The next proposed change for the tolerance levels adjusted to
10% the declared nominal voltage (IEE Regulation, Appendix 2:14).
The regulations are administered the Engineering Inspectorate the
Electricity Division the Department Energy and will not normally con-
cern the electrical contractor except that these regulations which lay
down the earthing requirement the electrical supply the meter position.
Thus the voltages used previously low-voltage supply systems 415V
and 240V have become 400V for three-phase supplies and 230V for single-
phase supplies.
The government agreed January 1995 that the electricity supplies in
the United Kingdom would harmonized with those the rest Europe.8
Basic Electrical Installation Work
These regulations impose requirements upon the regional electricity com-
panies regarding the installation and use electric lines and equipment.
FIGURE 1. The permitted tolerances the nominal voltage have also
been changed from 10% and 6%.
The frequency maintained average value 50Hz over 24h that
electric clocks remain accurate. This gives voltage range of
216–253V for nominal voltage 230V and 376–440V for nominal sup-
ply voltage 400V.
The regional electricity companies must declare the supply voltage and
maintain its value between prescribed limits tolerances.2
New health and safety law poster. Source: HSE Crown copyright material reproduced with the
permission the Controller HMSO and Her Majesty’s Stationery Office, Norwich.
