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Andy Wade

wrote:

I heard that UK mains voltage was reduced to harmonise with Europe..
if true when did this happen and what is it..?

It was reduced on paper only:

- the old voltage was 240/415 V ±6% (226-254 V for single-phase)
- harmonised voltage is 230/400 V +10/-6% (216-253 V ditto)

The new tolerance was supposed to change to ±10% (207 V min.), but this
seems to have been indefinitely postponed.

The actual supply voltage has not been changed (no-one's gone around
adjusting taps on transformers) and the DNOs still work to 240/415 V
nominal, even when building new parts of their networks, AIUI. Filament
lamps for the UK market are still made for 240 V operation.

Nevertheless for wiring design purposes: voltage drop, fault current &
disconnection time calculations you should now use 230/400 V as the Uo/U
value.

I have a relay with a coil voltage of 220 to 230V 50-60Hz which
replaces an old one (240V/50Hz).

Anything with a rating which includes 230 V should be OK.

--
Andy