For many years, mainland Western Europe has used a mains electricity supply rated at nominally 220VAC 50Hz while the UK used 240VAC 50Hz.

In 1994, the European Union state members decided to proceed with a voltage harmonisation at 230Vac. This meant that consumers could be sure that a product bought in the UK would work in another EU country, and vice-versa (when used with the correct plug adaptor).

Since it wasn't economically viable to replace all existing grid switchgear to comply with the new 230V voltage level, the approach taken was to increase the tolerance of the supply in such way that will cover both existing 220Vac and 240Vac.

Regarding the LV Grid hardware, nothing immediately changed with the voltage harmonisation.

The new European tolerance values (230Vac +10% -6%) were chosen to cover all the existing supply voltages so any supply that was compliant before will be compliant after. However, across the years, as new grid switchgear is installed, the 230Vac nominal voltage is becoming more and more common.

Regarding the end devices, before the harmonisation, the products were designed to 220Vac and 240Vac depending on where the item was going to be sold. After the harmonization, manufacturers started designing end devices according to new 230Vac nominal voltage, but you can still find 220Vac and 240Vac devices aimed for other markets other than European.

Regarding the selection of products to be used in the UK, ideally it should have a nominal voltage of 230Vac. Due the historical reasons stated above, the 240Vac devices can be used with confidence.

Released for:Schneider Electric UK