I hit the send button too soon. I forgot to mention the standby symbol. I
added that below.
Rick, let's start with the general requirement per clause 1.7.8.1.
The requirement is "Unless it is obviously unnecessary, indicators, switches
and other controls affecting safety shall be identified or placed so as to
indicate clearly which function they control. Indications used for this
purpose shall, wherever practicable, be comprehensible without a knowledge
of languages, national standards, etc."
Does the switch in question affect safety? Since the switch performs
a power on/off function, I would say yes. Are the "on" and "off" positions
of the switch understandable without markings? Probably not, so some kind of
marking is required and the type is specified by clause 1.7.8. as the famous
"I" and "O" (or the push button symbol or standby symbol).
Is it allowed to mark a power switch that only switches one side of
the mains? Yes, the marking is permitted by clause 1.7.8.3 to be applied to
"any primary power switches."
Putting all of this together, the answer is yes, marking is both
permitted and required on your power switch.
But, do you use the "OFF" or the "standby" marking symbol? A main
disconnect device (breaks all poles and has 3 mm spacings) may use the "O".
All other types of on/off switches may use the "standby" marking since the
use of the "O" marking would be misleading to the service person and create
a potential hazard during servicing. This is your case since you cannot
guarantee that the unswitched pole will be an earthed neutral.
So, the short answer is that the "I" and "Standby" markings are
required for your product.
Richard Woods
----------
From: Rick Linford [SMTP:[email protected]]
Sent: Friday, April 27, 2001 12:25 PM
To: [email protected]
Subject: EN60950 (UL1950, IEC 60950) On off switch marking.
Hi All,
When a switch opens only one leg of the mains to control
power to
equipment should it be marked with the "l" and "O"?
Background:
Three different engineers from three different NRTLs
indicated it is
permitted, two even required it. A different engineer for
one of the
NRTLs and two other respected individuals indicate it is
prohibited. It
will be interesting if members of this list will have the
same 50/50
split or if there is a correct answer.
(single phase 100 to 240 VAC, 2A, 50-60 Hz, intended to be
shipped US,
Canada, EU and generally internationally)
To help, IEC 60950 (1999), section 1.7.8.3 Symbols, is shown
below.
Where symbols are used on or near controls, for example
switches, push
button, etc., to indicate "ON" "OFF" conditions, they shall
be the line
l for "ON" and the circle O for "OFF" (60417-1-IEC-5007 and
60417-1-IEC-5008). For push-push type switches the symbol
{line in side
the circle} shall be used (60417-1-IEC-5010).
It is permitted to use the symbols O and l to indicate the
"OFF" and
"ON" positions of any primary or secondary power switches,
including
isolating switches.
A "STAND-BY" condition shall be indicated by the symbol
{line breaking
the circle at the top} (60417-1-IEC-5009).
My bias was not included in the 50/50 statistics noted above
but I
believe it is required.
Rick Linford
Regulatory Engineer
SonicWALL
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