UK supply voltage tolerance

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?

...pah! 16mm 4 core - baby stuff 160 amps per phase three phase

pah! 120mm 4 core - baby stuff.

Mark.

Swank

AWEM

We are single phase. We have a single phase 11KV (I think it's 11KV) supply to a transformer mounted up a pole in the garden, this transformer supplies just me and the neighbour from its single phase output. I think the root cause of the problem is this antiquated transformer which almost certainly dates back to the days when national grid electrickery first found it's way out into the countryside.

I've never seen anything like 240 volts - chance would be a fine thing :-) I'll be contacting MANWEB on Monday morning to see what they say on the issue.

I don't think the board's cable from the transformer to the meter is much more than 6mm :-(

Regards Julian.

I'll bet you get brownouts in Bradford.

John S.

But your factory is about 10 times the size of my house, garden, neighbours house, their garden and the road inbetween!

Charles

Could do with one in Downing Street...

Mark Rand RTFM

The document you want is "The Electricity Safety, Quality and Continuity Regulations 2002"

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

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

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

Julian.