Does anyone know the range of mains voltage that suppliers are legally allowed to provide to domestic households in the UK ? Does it vary between suppliers ?

The reason I ask is that, over the last 18 months an unusual number of pieces of mains powered equipment, both new and old, have developed faults. Whilst I've suspected the "Made in Southern China" label may have a something to do with these failures, at least 50% of the failed kit has a date of manufacture which would seem to make this explanation unlikely. Also, the failing kit ranges from microwaves, radios to electronic toothbrushes.

As the home electrics are not that old (1985), I'm beginning to suspect the mains supply.

A voltage meter attached to my computer uninterruptable power supply was registering a voltage range, earlier on this afternoon (16.00), between 241 -247 volts - I wouldn't expect that this is due, in this area, to housewives putting on the sunday roast !

I know that under the 1993 EU/Cenelec harmonisation of electricity supplies the supply voltage was due to be set at 230 V.+10% - 6 %. I wonder if this has varied since then ?

Secondly, when powergen took over my supply two years ago, they replaced the analogue electricity meter with a digital one. If the electronics in the new meter is designed to deal with 230V as the midpoint supply voltage, then it is definitely being overdriven at 247 and could be giving an incorrect reading.

I also notice that the neon lamp in one of my trailing lead is flickering constantly - not a loose connection, I've checked. Is this a harmonic at work ? If so how could I find out where its coming from ?

If there are any sparks out there, I would appreciate a steer on this one.

Cheers !

Nick

29/10/06

That voltage sounds ok to me, right now my PC is being fed by 243 volts. The flickering neon, dont worry about it. All mine flicker, and had no issues with any equipment failure.

Your problem maybe surges in the supply caused by something local, dodgy fridge/freezer for example. To get a real handle on things you really need to monitor constantly with a device to log the fluctuations.

The harmonisation of mains voltages in EU countries was fudged, and as a result we had two slightly different "standards". Most of Europe (the former 220V countries) standardised on 230V -10% +6% (i.e. 207.0 V-243.8 V) while the UK (formerly 240V) standardised on 230V -6% +10% (i.e. 216.2 V - 253.0 V).

In practice, this means that kit designed for EU-wide use has to be rated at 230V -10% +10%.

The fudge was officially sanctioned when 230V plus/minus 10% was adopted as the new EU standard in 2003

To be honest most appliances are rated at 240v so 247 shouldn't really hurt them ....but get the supply people to do a check on the supply at the meter just to make sure....(could be a local transformer throwing a wobbly) best thing is to ask around the neighbors to see if they have had the same problems......if a lot have you may be able to claim compensation.....something similar happened near us when a supply contractor managed to put 415v down domestic lines while replacing the cables in the village...they had to replace quite a few things but it was a long fight

Plus, don't get confused about different suppliers giving you different electricity. It doesn't work like that, they are just brokers. It's all generated by the same places no matter who sends you a bill.

Frequency is more critical - may be worth a quick check if you have the gear. But i would very much suspect it not to be out.

The issue at the back of this query is that my average monthly household consumption, expressed in Kwh, has risen by 34% (55.95 Kwh per month) since the installation of a new digital meter in April 2004 - the meter is rated at 230V ! The only new equipment that has been installed since April 2004 is a masthead TV amplifier rated at 10W (Input) and mini dishwasher rated at 510w (3/4 hour cycle, 10 times a week). I reckon that's only contributing 22.5Kw a month or 40% of the total increase and the life style has not certainly changed - in fact I've been away from home more than ever the last 9 months ! So where's the rest of the increase coming from ? Going the other way, since 2004, I've substituted 9 of the most heavily used incandescent bulbs (Lounge, kitchen and bedroom) for low wattage flourescents.

All in all its a bit of a mystery.

I suppose that if there was a short of that amount of power, I would have seen the smoke by now !

Re Octygone's comment above. there has been a new housing development in my street which started to become occupied at the end of 2003, so there's a possibility there.

I still think its a dodgy meter. A missive is going off to Powergen this evening !

Frequency is more critical - may be worth a quick check if you have the gear. But i would very much suspect it not to be out.

I would be very surprised if frequency was much out at all. Think about what would happen if the grid lost synch?:eek: :eek:

I

I’ve heard that some of these digital meters use a surprising amount of electricity, almost as much as a small appliance left on standby. The old meters didn’t turn if there was no current flow hence no extra usage, but these new ones draw current all the time as they are microprocessor based.

Hmm. But don't they use unmetered power for use? In the same way that R-C timeswitches have two live feeds; one metered and one not.

And previous to my last post, I think hugely inductive loads could cause sync problems, but surely not much? And I'm not sure it'd be the electric board's problem even if they did.

It's normally 240v for mains...

Hmm. But don't they use unmetered power for use? In the same way that R-C timeswitches have two live feeds; one metered and one not.

I don

It's normally 240v for mains...

You seem to have missed Mike's (KLB) excellent explanation of harmonization above.

It might be another thing I read once, or perhaps it

You seem to have missed Mike's (KLB) excellent explanation of harmonization above.

I read it. Thanks...

You have to remember, that Voltage varies, not by much but needs space for expansion.

As said already, it's been measured at 247, So it's fine?

Frequency is more critical - may be worth a quick check if you have the gear. But i would very much suspect it not to be out.

for most aplliances in your house the mains oscillation frequency (50hz) is unimportant, most devices are fed though a rectifier bridge anyway so adjusting the frequency shouldn't have any effect......

the huge 3 phase dimming equipment we use in the theatre has built in reporting software which logs stuff like mains voltages, frequencies etc.... it is quite common for the mean voltage to vary by as 5 volts throughout the day depending on how much load is apllied to the local grid.

many years ago ,at Technical College ,when I was an apprentice ,I remember being told the frequency of the Mains was very accurate at 50 hertz, (cycles in those days) something to do with all the Generating Stations ,and a thing called Power Factor (whether the current lags or leads the voltage).Also meters are run from the unmetered supply ,at no cost to the Consumer.

I would be very surprised if frequency was much out at all. Think about what would happen if the grid lost synch?:eek: :eek:

Hence my closing staement

But yes, it would certainly be an interesting thing to watch if it lost synch

Yours mains is nominally 240V, 50Hz. It is well-regulated in the UK.

This is unlikely to be the problem.

More likely is that you have some equipment that presents a reactive load that is generating nosie spikes when it is switching on and off. This would most likely be an inductive load - something with big transformers or electric motors - check fridge, washing machines, central heating pumps, vac cleaner etc., the older it is, the worse it is likely to be.

Hence my closing staement

But yes, it would certainly be an interesting thing to watch if it lost synch

Im talking out of my depth here as a mech, but we do get quite a "lumpy" grid on the west coast of Scotland here, We have to run the grid through our own frequency changer's or supply our own from diesel alternators through our frequency changers as our [official secrets act] specialist equipment needs clean leccy[/official secrets act]

You seem to have missed Mike's (KLB) excellent explanation of harmonization above.

Er, I forgot to add...

Since the UK pre-harmonisation UK mains standard of 240V was held to very close tolerances, it actually complied with the 230V +/- 10% EU harmonised standard - so the electricity generating companies didn't actually change anything! In practice, UK mains are 240V +/- a couple of percent.