I still have in my filing tray, the following statement which I received
from my electricity supply company :
"From 1 January 1995, the declared nominal voltage of your electricity
supply will change.
Existing declared nominal supply voltage and permitted variation
240V (225.6 - 254.4 V)" (= 240 +/- 6%)
"Nominal Supply Voltage and permitted variation from Jan 1 1995
230V (216.2 - 253 V)" (= 230 -6% +10%).
There is also the subtle statement "You will see that the existing
voltage range falls almost entirely within the new range".
What this meant, is that in order to comply with HD 472 S1, which
required that "the electricity supply authorities of countries having
240/415 V systems should bring the voltage within the range
230/400 V +10% -6%", the UK effectively did nothing, since, as
you will see above, the new declared voltage range almost falls
within the old declared voltage range.
IEC 60950 was changed to include the requirement that "if the rated
voltage is 230V ...the tolerance (in determining the most unfavourable
supply voltage for a test) shall not be less than +10% and - 10%",
particularly to take the new European declared voltage and
tolerance into account. As I recollect, the BSI committee (of which
I am a member) reluctantly agreed that a product which was "safe"
at 230V +10%, namely 253V, would probably still be safe at
240V +6%, namely 254.4V. We did note, however, that other
safety standards had not changed the tolerances on their test
voltages - but we were only responsible for IEC/EN 60950.
Digging around further, I have found the following : -
"BEAB Requirement No. 22", June 1995.
"Testing of products rated 230V only.
Requirement. When products are assessed for use in the UK,
and are marked 230V only, where the standard calls for a
factor greater than 1.0 of rated voltage or rated inpurt, the
tests shall be based on an assumed rated voltage of 240V.
Where appropriate, rated input shall be recalculated for
testing purposes."
"Information. At a meeting on 23 February 1995 the UK
Notified Bodies expressed to the DTI their concern that a
test to the standard of a product for the UK marked 230V only
would not adequately meet their obligation under the Low
Voltage Directive as implemented by the Electrical Equipment
(Safety) Regulations 1994, knowing that the product would be
connected to a supply centered on 240V. The DTI accepted
the decisions of the meeting as representing "good engineering
practice" concerning the testing for safety of products for the
UK market, and will so advise the European Commission. This
BEAB Requirement gives guidance to Test Laboratories
following that decision".
I have no knowledge of any later revisions of the above BEAB
document.
Regards,
John Crabb, Development Excellence (Product Safety) ,
NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2
3XX
E-Mail :john.cr...@scotland.ncr.com
Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus
6-341-2289.
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