What is your mains voltage?

coffeehound

Here it seems to sit around 247 volts if a Maplin energy monitor and cheapie multimeter are to be believed. Sometimes it wanders over 250 volts. When I lived in the south-west, it would occasionally exceed 260 volts!

I was wondering about the effects of this. High voltages would certainly affect the power consumption of some items. I was sufficiently underoccupied earlier to test this by comparing a few appliances' apparent consumption to their rating plate using the Maplin power monitor:

Kettle rated at 2200 W | actual consumption 2500 W
Toaster rated at 1300 W | actual consumption 1520 W
Espresso m/c rated at 1100 W | actual heater consumption 1250 W

I suppose it's a complex picture as to whether an appliance will end up using more energy overall or not. E.g. the kettle will not use more energy, it'll just mean a shorter wait for tea.

Any other effects of this seldom mentioned situation? Which appliances will end up using more energy overall than the rating plate would suggest? I suppose an old filament lightbulb for one.

In any case, it seems safe to say you shouldn't trust an appliance's rating plate at face value.

Owain_Moneysaver

In fact, because the kettle boils the water more quickly, there will be less thermal loss over time, so in total it will use slightly less energy!

You also have to check whether the appliance rating is at 230V or 240V. For most things it doesn't matter, but if you're sizing a cable for a 10kW shower you need to be clear of the difference.

Gerry1

The nominal voltage is 240V and that's still the case now.

When the EU standardised its voltage at 230V, we just frigged our tolerances which are now +10% and -6%. So your voltage can happily wander down to 216.2V and up to 253V.

coffeehound

Owain_Moneysaver wrote: »

In fact, because the kettle boils the water more quickly, there will be less thermal loss over time, so in total it will use slightly less energy!

Heh, good point.

Owain_Moneysaver wrote: »

You also have to check whether the appliance rating is at 230V or 240V. For most things it doesn't matter, but if you're sizing a cable for a 10kW shower you need to be clear of the difference.

Interesting. So for something like a 3 kW immersion heater, that figure must be for 240V, otherwise if it was true for 230V it could end up tripping the breaker.

Gerry1 wrote: »

The nominal voltage is 240V and that's still the case now.

When the EU standardised its voltage at 230V, we just frigged our tolerances which are now +10% and -6%. So your voltage can happily wander down to 216.2V and up to 253V.

Thanks. Blimey that is a low figure at the bottom end. So where it went over 260V, that was definitely out of spec.

Owain_Moneysaver

coffeehound wrote: »

Interesting. So for something like a 3 kW immersion heater, that figure must be for 240V, otherwise if it was true for 230V it could end up tripping the breaker.

3kW at 230V is still only 13 Amp, and immersions would normally be on a 20A radial. Sometimes a 16A.

10.5kW shower is 45.65 at 230V and 43.75 at 240V. So at 230V a 45A circuit/switch is strictly speaking insufficient. Depending on mounting method the difference between 44A and 46A could mean the difference between 10mm and 16mm cable which is a big difference in cost.

AndyCF

Steady at 239VAC But its a very cheapy device I used, so I'd not really want to say how much tolerance that has for accuracy at a higher AC range!

Unfortunately the display for HV does not include tenths as its only got three digits so I can't give you a 239.x read. Not that it matters to be that accurate I suppose given the tolerance permitted.

Talking of which I was not aware of the specifics until Gerry1 kindly posted them) I'd assumed it was something like +/- 10% anyway so I guess I was not a million miles away!

Fractionally concerned about people " poking 'things' ! " into (lets be honest) potentially deadly voltage/current output sockets though! Volts jolt but mills kill etc etc. I hope those doing this are either being very sensible or using a plug-in 'measuring/testing' device. Having said that I think there's some plugin 'brick' thing a bit like those L/N reversed testers that just has an LCD output showing the voltage.

matelodave

Mine's usually around 247 to 248v but sometimes goes above 250, seldom below 246v.

Checked with a plug in Maplin power meter and a calibrated multimeter.

I'm guessing that most stuff is rated at 230v which is halfway between the European 220v standard and our old 240volts.

Carrot007

Gerry1 wrote: »

The nominal voltage is 240V and that's still the case now.

When the EU standardised its voltage at 230V, we just frigged our tolerances which are now +10% and -6%. So your voltage can happily wander down to 216.2V and up to 253V.

-10% + 6% surely to any sane person ;-)


Or 230 +-10% as the "standard" is.


Not sure of the adjusted values relating to 220 but there must be some!

Gerry1

Carrot007 wrote: »

-10% + 6% surely to any sane person ;-)

No, I'm not insane, thank you very much. In practice nothing changed, we stayed at 240V but the UK upper limit was frigged to 230V +10% to give sufficient headroom for the 240V to fluctuate. (A 230V +6% upper limit would have meant that a mere 4V increase would have breached the limit.)

The old 240V limits were +6% (254.4V) and -6% (225.6V) so the upper limit has barely changed. When demand threatened to exceed supply the voltage was reduced by 3% and then by another 3% if that wasn't enough.

Of course, this is all about to change. When the going gets tough, smart meters will be used to 'manage' the demand; anyone unlucky enough to have one will be the first to find out the hard way (when they're cold and dark but the neighbours remain warm and bright) that the euphemism means 'load shedding' !

coffeehound

So it looks like other regions have similar variations

Owain_Moneysaver wrote: »

3kW at 230V is still only 13 Amp, and immersions would normally be on a 20A radial. Sometimes a 16A.

10.5kW shower is 45.65 at 230V and 43.75 at 240V. So at 230V a 45A circuit/switch is strictly speaking insufficient. Depending on mounting method the difference between 44A and 46A could mean the difference between 10mm and 16mm cable which is a big difference in cost.

16mm cable? That's a metric shedload of copper! The worse scenario I was thinking of is where you have an appliance specified for 230V (or even 220V as I suspect the Italian espresso machine is) which is then connected to fruity UK mains?

The immersion heater was a bad example; I forgot they are fed by a 16A breaker So instead, e.g. a kitchen kettle bought on the continent that is 3 kW at 230V. Connect that to a UK socket with 254V from Gerry's spec and it will draw 14.4 amps. Whether that's actually enough to pop the 13A fuse I don't know, but it's certainly on the ragged edge and will presumably go eventually.

Similarly for your shower case: if it were rated 10.5 kW at 230V, then if fed 254V, it would draw over 50 amps

Another thing: would high voltage shorten the life of some consumers? E.g. those 50W halogen bulbs seem to have a rather short life of perhaps a few months . . could they really be designed for the 220V market? :think: Also, does the design of the light fittings take into account the extra heat produced?

.

AndyCF

Gerry1 wrote: »

No, I'm not insane, thank you very much. In practice nothing changed, we stayed at 240V but the UK upper limit was frigged to 230V +10% to give sufficient headroom for the 240V to fluctuate. (A 230V +6% upper limit would have meant that a mere 4V increase would have breached the limit.)

The old 240V limits were +6% (254.4V) and -6% (225.6V) so the upper limit has barely changed. When demand threatened to exceed supply the voltage was reduced by 3% and then by another 3% if that wasn't enough.

I'm aware from donkeys years back the older TV's as in early 80's one at least that I used to work with usually had both "over" and "under" voltage cut-outs for safety. The tolerances were quite reasonable though even then for said limits. I can't remember offhand what they were but it did vary between manufacturers.

Gerry1 wrote: »

Of course, this is all about to change. When the going gets tough, smart meters will be used to 'manage' the demand; anyone unlucky enough to have one will be the first to find out the hard way (when they're cold and dark but the neighbours remain warm and bright) that the euphemism means 'load shedding' !

This gentleman here had some thoughts on that matter No signal = no off. Unless as previously mentioned in another topic it comes down to needing a "keep alive" signal every x hours. That would not surprise me but the network is not reliable enough for that yet anyway. I think this is a treat for the next 10 or 20 years mind you.