Can I switch a load of < 15A (say a baseboard heater) on 20A circuit
with a 15A rated switch or does the switch need to be rated at 20A
because that is the rating of the circuit?
Thank you for your time,
oh hell yeah
that's like saying, I used to put gas in a 15 gallon tank.. but my
fifteen gallon tank caught a hole in it.. but I have a 20 gallon tank..
do you think the 20 gallon tank will hold 15 gallons...
oh hell yeah
don't worry, you won't burn the house down
#2... if you were to say.. can I put a 20A rated appliance on a 15A
circuit I would be worried
I am sorry but I do not follow your logic. What I am saying is not
crazy. I have several lamps with 18 AWG cord plugged into 20A
circuits. Some of these lamp cords even have inline switches which
appear to be rated at only 6A ( Please see
http://dale-electric.com/detail.php?itemnumberp450-M ). I am hoping
to place a 15A switch on a 20A circuit to switch a fixed load < 15A.
The code may or may not allow it (which is what I am trying to
determine here) but the danger involved with such an installation is
certainly quite low even if it turns out it is now allowed.
I'm not sure I followed their logic. However, the Canadian Electrical
Code-2002 does state that you must be providing currect carrying
conductors that can handle the maximum possible load requirement
In your case since you have 15a breaker switch the total maximum
carrying capacity is 15a. This requires a 14AWG conductor.
Your question is a little confusing though. You say a "20A circuit"?
Is it your intent to carry a full 20amps? (I don't think it is as you
also mention "can I switch a load of <15A").
If you have a 15a requiring load, and a 15amp breaker, and at least
14AWG wiring you have nothing to do with 20 amps whatsoever. Mind you,
I don't profess to being an expert and generally always say call your
I don't understand the gas tank story either.
No, you can't use the 15a switch. If you have a 20a breaker, everything on
the circuit must be 20a. Either get a 20a switch or a 15a breaker.
It is probably one of the more trivial code violations; after all, what
would happen if you actually put 20a through the switch? But it is still a
404.14 Rating and Use of Snap Switches.
Snap switches shall be used within their ratings and as indicated in
404.14(A) through (D).
(A) Alternating Current General-Use Snap Switch. A form of general-use
snap switch suitable only for use on ac circuits for controlling the
(1) Resistive and inductive loads, including electric-discharge
lamps, not exceeding the ampere rating of the switch at the voltage
Don't mean to be argumentative...
Switches must be as large as their loads. Couldn't possibly disagree with
But isn't there a general rule that all components must be as large as the
breaker that protects them?
There is no contradiction between the two; just because the switch must be
as large as the load doesn't mean is shouldn't also be as large as the
breaker. Certainly the breaker will be at least as large as the load.
No. For example, the NEC explicitly permits the use of 15A receptacles on a
20A circuit. And, as we were discussing here, switches need to be rated only
for the loads they control, not the rest of the circuit.
Doug Miller (alphageek at milmac dot com)
You can plug a table lamp into a 20a circuit but you certainly could
not switch a 20a load with that little switch in the lamp holder.
Another example would be the 18 ga wiring in a light fixture which
could be on a 15 or 20a circuit. The load (a couple light bulbs)
controls the amount of current that flows in normal operation. They
only size the wire to deal with a short and an 18ga wire would sustain
a dead short until a 20a breaker could trip.
the circuit breaker protects the equiptment your feeding. it also
protects the wires supplying the power from being over loaded and
the breaker rating must not be greater than the wire rating.
the wire rating can be greater than the breaker rating.
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