I read in !emc-pstc that Rich Nute <[email protected]> wrote (in
<[email protected]>) about 'electric strength
test' on Fri, 23 Aug 2002:
>
>
>
>Hi John:
>
>
>>   True SELV ..... requires double or reinforced insulation from hazardous
>>   live parts/parts at hazardous voltages [different expressions used for
>>   the same things] and basic insulation from earth. '950 SELV' allows SELV
>>   circuits to be earthed (see 2.2.3.3 of IEC60950:1999 or EN60950:2000 or
>>   of IEC/EN 60950-1).
>
>Why does "True SELV" require basic insulation
>between SELV and earth?
>
>What is the hazardous voltage source, and what
>is the current path through the body if that 
>basic insulation should fail?
>
>This is a question that has bothered me for a
>number of years.
>
>
[AOL] Me too [/aol]

You would have to ask the people who originated SELV.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk 
Interested in professional sound reinforcement and distribution? Then go to 
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

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