The wall between our dining room and living room has a single light switch controlling 4 40-watt uplighters and 2 sockets on the dining room side. On the living room side sit the sockets for our TV/Cable box/broadband router and my NAS server.

In recent weeks, every time someone switches the light in the dining room on or off or switches on something at the socket, it momentarily cuts the power to the sockets in the living room. Generally only the TV is affected, but sometimes it cuts the AV amp or broadband router and a couple of times the NAS server has been knocked out.
On one occasion, I plugged the iron in in the dining room and it tripped the whole ring main. Most inconvenient.

As we rent the property, we called the agency and they sent round an electrician. He fiddled with the switch and then said that he had a similar TV and it was just that they were a bit sensitive. Unfortunately, I wasn't home when this occurred, or I might have been a little more insistent on a more satisfactory resolution to our problem.
The next thing we have been advised to try it removing the bulbs from the dining room lights, presumably as low-energy bulbs draw a bit of power when starting up. I tried this (sceptically) and sure enought, it has the same effect with traditional bulbs or no bulbs at all.

I've reported this back to the agent and I'm hoping for a bit more effort from the electrician.

Anyone here have experience of this type of problem? There is no evidence of damp in the wall and the issue has definitely got worse in recent weeks. We haven't drilled into the wall or otherwise disrupted the cabling.

So you've got 2 sockets controlled from the lighting ring? I'm not a sparky but that doesn't sound right. Is it likely old wiring? Maybe worth insisting a safety check is done.

I don't think that's the case, szkom. To be clear, when the iron tripped the circuit, it was the sockets, not the lights that went off. It seems more that there is somehow an inappropriate connection between the lights in the dining room and the sockets on both sides of the wall. The socket where I plugged in the iron is roughly opposite the living room sockets and appears to have a separate fused switch, though I don't know why.

I'd guess the wiring is under 20 years old and maybe considerably more recent. As to who did it, I know not.

Here's your problem

Sounds very dodgy. I would get a registered electrician (i.e. NICEIC, ELECSA or NAPIT) to take a look. Was the sparky sent round by the lettings agency registered? Sometimes they use 'odd job' people who aren't qualified. If I read it right, you are saying that both lights and two 13amp square pin (i.e. normal) sockets are being controlled by a wall switch? If so, that is definitely unacceptable. The lighting circuit should be separate from the sockets circuit. Re. the iron, I would suspect that the iron itself is the culprit. The fused switch for an extension socket is ok, it's known as a 'fused spur' and the purpose is to ensure that a single-cable spurred off the ring circuit can't draw over 13 amps, which could overload the cable.
Reading your post again, if the sockets went off leaving the lights on, that suggests that they are indeed on separate circuits. The TV problem might possibly be caused by arcing in the lightswitch producing RF (radio frequency) interference. Changing the switch will fix that.

Very helpful, wink, thanks. Less helpful, Tim, but thanks anyway - any time you fancy ironing my shirts for me...!

The only connection between the (all 13A square pin) sockets and the light main is that the light switch seems to cause the TV / other appliances to suffer a momentary cut/dip in power.
The iron could be the problem, yet seems to function fine when plugged in to any other socket. The fused spur sounds exactly right, as the wall was originally external, so I'm guessing they just took a spur from the house and chased the cabling in when they closed in the area that is now the dining room.

Would the RF interference cause the TV/other appliances to cut out? How does this explain the same effect caused by the socket (some 12 feet from the light switch, but just a couple of feet through the wall from the socket)?

I think you are right about the agency using an odd-job type. If they don't send a proper guy next time, I'll make a fuss.

Thanks again.

In the meantime, invest in a cheap UPS such as this to keep your gear happy

If you think RF is causing the problem take an old AM radio and walk around the house switching things on and off. If you've got interference significant to turn your telly off, you'll hear it on the radio.

Although it sounds more like a temporary brown out to me.

Maybe those sockets are wired of the lighting circuit or partially wired. Just an idea Jim as i know fudge all about sparks.

OK, have a clearer picture now. So basically plugging in appliances or using the light switch in the dining room causes momentary disruption to the living room (TV etc.)?
That sounds as though maybe the mains voltage is dropping - brownout as referred to above. It all says there's something awry, so I would definitely insist on a qualified sparks from the lettings agency. Very bad news for them if your house caught fire anyway.

Something not right
First things first change the light switch to a decent branded one MK or something similar
If it continues then there is something wrong with the wiring (condition) or somebody has done some dodgy wiring
There are so many things it could be, it's difficult to guess on here
But definitely get somebody that knows what they are doing to check it out

Just read it again don't quite get your wiring! you shouldn't have a light switch controlling socket outlets they are not rated to do that normally 5 amps although you can get some that are 20 amps (is this what you mean)
Or do you mean you have a switch spur that has sockets and lights fed from it and fused seperatly?

Hope you sort it!

This is exactly the situation, the light switch does not (intentionally) control any sockets and shouldn't share any wiring.

I spoke to the electrician this afternoon, who still thinks it may be related to the TV or Virgin Cable box (which is - coincidentally, I think - also fritzed). I'm going to talk to the guy again after Virgin have given us another useless Samsung piece of junk.

I tend to agree that it needs a little more urgency on the part of the sparks, but maybe the agency don't want to spend the cash.

So, Virgin came round this morning and, as expected, replaced the Cable TV set-top box. This is our third in as many years - it seems as though Samsung have dumped a real dog on Virgin.

Anyway, MrsC has carried out some empirical testing and it seems as though the light switch no longer disrupts the TV. I have no idea why this should be, unless the Virgin box was so on the edge that it was cutting the signal at the slightest change in voltage. It doesn't explain the server cutting out, unless the Virgin box itself was causing some problems?

I'll have a look myself when I get home, but it looks like it might be fixed. Or have stopped happening, at least.

...until you plug the iron in...

Well quite.

Meh. Got home, flicked switch, TV cut out...

Stop flicking the switch?

You need to get this looked at. Tell the letting agent you can smell burning....the sparkie will get sent round asafp.


Roy

Really should get a spark round, before your landlord rents out the property he should have an electrical safety check, up here that's usualy an electrical installation condition report.

Without being there I could only guess, firstly have a wee smell around the affected electrical points, if you feel competent enough undo the face plates and look for signs of burning, not really up to you to find the fault though.

If the problem is getting worse and affecting both circuits but both circuits can be individually isolated by a breaker then it could be a shared neutral which is not making a proper contact which can cause over heating at that point.

How long does the tv go off for and is it staying off for longer than before, try plugging a standard lamp into the affected socket with a standard bulb, it would turn off right away as some tv's stay on for a bit.

Never rule out coincidence, it's a bugger.

Your first sentence I think is misleading Jim!

As I understand it you have two sockets in the dining room on the partition wall (which used to be an external one), also a single light switch. In other words the dining room has been created recently by enclosing its space and it needed power and light.

Your fuse box should have labelled fuses - if you turn off the circuit breaker for the lights try plugging in the iron and see if that still causes a problem.

Now stop me at this point if I'm off the mark but it would be reasonable to assume that the lighting "feed" cable and the "power" feed cable (the fused spur) are routed along the same channel at some point. It's possible there is a short circuit in this area.

One might think that the power points in the dining room are fed from the point immediately through the wall in the living room. You can check this if you unscrew the faceplate from the latter to see if it has 3 wires coming from each terminal at the back of it. (2 for the existing ring main and one spur).

You clearly have a bad connection somewhere.

What I would do first is (with a safe screwdriver - one that shows live wires on contact) remove the faceplates as Sparkers says one by one and gently tip the top towards you so that you can squint inside. Here are some things to look for:
1. a burnt-looking end to any wire
2. a loose wire in any terminal
3. where two wires enter the same terminal they can
become loose if not tightened properly initially (shoddy
installation)
4. defects in the sleeving which could cause two wires to
come in contact with each other - check earth wires and
their sleeving particularly.

Start with the light switch. No way should this have been wired to the power supply, but to the lighting circuit.

If you continue the search with the power points and all the above seem fine you may be looking at a short circuit between the power supply and the lighting supply.

When all's said etc., the letting agency has no business to be taking money off clients when there's potential danger in the property. Sounds like the attempts to inspect so far have been pathetic.

My mistake, you are all correct! Missing comma alters meaning fiasco! I hang my grammatical head in shame!

The light switch controls the uplighters. There are 2 sockets. There is theoretically no connection between them.

I'm going to call the electrician again this morning. I agree with all of you that this needs properly sorting.

There damned well should be... I bet Sparkyman sees it as well.

Assuming the extension features mod cons such as earthing.

I would say there is proberbly a crossed/shared neutral and you have an item with some earth leakage.
Is the consumer unit a split rcd board? Is it an rcd tripped or just an mcb? I've seen where they just put the neutrals into any neautral without any thought causing nuisance trips.

OK, to the layman, there is no connection in their operation; the light switch does not control the sockets.

Sheesh, a guy makes one grammatical error...

As said previously change your light switch to a decent one, crap switches can cause no end of issues.
also are any of your lights low voltage i.e requiring a transformer these also can play havoc on circuit's
Failing that as said above loose connections can be another major cause of stuff like this
Be careful peeling off socket outlets and spurs etc. sometimes people have just tried to cram in far to many wires and they can end up coming loose or breaking if excessively bent!
Best to leave that to an Electrician, unless you are confident enough! they can cuase a nightmare especially if they are cut very short!
Its like anything armchair diagnosis is very difficult at times, so you do need to rely on a decent electrician being at the property to diagnose!
Dont let them go until its sorted!

Thanks everyone. As it's not my house, I'm not going to put my tools anywhere near the electrics. At the moment it's their problem; if I screw up it becomes mine!

I'll call the agency again this morning and reiterate that I want it sorted by an approved electrician.

I'm slightly concerned that although the dodgy Virgin box wasn't causing the problem, an electrical issue might be damaging the Virgin box. And maybe my server...

Very plausible it may. Perhaps worth saying that you've had a virgin box replaced, however it's been suggested that the problems with the electric have caused the failure.

Just spoken to the agent; they will try to get the sparks back in.

This is the reply from a second electrician to the agent:

"I would not expect the dining room light to affect the TV in the back sitting room or to throw out the computer server ? as the lighting circuit is not connected to the socket circuit which supplies the TV, virgin box and the computer server which are plugged into the socket circuit, the only thing that might affect the TV digital signal from the lighting circuit is if the dining room light or switch is arcing which could cause interference to the signal of the TV or the wireless computer server if there is one ? but this is highly unlikely as the lighting circuit is a separate circuit from the socket circuit. I would probably have indicated that the virgin system is at fault the same as Ivan from the information supplied by the tenant, as I would presume that the TV system signal is also supplied via the virgin system along with the computer server which I would also presume is via the virgin system, as the tenant has a new virgin box was this installed and checked by virgin to see if it was working correctly or was it installed by the tenant if it was installed by the tenant it may be that the incoming system would need to be checked to see if the signal is at the virgin box ? if it is found that the virgin system is working correctly, i would recommend that the socket and lighting circuits are tested and checked to see if there is any fault causing this problem, but if there was an electrical fault as indicated I would have thought that the RCD would have tripped out on the circuit causing the problem, which the virgin system is plugged into, but as indicated by the tenant there has been no tripping of the socket or lighting circuits."

Well, the Virgin box was installed and checked by the Virgin technician. The computer server is wired, not wireless. And the sockets did trip when I plugged in the iron the other day... Ho hum.

The only other possibility is the Onkyo A/V amp, which is not the world's most reliable piece of kit and the TV and Virgin box are both plugged into it. However, generally, if anything upsets the amp, it cuts out for about 20 seconds while it resets, whereas this is simply a 2 second problem.

Has the second electrician actually been to see the problem himself? If not, he's wasting a load of words telling you what he expects. Sparky needs to turn up & test all circuits, simple. You can't assume that there's no fault because the RCD hasn't tripped.
One other thing comes to mind - is the TV etc. plugged directly in to the socket, or is it via one of those 4 way or 6 way extension blocks? The ones with surge protection are nothing but trouble, so if that's the case I would replace it with a non-protected one right away.