Electrical equipment has to be designed to accept a range of input voltages about its nominal design centre, but if the actual supply is higher than necessary for proper operation, the equipment will consume more power than needed, and  in many cases life is reduced - both increasing the cost of ownership. 
However, the stability of the UK supply mains has always been reasonably good, but is likely to degrade as competition and decreasing profitability forces generators to take capacity off-line and indeed to decommission power stations.

European Voltage Harmonisation
The United Kingdom for many years had a standardised supply voltage of 240V ±6% (415V for three-phase) whereas continental Europe had a nominal supply level of 220V (380V).  From 1 January 1995 the nominal voltage across Europe has been 'harmonised' at 230V/400V.
This is not a real change, since the former 240V countries, including the UK, have in the first stage of voltage harmonisation a tolerance of 230V -6% to +10% (i.e. 216.2 - 253V) as compared with the 'old' limits of 240V ±6% (i.e. 225.6 - 254.5V).  However, the former 220V countries (most of Continental Europe) have limits of 230V -10% to +6% (207 - 243.8V).

The Electricity Safety, Quality and Continuity Regulations 2002, which came into force on the 31st January 2003, replacing The Electricity Supply Regulations 1998, formally confirm the UK standardised supply voltage tolerances at 230V -6% to +10%.  DECC, the Department for Energy and Climate Change has confirmed that this remains the UK position but is currently (April 2010) under review for a possible change to 230V ±10% in 2011.

Plans to harmonise the whole of Europe to 230V ±10% (i.e. 207 - 253V), which were due to be applied from 1st January 2003, were first postponed until 1st January 2008 and are now postponed indefinitely pending a consensus between the various parties.  Despite this postponement, any equipment intended for use anywhere in Europe and carrying the 'CE' mark will have to be capable of working over this wide range.



CL DgreyL outline 4ptv2

The Claude Lyons Group
2 Tower House, Hoddesdon, Herts, EN11 8UR, England
Spares are obtainable from www.lyons-instruments.co.uk who are stockists of surplus Claude Lyons units and spares .

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Company registered in England No 222791
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UK Established Since 1918

The Claude Lyons Group was founded in the UK in 1918 and is still in private ownership. Since our early days we have been innovators in areas related to voltage and power control and more recently in energy saving and harmonic mitigation. Operating as a global exporter with many years experience we can justifiably call ourselves a world leader in the field of voltage stabilisers, power conditioning and uninterruptible power supplies (UPS)