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Posted By: George Little Switch Rating - 02/14/05 05:05 AM
If we have a separate circuit rated 20a - 120v, and a single receptacle controlled by a switch, does the switch need to be rated for 20a?
Posted By: gfretwell Re: Switch Rating - 02/14/05 06:13 AM
Yes
Posted By: iwire Re: Switch Rating - 02/14/05 11:46 AM
George L. you sure know what questions to ask. [Linked Image]

I agree with Greg, but the NEC IMO is not so clear.

2002 NEC. 404.14 in part states;

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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).

OK, shall be used within their ratings IMO requires us to use the rating of the branch circuit.

210.3 in part states;

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the ampere rating or setting of the specified overcurrent device shall determine the circuit rating.

Seems cut and dry so far but when we go back to 404.14(A) and (B) IMO it gets less clear.

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404.14(A) Alternating Current General-Use Snap Switch. A form of general-use snap switch suitable only for use on ac circuits for controlling the following:

(1)Resistive and inductive loads, including electric-discharge lamps, not exceeding the ampere rating of the switch at the voltage involved

(2)Tungsten-filament lamp loads not exceeding the ampere rating of the switch at 120 volts.

Why tells us the loads can not exceed the ratings of the switch if the switch must be rated at least as high as the branch circuit?

The code and common sense already require that the load can not exceed the circuit rating.

Bob
Posted By: gfretwell Re: Switch Rating - 02/14/05 05:04 PM
It is a winding road to get there but if you have a single receptacle on a 20a circuit it has to be a NEMA 5-20 and that encourages using a piece of equipment > 15a nominal so the switch controlling it should reflect that anticipated load.
That said I have seen regular 43 cent snap switches controlling 1hp 120v motor loads but I wouldn't want to bet on how long they will last.
Posted By: iwire Re: Switch Rating - 02/14/05 05:32 PM
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if you have a single receptacle on a 20a circuit it has to be a NEMA 5-20 and that encourages using a piece of equipment > 15a nominal so the switch controlling it should reflect that anticipated load.

I agree but it really does not say that about the switch very clearly. [Linked Image]
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