On 2/2/2011, Lauren Crane wrote:
I am in a discussion with a colleague asserting that EN/IEC 60335
provides
that a DC voltage up to 120V can be considered safe under dry conditions.
Since most other standards I deal with set the limit of safe DC at 60V, I
wonder if he has read a typo or if there are other conditions surrounding this
level.
I do not yet own a copy of 60335 but I know it has *many* parts. Can
anyone
say if 60335 concept of safe voltage is defined in part 1 or do different
appliance types get different treatment in this regard?
Hi Lauren:
I don't have a copy of 60335, but I know of two instances in EN 60950 where
voltages above 60 VDC are not considered hazardous voltages:
1) In a "Limited Current Circuit," voltages over 60 VDC are allowed but there
are strict limits on the available current.
2) In a TNV-2 or TNV-3 circuit (targeted at analog phone lines), DC voltages
up to 120 VDC are allowed, but there are some restrictions on accessibility.
Maybe one or both of these two classifications appears in some form within
60335.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
[email protected]
http://www.randolph-telecom.com <http://www.randolph-telecom.com/>
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