Hi Rick:
There are three issues which we must address:
1. The safety function of the switch.
2. The safety function of all-pole disconnect
versus one-pole disconnect.
3. The marking of the function of the switch.
*****
The safety function of a disconnect device (for
which a switch is acceptable) is:
* to disconnect power in the event of some
sort of safety incident within the
equipment;
* to disconnect power for the situation of
servicing the equipment.
For cord-connected equipment, I alway designate
the plug or appliance coupler as the disconnect
device. This means that the power switch is not
an isolating switch. This solves the problem of
one-pole versus all-pole switch requirements, and
contact separation requirements.
For the first function, a one-pole switch will
satisfy all safety incident situations except
(50-50 chance) phase-to-ground fault (in which
case the building overcurrent devices provides
the protection).
For the second function, a one-pole switch
satisfies the servicing situation for a
polarized supply system with a polarized plug
and socket. A one-pole switch does not satisfy
the servicing situation for a non-polarized
supply system. (However, the plug does satisfy
the servicing situation.)
In the situation you describe, you can designate
the plug (or appliance coupler) as the disconnect
device, and the on-off switch as a functional
(i.e. not a safety) switch.
According to the requirements you quoted, the "0"
and "1" symbols may be used on *any* primary power
switch. So, the symbols may be used on either a
functional switch or an isolating switch.
For marking, there is no requirement that the "0"
and "1" symbols are restricted to isolating
switches. However, isolating switches must be
marked with the "0" and "1" symbols.
Most of our products do not have a primary power
switch. We use a secondary circuit functional
on-off switch. Since we do not switch primary
power, we do not use the "0" symbol, but the
"stand-by" symbol.
Best regards,
Rich
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