Quick Question - Dodgy Electrics?

Tester46

I live in a house in a rural area. It has just been renovated and totally rewired. There are still some snags (circuits tripping when I put in a plug in some sockets, switch on certain lights, etc) which my electrician says he is resolving.

My question is: When I turn on any appliance (hoover, washing machine, power tool, sometimes the TV) the lights dip for an instant. In otherwords,there is a very fast mini-brown out. It is not a problem for me, but I just want to check is it normal or is it indicative of another problem with the wiring?

P.S. My electrician says it's totally normal, but as you may have guessed, I don't trust him 100%;)

davelerave

You need to measure the supply 'voltage drop ' at the mains to see if it's within tolerances (i think it's +/- 5%).
The max voltage drop within an installation is 4% but that wouldn't normally be an issue.
You can have problems on a re-wire when fitting an rcd for the first time but problems should be easy enough to resolve.

Tester46

davelerave wrote: »

You need to measure the supply 'voltage drop ' at the mains to see if it's within tolerances (i think it's +/- 5%).
The max voltage drop within an installation is 4% but that wouldn't normally be an issue.
You can have problems on a re-wire when fitting an rcd for the first time but problems should be easy enough to resolve.

Thanks for your reply davelerave.

Are you saying that there might be an issue (and one that is hopefully easy to resolve)? I don't want to even raise this with my electrician if it is absolutely normal and we should just leave it as it is like he says (he's not particularly open to criticism). If it is not absolutely normal and it is an issue which should be fixed, then I will raise it with him.

2011

Either it is a bad connection (easy to fix but important to fix!) or there is an issue with your ESB supply. I would guess that the later is your problem. I say this because it is often the case in rural areas. Either way you need to get it resolved. Voltage dips can cause damage to electronics.

I would ring ESB Networks if I were you.

davelerave

if you switch on an appliance and the lights dip,it's prob a voltage drop on supply side(excluding fusebox problems).
As 2011 said if it's a problem contact ESB networks .I normally measure voltage drop at main switch but only a recorder will give a complete picture .

Davy

Probably is esb networks problem on the voltage drop. Not much you can check apart from voltage after your meter. The 4% drop allowed is internal from your side of the meter. Before the meter the voltage range from the esb network should be 207v to 253 volts which is 230v plus or minus 10%.

They can fit a voltage recorder to monitor the voltage, once you haven't been using full load. They can check for current on the neutral/earth when they pull the fuse.

The internal tripping is a problem that your electrician has to fix, thats not an esb issue.

Jonathan

Speaking of brownouts, my housing estate had a brownout for about a half hour at the weekend. The voltage was only 117V.

Random houses along the road and scattered street lights were still working so I assume one of the the three phases was still operating ok.

I would have assumed that the ESB would be aware of brownouts on their network? They were unaware when I rang them to inform them.

Davy

Jonathan wrote: »

Speaking of brownouts, my housing estate had a brownout for about a half hour at the weekend. The voltage was only 117V.

Random houses along the road and scattered street lights were still working so I assume one of the the three phases was still operating ok.

I would have assumed that the ESB would be aware of brownouts on their network? They were unaware when I rang them to inform them.

They wouldn't know until someone rang in complaining of problems. That often happens where people automatically assume others rang, i would always ring so they know your mprn has problems. It can help them find it quicker, especially when its a cable fault


Edit: Forgot to say its only 38kv or above that is monitored really, so they wouldn't know about voltage problems on the Lv network

Jonathan

Any idea what could cause 2 of the 3 phases to drop voltage but the third work fine?

Rev. BlueJeans

Jonathan wrote: »

Speaking of brownouts, my housing estate had a brownout for about a half hour at the weekend. The voltage was only 117V.

Random houses along the road and scattered street lights were still working so I assume one of the the three phases was still operating ok.

I would have assumed that the ESB would be aware of brownouts on their network? They were unaware when I rang them to inform them.

Until the smart metering rolls out in a big way (residents in a certain part of Cork, and a West Cork village are the main recipients in the very short term during the next phase of the ongoing pilots) LV voltage monitoring is pretty much non existent. MV voltage can be quantified in specific areas, but only by polling certain switches and repeaters. It's not done unless necessary.

Basically, the reliance is on the customer to phone in. Undervoltage can cause many problems. Sounds like an MV fault in your case tbh, and if you were prompt phoning it in, they may have been unaware.

Just in relation to the OP, the voltage tolerance is 10% either way, so 207, to 253. However these are extremes.

First things first, was your meter relocated or your tails changed?

Secondly, are there others fed from your transformer and are you far from it (this one's easy, just go outside and follow the line).

If all else fails, you can log a voltage complaint, and ESBN will fit a voltage recorder and monitor your supply at the meter for a week or so, if there's no obvious issue, should give a fair indication if necessary.

Rev. BlueJeans

Jonathan wrote: »

Any idea what could cause 2 of the 3 phases to drop voltage but the third work fine?

Loss of a phase at MV.

Curtis E Bear

I agree with rev.bluejeans. And by the way nearly all MV feeders at 10kv and 20 kv are remotely monitored by the SCADA system. also not so sure this smart metering will roll out "in a big way".

Davy

Jonathan wrote: »

Any idea what could cause 2 of the 3 phases to drop voltage but the third work fine?

Most likely fuses in the near by sub.

Davy

Curtis E Bear wrote: »

I agree with rev.bluejeans. And by the way nearly all MV feeders at 10kv and 20 kv are remotely monitored by the SCADA system. also not so sure this smart metering will roll out "in a big way".

But they still wouldn't know what sub on the circuit caused the problem if it tripped or whatever, just that the one breaker in the hv station has tripped or going high.

Rev. BlueJeans

Curtis E Bear wrote: »

I agree with rev.bluejeans. And by the way nearly all MV feeders at 10kv and 20 kv are remotely monitored by the SCADA system. also not so sure this smart metering will roll out "in a big way".

It will, trust me

May take a couple of years though.

Curtis E Bear

My question is: When I turn on any appliance (hoover, washing machine, power tool, sometimes the TV) the lights dip for an instant. In otherwords,there is a very fast mini-brown out. It is not a problem for me, but I just want to check is it normal or is it indicative of another problem with the wiring?

Sorry i forgot to add, if the dip is only for an instant then it is probaly normal and is more than likly caused by the distance and type/size of conductor from the supply transformer.
A quick dip in the lights is not a brown out.:)

Rev. BlueJeans

Davy wrote: »

But they still wouldn't know what sub on the circuit caused the problem if it tripped or whatever, just that the one breaker in the hv station has tripped or going high.

In general, subs don't trip as such. Ground mounted ones will pop (usually two) MV fuses and trip out altogether mechanically. A short on the LV side will bring this one quite easily, but that will cause a no supply fault on anyone off that sub.

Pole mounted laddies have internal fusing, which isn't serviceable locally as such, it's easier to change the sub, not a major job in itself, but takes a bit of fault hunting at times.

Line down, a faulty pole mounted sub whose own line fuse(s) didn't drop in time, or faulty lightning arrestors,cables etc. again at MV, will often drop a line fuse, resulting in three phase customers being down two phases (actually, one will drop to zero, and the other will exhibit low voltage-like the gentleman above).

Single phase customers on single phase MV spurs will just lose supply of course.

LV fuses most commonly pop under load, in which case one phase goes down, or third party damage, in which case two or all may indeed go on that particular leg.

I haven't covered all possibilities in the above, but these are the most common scenarios.

Rev. BlueJeans

See my post above, Mr. Bear.

Doesn't sound like a domestic issue, but as I say if the tails weren't changed or the meter relocated (tbh your domestic faults nuisance trips etc. seem somewhat haphazard-and make me wonder if your leccie isn't quite finished!) then that should be sorted first.

The reason I ask if the meter was shifted is that the incoming tails and supply should generally be up to scratch. If it wasn't/didn't need to be, and your existing ones weren't large enough, then that in itself wouldn't help your problem.