UK supply voltage tolerance

Mark Rand wrote:
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Certainly the statement from any utility 'it couldn't happen' should be treated with contempt - they don't monitor each customer premises and we have had similar problems while the wires were overhead. I anticipate that it might happen again. At least once told they DID switch of the feed rather than giving a 'dangerous' answer, and I suspect any adviser who made that sort of statement should be retrained?

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I'll bet you get brownouts in Bradford.
John S.

On Thu, 4 Feb 2010 05:30:44 -0800 (PST), John S
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Could do with one in Downing Street...
Mark Rand RTFM

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Wikepedia explains it. See paragraph headed standardisation at http://en.wikipedia.org/wiki/Mains_electricity
It appears that no country had to change anything to implement HD 472 S1:1988 (see references 1 and 2 on Wikepedia page).
It appears to cost money to get a copy of the source documents.

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I distrust wiki nowadays, any old idiot can contribute, so it would appear!
I found this: For a transition period (1995-2008), countries that had previously used 220 V changed to a narrower asymmetric tolerance range of 230 V +6% ?10% and those (like the UK) that had previously used 240 V changed to 230 V +10% ?6%.
But what now? The transition period is over - too complicated for me to get brain ache over :-)
Julian.

Julian wrote:
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230V +/-10% (207-253) Before you complain to the leccy board. Measure the voltages at the meter otherwise they might fob you off saying it is your wiring at fault. I have heard stories of their reluctance to do anything even in an over voltage cases.
Are you neighbours affected too? Maybe some extra ammunition to your cause??
Good Luck
Bob

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Thanks, I have been measuring at the meter.
I have an (I think) 11Kv supply to the property and a transformer, that looks like it dates back to the 40's up a pole that supplies just me and the neighbour. I'm of the opinion that it's old, inefficient and no longer up to the job. But I'm far from expert on the matter!
Regards Julian.

Bob Minchin wrote:
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We had a poor supply until all of the overhead cables were moved underground, now the UPS's have a fairly stable 235V while previously they used to drop into 'buck mode' when everybody switched on their kettles down the road ;) So even dipping below 207V was acceptable to them as long as it was above when they measured it ...
If you can work out which end of the road your feed is coming from it may be possible to check a neighbor closer to the supply point. As a bad joint further up stream would cause a problem. THAT was one reason the EB gave up on our over head cables - they all needed replacing anyway so moving under ground made sense and they could switch people over as they went rather than having to shut the whole area down for a couple of days. Of cause we still get problems with lightning strikes as the step down transformer is on polls further up the chain :(

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The document you want is "The Electricity Safety, Quality and Continuity Regulations 2002" (http://www.opsi.gov.uk/si/si2002/uksi_20022665_en.pdf )
There has been updates since but only to update references from the 16th regs to the 17th regs.
From page 14
(3) For the purposes of this regulation, unless otherwise agreed in writing by those persons specified in paragraph (2), the permitted variations are— (a) a variation not exceeding 1 per cent above or below the declared frequency; (b) in the case of a low voltage supply, a variation not exceeding 10 per cent above or 6 per cent below the declared voltage at the declared frequency; (c) in the case of a high voltage supply operating at a voltage below 132,000 volts, a variation not exceeding 6 per cent above or below the declared voltage at the declared frequency; and (d) in the case of a high voltage supply operating at a voltage of 132,000 volts or above, a variation not exceeding 10 per cent above or below the declared voltage at the declared frequency.
note: low voltage =< 1000 v rms AC
mmmm, electricity suppliers...... Good luck
It is not uncommon at all to see lights dim / flouresants flash when heavy loads are switched on. Electric showers and banks of downlighters are particually good at that.
Also, the regs on volt drop within an installation have changed for the 17th edition. It used to be 4% (9.2v) max. it has changed to 5% (11.5v) for general circuits and 3% (6.9v) for lighting.
In the regs there is a general requirement to install under voltage protection (this includes temporary loss of supply) where it may cause harm (section 445), for example a motor overheating, or an item stopping and restarting unexpectedly. In practice all consumer goods will be tested and suitable devices inbedded within, such as a thermal fuse or an interlock on a food mixer preventing you from getting at the moving blade should it restart. So this requirement can be largely ignored, and could itself cause danger if not properly applied, such as having to reset a trip in the dark. I have only come across dedicated units on large industrial stuff, with no-volt releases (Motor starters) providing enough protection for smaller motors / items.
Graham

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Thanks the lot Graham for the reply, very helpful indeed.
Julian.