level is amplified many times over the change in voltage that causes it. If you aren't using them anymore, find an old one and use it as the main light in your room, and you will soon see what's happening with mains voltage dips/spikes.

[Archibald Tarquin Blenkinsopp]

(ideally not halogen) are very good for showing

Agreed totally, but the relay approach "remembers" the blip in power and by dropping it across the lighting source or ring main [fuse advised] the interruption will be remembered.

I squirted a can of WD 40 into the pull switch before the noise told me I was on the wrong track. A loose wire in a JB in the loft would not be easy to pinpoint.

AB

[Brian Gaff]

Well first ask the neighbours. That will at least tell you if its really local. Get a medium wave radio when it happens and see if you can hear any arcing sounds in your house. Personally I'd have accepted their offer as they could have done the neighbour checks etc with a little more authority in case you do not get on with a neighbour. I do remember some 2 years ago something similar happened to a friend of mine. It was eventually traced to a jury rigged Canherbis farm in a property in the same road. Brian

[Brian Gaff]

Yes coincidence. I' m afraid, I seriously doubt any company has the time or inclination to target one customer. They just do not seem too bothered about Smart meters at the moment. If you have a nearby street light see what that does. Brian

[harry]

Plug some table lights in. If they also flicker, the whole house is affected. The first thing to do is check for loose screws in your consumer unit.

[Chris J Dixon]

Could the main fuse be making poor contact?

After I pulled the fuse to change a CU some years ago, there was an issue that I didn't spot affecting the contact surfaces. I experienced occasional supply dips, and eventually noticed overheating of the fuseholder.

They were round to sort it in very short order.

Chris

[tabbypurr]

The bad contact could be almost anywhere, either your side or supplier's. 'Pretty sure' is a recipe for failure at this sort of thing, you need to determine your facts for sure before applying logic. If you wired the house yourself I'm sure you are entirely capable of figuring the rest out. Well, unless you used, as I once encountered, broken bulbholders & bare twisted wires for JBs, bell wire for lighting circuits et el.

NT

[Clive Page]

We had similar problems some years ago. It turned out that the electricity company's main fuse for our flat was in the hallway of the block, and when we eventually located it and listened to it there were sparking noises coinciding with the flickering of our lights. Since the fuse unit was sealed up, I reported it to the company and they treated it as a high priority case (a possible fire risk perhaps?) and sent someone out to replace the fuse very quickly. This may not be your problem, but worth investigating.

[Archibald Tarquin Blenkinsopp]

I found a LW radio is more effective, but it's difficult to pinpoint the defective circuit as the surrounding wiring retransmits the noise pulses.

AB

[Dave Plowman (News)]

Flickering would suggest a poor connection somewhere.

Increase the load to see where the smoke comes from. ;-)

[Archibald Tarquin Blenkinsopp]

I am reminded of the time when I had the flickering lights episode. I was just about to depart on a seven hour trip to Belfast when the lights started flickering.

The old part of the house was protected by an ELCB, this was the problem. Swopped it for an RCD on my return, but that morning was a nightmare trying to wheel the freezer and fridge to within extension reach of a bedroom.

I did think the supply company were at fault initially though, every supply pole up to the house produces a frying noise, proportional to the amount of humidity. The first action was training binoculars on neighbours windows to see if they had the problem. Probably not something to be encouraged as a diagnostic tool.

AB

[me]

Quick update, might be useful for future readers with the same problem.

I turned all the electricity of at the consumer unit and pulled out and forcefully reseated the main 100A supply fuse on the provider side of the meter several times. So far no more flickering lights so fingers crossed.

By the way this was prompted by comments above so thanks to those people.

Only thing now is I noticed my meter disc is still very slowly rotating even when all electricity is off! Do the problems never end?

[Archibald Tarquin Blenkinsopp]

You have discovered perpetual motion. Congratulations!

Interrupting the power might have created a small "weld" across the high resistance contact with the repeated "surge".

I have always found with intermittents, it is best to do nothing but observe and test with as little disturbance as possible to the suspected circuit.

That's not to say that there is anything wrong with your technique it's just nice to be able to narrow things down to a particular component or connection. Intermittents can come back at the most inconvenient times.

AB

[me]

I suppose so but the only things left in circuit, because I switched the main breaker on the consumer unit off, are the 100A supplier fuse, the tails from this to the meter, the meter istelf and the tails from the meter to the consumer unit.

So, unless the fault is in the meter itself, I'm pretty confident that the fault was in the contacts on the supplier's 100A fuse which I have now cleared with the repeated reseating.

Strangely the 100A fuse has now got one of those little metal tags on it to stop tampering that never used to be there. No idea how they got that on but the meter is in a shared alleyway so my neighbour must be complicit (annoying bugger)!

[me]

For the eleven years I've been at this property there's been no fault whatsoever, then two weeks after being cajoled by my provider and me refusing to take a smart meter this fault happens. I was only joking that it was possibly them causing the fault but you have to admit that is one hell of a coincidence!