is 15A switch on 20A circuit safe?

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Old 09-13-15, 07:18 PM
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is 15A switch on 20A circuit safe?

Tried to buy 20A switches today for my new bathroom fan and lights, but there weren't any. Does NEC really allow me to use a 15A switch? Is that safe? Suppose somebody put a nail through the wire. Wouldn't the switch fail before the breaker tripped?
 
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Old 09-13-15, 07:22 PM
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A 15 amp switch is fine. Rarely are you switching a 20 amp load, if ever in a house.

A nail thru the wire may create a short and trip the breaker.
 
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Old 09-13-15, 07:27 PM
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Does NEC really allow me to use a 15A switch?
Yes.
Suppose somebody put a nail through the wire. Wouldn't the switch fail before the breaker tripped?
Probably not but even if it did no harm. Switch rating is based on the expected load. If you hooked it a load that actually exceeded 15 amps then the contacts might have a shorter life but no real consequences except a failed switch. In reality lighting load will be far less then it is rated for in most cases than 15 amps.

There is also a large "fudge" factor built into the switch design.
 
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Old 09-13-15, 07:56 PM
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Thanks! That makes sense.
 
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Old 09-14-15, 11:21 AM
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In reality lighting load will be far less then it is rated for in most cases than 15 amps.
That is also why it used to be allowed and was quite common to run 14-2 switchlegs on a residential 20 amp circuit.
 
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