UK supply voltage tolerance

Sounds like the cabling to the workshop is too wimpy, resulting in a voltage drop from the original supply voltage when you draw heavy loads. Try measuring the supply voltage at your main fusebox under the same load conditions & see what that is like - if the voltage is good there, then its your cabling that is at fault, not the supply.

Regards, Tony

I'm ahead of you on that one, the workshop is supplied with 6mm SWA and I'm only loosing around 2 volts between dis board and workshop. Thanks for the reply but have you an answer to my initial question?

Julian.

Wikepedia explains it. See paragraph headed standardisation at

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.

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

I believe that the situation as far as the UK supply is concerned is that it is required to be 230 -6%/+10%, and for the rest of Europe it is 230 -10%/+6%. This was carefully chosen for minimum impact on the power generators and maximum impact on the equipment manufacturers while still pretending that we have EU harmonization.

So where the 230 -10%/+10% variant that you have seen comes from is that this is what equipment manufacturers potentially (sic) have to handle if they are building products for the EU market.

So if the supply voltage at the company fuse is dropping below that range (less than 216) then it is out of spec.

Regards, Tont

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.

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.

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 :(

It was dropping below 200V last Sunday evening when the wife was cooking the roast and I had about 6KW on in the workshop - I guess that they are allowed to let the voltage drop below tolerance for short periods due to heavy demand on the grid - a voltage recorder is the answer, so long as they do it FOC!

Julian.

Tony - I thought the +/-10% limit came in 1st Jan 2003 - but I stand to be corrected. My copy of the 16th Edition is pre 2003 and says it is 'due to change' on that date.

OK - I can correct my own statement ... The +/-10% change was postponed until 1st January 2008 - and then was postponed indefinitely ... So the lower limit IS 216V for the UK currently ;)

Yep...but as I said, if you are building product for the EU market then your products have to handle the full +-10%.

Regards, Tony.

Most of the power packs I'm using now do 95V up ;)

Good, so I've got 'em by the short and curlies it would appear.

One of the most noticeable problems with low voltage is my old ''buzz box'' stick welder which seems to make a habit of extinguishing the arc at random - my newer ''inverter'' style welder does not suffer this problem. The fluorescent light tubes often extinguish and then strike up again when I start equipment that takes a big initial surge of current like the big angle grinder.

Julian.

Probably switchers on the input, boosting up to 400V from which the switcher that creates the output is driven. A ruse to reduce the PF of the PSU, so that power is absorbed for most of the input 50Hz waveform, thus removing the nasty harmonic spikes caused by peak conduction of diodes that feed smoothing capacitors.

Are you single or three phase? if single phase, what are the neighbours on the other phases seeing (eg, general low voltage or one over loaded phase)?

What is the maximum voltage you ever get? If it's below 240, a tap change may be simple, if much above that, they may be reluctant.

6mm Pah! I've got 16mm 4 core SWA (still no 3ph though :)

Mark Rand RTFM

neighbours on the

phase)?

...pah! 16mm 4 core - baby stuff 160 amps per phase three phase wired in 120mm entering workshop (but the plonkers EDF have fed it with 6mm diam (28sq mm cross section) aluminium overhead - no doubt it'll melt some time soon!)

AWEM

My logic was that if I managed to use all 63A 3ph in my little shed, I wouldn't have a shed any more, I'd have a small mushroom cloud :-)

Mark Rand RTFM

I've seen about 150V on my supply on one occasion for a few hours and my neighbour has seen it some years prior to that. He took it up with the utility the first time and their response was it couldn't happen as they had things in place to prevent it due to the danger it could cause. I took a reading to verify and turned off things like the fridge, most bulbs glowed dimly, flourescents varied from dim to OK depending on type. I ended up watching TV in the dim light as it must have had a universal supply and was unphased.

Any ideas about the regs requiring cutoff of supply in low voltage conditions.