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#84430 - 03/30/03 01:15 PM light switch question  
BiggladAnt  Offline
Joined: Feb 2003
Posts: 13
Is it agianst NEC to use 15 amp snap switches for lights where the branch circiut is on a 20 amp breaker? I see this done all ther time and cant find an answer in the code book 2002.

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#84431 - 03/30/03 01:57 PM Re: light switch question  
russ m  Offline
Joined: Feb 2003
Posts: 169
I'm not sure myself, but general snap switches are rate either 15amp or 20amp right on the switch.
Unless there is some code for switches comparable to 210.21 for receptacles, like maybe 210.23 it could be a toss up. I think I would allow it depending on the load.


[This message has been edited by russ m (edited 03-30-2003).]

#84432 - 03/30/03 02:18 PM Re: light switch question  
iwire  Offline
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
2002 NEC 404.14 snap switches shall be used within their ratings.

If you look at the whole article, to me it seems they mean the load and not the circuit but I am not sure.

Bob Badger
Construction & Maintenance Electrician

#84433 - 03/31/03 04:55 PM Re: light switch question  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,864
Brick, NJ USA
IMHO, the switch rating is related to the connected load that the switch controls. Also, a good designer takes into consideration what type of "load" the switch controls. IMO, the resi guys use the 15 amp switches almost 100%. Comm guys tend to use the 20 amp rated. I can't remember having a call-back for a bad switch, as we install the 20's most of the time.
It's also a "spec" thing....if the prints/specs say "20 amp rated switches" then it's a no brainer.


#84434 - 03/31/03 07:11 PM Re: light switch question  
kale  Offline
Joined: Nov 2002
Posts: 174
If your OCD is 20A, I would not create a week point with a 15A switch. If your load is such that 15A is sufficient, I would change the OCD to 15A and put a 15A switch in.

#84435 - 03/31/03 08:10 PM Re: light switch question  
Bill Addiss  Offline
Joined: Oct 2000
Posts: 3,878
In my opinion the switch rating is related to the load as Bob (Iwire) and John (Hotline) had said. A typical Dimmer switch is rated at 600W and I've never seen a 5A circuit breaker.


#84436 - 04/02/03 12:37 AM Re: light switch question  
HotLine1  Offline

Joined: Apr 2002
Posts: 6,864
Brick, NJ USA
Quickly, what I mean is
20 amp branch circuit
Feeding lighting in 5 office rooms
Each office has 2 fixtures @ 3 amps total
Each Office gets a 15 amp switch (spec grade)
(or 20 amp isf engineer/arch has spec)
Load thru switch is 3 amps

20 amp branch circuit
Feeding lighting in one room
Lighting load is 15 amps
Switch is 20 amp (spec grade)

In the first example, we could OCP the circuit at 15 amps; but we run all 20's in comm, unless spec says otherwise.



#84437 - 04/02/03 10:01 AM Re: light switch question  
C-H  Offline
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Bill brought up Dimmer switches:

At least the European dimmers are always fused. I expect the American to be too. Unfused dimmers are allowed, but the safety requirements (oversizing) for these are so severe that the manufacturers don't make any.

A light switch is a different matter, since it isn't fused. However, as long as it can cope with the load and the short circuit current, there isn't a safety issue. Look at the ordinary switches on lamp cords or in table lamps. They a rated for only a few amps, but you are allowed to plug them into an ordinary socket. The only risk - which I'm sure doesn't exist of you follow the NEC - is a short circuit which doesn't trip the breaker instantly.

This of course doesn't answer the question if it is legal.

#84438 - 04/02/03 09:32 PM Re: light switch question  
ZackDitner  Offline
Joined: Oct 2002
Posts: 47
Kitchener, Ontario, Canada
I've never seen a dimmer switch that was fused (i'm assuming you mean either a fusable link on the wire, a resettable fuse on the device itself somehow, or well, i'm not sure), i just know that our dimmers in US & Canada have no overcurrent protection what so ever, if it's rated at 600watts and you pump 1000watts through it, it gets too hot and makes fire, or whatever else thats going to happen happens [Linked Image]

#84439 - 04/06/03 12:56 PM Re: light switch question  
C-H  Offline
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden

Yes, I meant a fuse in the the device. (Ranging from simple glass fuses, to self resetting overcurrent protection)

I'm surprised, considering the high level of electric safety otherwise aimed at by US and Canada. But, on the other hand, that ought to answer the original question: If it is legal to install a dimmer switch, a regular light switch must be legal too, right?

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