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.

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.

Russ

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

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.

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.
John

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.

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.

Bill

Kale:
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.

John

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.

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

Zack,

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?

Better visit England Bill! Lighting circuits in domestic work are alsmost always 5 or 6A.

I've never seen a normal domestic British dimmer which incorporates fuse protection of its own. Small units are typically rated 250W, and although 5 or 6A circuits are the norm, regulations allow normal lighting outlets to be run on anything up to a 16A branch.

P.S. That's 16A at 240V remember.


[This message has been edited by pauluk (edited 04-07-2003).]

Now Paul ....

I'll clarify. Never saw a 5A circuit breaker used as an OCPD in a Panelboard in the US
Better?

You know I've never seen one anywhere else either.

Bill

Bill:
"Small" amperage CB's are used in some control panels. There may still be some listed in the WWGrainger catalog, I haven't looked lately.

John

Ok, I give!!

I've seen them too used in pieces of individual equipment, but not in a typical residential load center to protect a standard 14 AWG lighting circuit that has 500w or 600w dimmers installed on it.

'Tough room' here sometimes ...


Bill

This thread has morphed into somthing new, so I'll throw this in
I've seen those modules also. I think their only rated as supplemental protection, and are not aproved for branch circuit protection.

Russ

Threadjack:

The British made MK dimmer switches work like this: (From product sheet)

Approximate load on the Dimmer as a percentage of its maximum rating

Up to 125: Load will receive maximum power continuously.

>125 to 150: Output to load will be reduced to 50% of the maximum after a delay of approximately 20 seconds after switch on.

>150 to 200: Output to load will be reduced to the minimum setting of the dimmer after a delay of approximately 20 seconds after switch on.

>200: Output will be disabled (load will be switched off) almost instantaneously after switch on.
------------------

Oh, just in case someone was wondering;
the requirements for dimmers are found in IEC 60669-2-1: Switches for household and similar fixed electrical installations - Part 2-1: Particular requirements - Electronic switches
(Fourth edition, Sept. 2002)

If they sell fifty of them, they'd probably call the title a bestseller.

[This message has been edited by C-H (edited 04-08-2003).]

I follow a simple rule: Nothing under-rates the breaker. 20A Breaker=20A switches=20A outlets=#12 wire or better. I know this rule isn't always adheared to by everybody, but why take a chance when the risk is a fire? On a residential lighting circuit that specs 15A switches, I use a 15A breaker with #14 or better wire. Period. YOu won't be tagged for doing it right...

Zapped,
Does that mean you use 1800 watt dimmers on 15 amp breakers and 2400 watt dimmers on 20 amp circuits?

I have a few 5 amp breakers. Made by GE.
I can't read the catalog number on it, but
the breaker is physically the same as a
40 amp GE breaker Catalog number TQC1140.

I also have a Federal Pacific 10A breaker
(not stablok).