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[sevenlayermuddle]

So they need thicker conductors / better conductivity?

Depends on the definition of 'need'. 

The problem (for me) only happens once a year and that being Christmas Day, evidence is hard to gather.  As long as the supply company can say there is no evidence of a problem, their shareholders would be unlikely to support any major spend.

The other solution is, of course, for me to buy a new oven... one that is properly compatible with the  modern 230V nominal supply, vs the 240V when my oven was new.   

[Weaver]

> The other solution is, of course, for me to buy a new oven... one that is properly compatible with the modern 230V nominal supply, vs the 240V when my oven was new.

Shows you what I know, living in the past. I thought it was 240 V still. But what do I know.

[roseway]

In 1995 the UK nominal mains voltage specification was changed from 240V +/- 6% to 230V + 10% / - 6%. Nothing actually changed at the time because the new specification embodied the old one. It was for harmonisation across the EU, and nowadays new electrical equipment can supposedly be used in any EU country.

[sevenlayermuddle]

I thought that the new tolerances for the 230v supply were actually staged, becoming more relaxed and reducing the lower limit progressively in several steps, and resulting in a minimum voltage that is now significantly lower than it was in 1995?   Or so it said in a forum thread I found recently (Possibly an IEE forum).

I also seem to recall hearing a while ago that, counter-intuitively, the lower voltage actually presented a safety/fire hazard in some circumstances.  Not entitely sure, but I think it was along the lines that some appliances (ovens/fridges)  that fail to reach target temperature end up running continuously rather than cycling on/off, leading to premature wear.

[roseway]

You may be right, I haven't been following the details.

[sevenlayermuddle]

You may be right

Don't bank on it, odds (of me being right) seem little better than 50/50 these days.   

[BigBunny]

I thought that the new tolerances for the 230v supply were actually staged, becoming more relaxed and reducing the lower limit progressively in several steps, and resulting in a minimum voltage that is now significantly lower than it was in 1995?   Or so it said in a forum thread I found recently (Possibly an IEE forum).

I also seem to recall hearing a while ago that, counter-intuitively, the lower voltage actually presented a safety/fire hazard in some circumstances.  Not entitely sure, but I think it was along the lines that some appliances (ovens/fridges)  that fail to reach target temperature end up running continuously rather than cycling on/off, leading to premature wear.

That is correct and reading an article several months back elsewhere this was being discussed that there maybe issues with insulation, high amperages, etc.  The original voltages came from the generating stations and single phase from three phase generation that was 440 volt, 415 volt and 380 volt.   You used to see 250 volt stamped on items due to the 440 volt. 240 volt due to 415 volt, and 230 volt as 380 volt 3 phase.  In the UK I have seen even in recent years domestic voltages from 220 up to 252 volts.  When I was responsible for a plant install in Belfast in the 80's the site had all three voltages running as there were supply coming  from NI, GB, and Eire.  The last information I had was that other counties that had lower voltages were gradually coming up to 230 volts and therefore as stated earlier in thread equipment will be suitable for any EU country.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/293405/05-1410-electrical-supply-tolerances-and-appliance-safety.pdf

[aesmith]

I assume it is because we are in a rural area and at the very end of a line.

Are you supplied on 240V?    Our first house was supplied on 240 via overhead lines, and you could visibly see the lights dim when switching on the kettle or toaster.    I've not seen this in other houses where we've always had our own transformer served off 11kV.

[sevenlayermuddle]

Are you supplied on 240V?    Our first house was supplied on 240 via overhead lines, and you could visibly see the lights dim when switching on the kettle or toaster.    I've not seen this in other houses where we've always had our own transformer served off 11kV.

Being pedantic, it's nominally 230V these days.   More to the point, yes, we are fed from, and at the end of, overhead wires.  Not entirely sure whether its 3 phase or a single pair but either way these cables have some impedance.

I've just tried an experiment... with just normal stuff (fridge, a few light bulbs, a PC etc) the mains was sitting at 222.5V.   Then I switched on both ovens (it's a 'range'), the kettle and the toaster.  Voltage dropped to 216.5V. 

But 216V is actually OK,  everything still works.  The only time a real problem arises is as I say, on Christmas morning approaching dinner time, when the entire village has their toasters, kettles, and ovens on.  Then 210V is not infrequent, at which point the oven's heater element is no longer capable of a decent temperature for roast potatoes.   

re 'harmonisation' and 'compatibility'. When I do get around to buying a new oven I'll be able to buy one designed for Europe.   Yippee.   But it won't stop me being hacked off that I have to buy it in the first place, when the old one still works, if only it could get the mains voltage for which it was designed.   

[JGO]

Have you looked at an autotransformer ? If you use say a 12v 4 amp charger transformer you can get a 12v boost (or buck) and it will handle some 900 kva, 'cos the transformer core only handles the difference in power.

.

[sevenlayermuddle]

Have you looked at an autotransformer ? If you use say a 12v 4 amp charger transformer you can get a 12v boost (or buck) and it will handle some 900 kva, 'cos the transformer core only handles the difference in power.

Thanks for the suggestion I think, but it's a bit over my head.   Which is depressing and embarrassing as, in a drawer upstairs, I have a nicely rolled up degree certificate from many decades ago, asserting I once knew a thing or two about electronics and electrical engineering.  That was before a career misspent as a software 'engineer'.

But even if I could muster the memories of such technology, wouldn't any such activities go awry if the supply company suddenly presented me with the maximum permitted voltage, not minimum?

[Starman]

sevenlayermuddle, perhaps you should contact your DNO and state you are experiencing "low volts" and "flickering supply" it could just be a poor connection on the OHL - failing that request a voltage recorder is installed.

Although it maybe the tap changer needs adjusting at the transformer - the voltage recorder should determine that. At the secondary substation level the transformer does have to be isolated as they "offload" taps only. So this would involve a planned shutdown affecting at least that one transformer possibility others depending on the layout of the local HV network e.g remote transformers / switch fuses etc.

[sevenlayermuddle]

@starman, I am sure you are right.  Indeed it's a bit naughty of me to moan about it without having first asked them to investigate.

TBH the voltages I'm seeing even today surprised me, I hadn't realised it was near-borderline on just a normal Friday evening.   I may well make some effort to contact them, thanks for the link.

[Ronski]

I haven't managed to contact them yet, and am still seeing high voltages every night. Is the voltage recorder a simple plug in device?

[aesmith]

Being pedantic, it's nominally 230V these days.

I think is was still 240V when we were in that house, that was 1985.   However even today I suspect a lot of places still receive 240V, for example see the data plate on our transformerNominal, but what is it really?  Our transformer says 250V nominal (see picture) so even using the lower tap that's going to be 239V.  Or did they reduce the 11kV distribution voltage?   Ours measured 239V just now, but I don't have a true RMS meter so that might not be accurate.  I had understood that the issue was fudged by allowing sufficient tolerance so that staying at 240V would still be within tolerance for the EU standard of 230V +??%



I'll have to have a look and see what taps it actually uses.