240v or 230v ?

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Can someone please clarify for me; are UK electrics 240 Volt or 230 Volt?

Different websites seem to state different ratings.

Thanks
 
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both. officially its 230v (need you ask, its the eu again) but some places its still 240
 
thediynovice said:
Can someone please clarify for me; are UK electrics 240 Volt or 230 Volt?

Well there was a move a few years ago to harmonise European power supplies, and instead of 220 over there and 240 here, we all now have nominally 230V. But there are tolerances, and I think it's + or - 10% (someone will correct me if I'm wrong, I'm sure) so it can be from 207 to 253V and still be within the acceptable limits.

The effect is that the UK still actually supplies 240V (checking right now I have 240.5V but looking back at the UPS logs it's been down to 234 and up to 248 during the past month) and it all still works.

But for calculations, you should use 230V.

Cheers,

Howard
 
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For many years the supply voltage for single-phase supplies in the UK was 240V +/- 6%, giving a possible spread of voltage from 226V to 254 V. For three-phase supplies the voltage was 415 V +/- 6%, the spread being from 390 V to 440V. Most continental voltage levels have been 220/380V.

In 1988 an agreement was reached (CENELEC Harmonisation Document HD472)that voltage levels across Europe should be unified at 230V single phase and 400V three-phase with effect from January 1st, 1995. Those countries with a nominal voltage of 240V (like the UK) were obliged to move to 230V +10% -6%, and those on 220V moved to 230V +6% -10%.

It was proposed that on January 1st, 2003 the tolerance levels would be widened to ±10%, and then that was pushed back to 2005, and then in July 2001 the CENELEC Technical Board decided to continue with the existing tolerances until 2008.

In any event, the European-wide harmonisation is not being done by having common supply voltages, but by requiring manufacturers to make products which operate over a much wider range. Since the present supply voltages in the UK lie within the acceptable spread of values, Supply Companies are not intending to reduce their voltages in the near future. This is hardly surprising, because such action would immediately reduce the energy used by consumers (and the income of the Companies) by more than 8%, although when the system is under heavy load the generating companies happily take advantage of the lower limit.
 
this assumed reduction in demand from a lower voltage assumes most load is resistive and does not use a thermostat

if load has a thermostat then it will just run more of the time to achive the same amount of total heat

if a load has a SMPSU then its current draw will increase as the voltage decreases
 
plugwash said:
this assumed reduction in demand from a lower voltage assumes most load is resistive and does not use a thermostat

if load has a thermostat then it will just run more of the time to achive the same amount of total heat
Most loads are resistive, but your thermostat point is well made. The largest single device people have in their homes is an electric shower. Some are thermostatic, but with most of them you control the temperature by varying the flow rate. Lower voltage will translate to less energy used - people won't stay in the shower for longer. The next biggest load would be a cooker, and you're right, if you need your oven at 200° then you need it at 200°, and the element will click on more often. Similarly with the kettle, the toaster, the iron, the W/M heater - you've got a fixed amount of energy that you need to put in to get the water boiled, the bread toasted, the soleplate or wash water at the right temperature.

So showers & lights are about the only items which would use less overall.

if a load has a SMPSU then its current draw will increase as the voltage decreases
Not many big ones of those in the home...
 
HDRW said:
thediynovice said:
The effect is that the UK still actually supplies 240V (checking right now I have 240.5V but looking back at the UPS logs it's been down to 234 and up to 248 during the past month) and it all still works.

every time i check mine, its between 242 and 245
 
Thanks for the replies.

The reason I asked was that I have to replace my shower at home. I took out a 7KW shower and am replacing it with a 7KW shower (the same). However, the cabling used for the one I'm taking out is only 4mm, and is supplied on a 30A trip from the consumer unit.

I was just trying to work out if the cabling and fuse were big enough - although the old one worked fine for many many years.

The new shower states 240V = 7KW. 230V = 6.5KW.

So, will my 4mm cable and 30A fuse be ok?

Thanks again guys.
 
4mm is a bit weedy for 7Kw (30A), though just squeaks in, though if it runs though anything but well a ventilated free space it really should be changed for 6 or 10mm. (insulation and conduit ewtc all affect its ability to cool down.)
See the cable calculator on the www.tlc-direct.co.uk website, the length will also play a part, as you should factor in voltage drop.
In practice it will probalbly be OK, as you dont shower 24/7, but if it were me I'd upgrade the wiring to allow for a bit of margin, and extend the life of the connectors and cables.
 

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