Major domestic electrical problem

[atticus999]

Hi - looking for some expert help please. I recently had the following problem. Water heater digital timer burnt out, fridge/freezer, extractor fan and cooker hood all blown and will not restart (fuses all checked). It's the second time the water timer has burnt out in a matter of weeks - and suspect this caused the other appliance problems. I have had 2 electricians in to test and advise - neither could find any problem with the circuits and had no idea what caused the appliances problem. 3rd digital timer now installed. Clearly I need to get to bottom of this as I can't afford it to happen again. (I'm not an electrician BTW). Any help / advice gratefully received. Thanks in advance.

 

[atticus999]

Hi - as there’s a good chance it’s a supply problem, maybe call your network operator (DNO) and ask for a safety check. Pop your postcode into this and it will give you a number to call.

Thanks - I will follow up on this

 

[atticus999]

How long have you been in the property?

Do you own or rent?

I own it - 5 years

 

[atticus999]

Strongly suspect broken neutral. Did you see lamps dimming etc prior to this? House built in1970s?

Lights on dimmer flash sometimes. Very old building but flat completely rewired 4 years ago.

 

[atticus999]

If the appliances are blowing due to too high a voltage (and this isn't the only thing that could cause it, but I'd say it's the most likely), this is probably one of three causes:

(1) Transient overvoltages of atmospheric origin transmitted by the supply distribution system, and switching overvoltages

(2) Incorrect supply voltage

(3) High resistance neutral joint between the star point of three phases (say, 3 adjoining houses, each on a different phase) and the incoming supply neutral.

.....

Many thanks for detailed reply. Where would I plug in a monitor? Would it keep a history of any surges or other problems? How would I get an SPD fitted? Thanks again.

 

[Pete999]

Many thanks for detailed reply. Where would I plug in a monitor? Would it keep a history of any surges or other problems? How would I get an SPD fitted? Thanks again.

Depends on the type of monitor, if the problem is giving you that much grief, I would ask your DNO to fit some monitoring equipment in your house, maybe they could fit it in the feeder pillar, or the sub station, having little or no experience of this type of thing, I can't be sure how they would do it.
The DNO will have access to this equipment, buying or hiring something that is unsuitable is a false economy. As for the SPD an Electrician will advise.

 

[happysteve]

The little plug-in jobbie, you can plug it in anywhere. It won't record what the voltage is over time, and probably won't even record a maximum. But you can plug it into any socket, where you have good line of sight to, and just see what happens to the voltage over time. It won't do anything more than what the electrician can do with their MFT - but the advantage is, it's there all the time, and the electrician is not.

As others have said, the voltage should be in the range 230V +10% / -6% (216.2V to 253V). Whilst the plug-in jobbie won't be callibrated, in practice they are likely to be accurate (I've just compared my £10 plug-in jobbie that I bought from Maplin 15 years ago with my calibrated MFT, and they match exactly). If you visually monitor the voltage over time (a few days) and notice it ever going above 253V, you have a little more to back you up when you phone the DNO.

When I had problems with my house, they fitted a little black box in the meter cabinet, tailed in to the supply meter, and left it there a week or two (while all around me stuff stopped working). I don't know whether or not these posher data logger type devices record transient surges or not - I suspect not.

Could you give us a bit more information about the setting? Are you in a rural area, with overhead supply lines, or a more urban setting? Do you know if you get your earth from an earth rod (which we would call a TT earthing system), or whether you get your earth from the supplier? If you're unsure, a photo of the service head (meter box) might help.

Also, have the losses of appliances coincided with any particular time of day, particular weather (bad weather/lightning) etc?

An SPD would ideally be fitted at the origin of the installation - an electrician might be able to fit one in your existing consumer unit, or in a separate enclosure next to it.

You can buy extension plugs/4-way adapters with SPDs in them from Wilkos/Tesco and the like - these will protect sensitive equipment plugged into them against surges, but not necessarily against sustained overvoltage or a broken neutral.

 

[James]

Uk power networks, London.

0800 029 4285
Give them a call on Monday,
Tell them that multiple lights are flashing and several appliances have blown.
They should send someone round to check it out swiftly.

 

[DPG]

Lights do sometimes flash on and off (suspected dimmer issue)

Points towards broken neutral issue rather than needing SPDs. Let us know what your supplier says or does.

 

[atticus999]

Could you give us a bit more information about the setting? Are you in a rural area, with overhead supply lines, or a more urban setting? Do you know if you get your earth from an earth rod (which we would call a TT earthing system), or whether you get your earth from the supplier? If you're unsure, a photo of the service head (meter box) might help.

Also, have the losses of appliances coincided with any particular time of day, particular weather (bad weather/lightning) etc?

It's (very) urban - so underground. Whatever caused the appliances to go all happened at the same time (apart from the digital water timer which looked like a slow burn - literally). On the circumstantial evidence it looks as though the timer burned out over a period of time and finally shorted - causing the problem with the other appliances. No idea how this could happen though.

 

[Wilko]

Hi - timers often cook “for some time” before finally expiring, but I think it’s unlikely to have caused the problems seen in the other appliances.

 

[atticus999]

Finally resolved. Turned out to be a loose connection on the negative cable supplying the building. Very difficult to trace and only discovered by a buzzing/ sparking noise from the corridor cabinet.

 

[telectrix]

thasnks for the update. good to know you got it sorted. was it DNO or landlord responsibility?

 

[DPG]

Finally resolved. Turned out to be a loose connection on the negative cable supplying the building. Very difficult to trace and only discovered by a buzzing/ sparking noise from the corridor cabinet.

Nice one, thanks for letting us know.

 

[Pete999]

Hi - looking for some expert help please. I recently had the following problem. Water heater digital timer burnt out, fridge/freezer, extractor fan and cooker hood all blown and will not restart (fuses all checked). It's the second time the water timer has burnt out in a matter of weeks - and suspect this caused the other appliance problems. I have had 2 electricians in to test and advise - neither could find any problem with the circuits and had no idea what caused the appliances problem. 3rd digital timer now installed. Clearly I need to get to bottom of this as I can't afford it to happen again. (I'm not an electrician BTW). Any help / advice gratefully received. Thanks in advance.

Where are you based some members may be close and offer to help you out. A picture of the CU Fuse board may help , not the innards leave the cover on, and point out what has tripped.

 

[DPG]

He's found it Pete. See post 26.