15A light switch on 20A circuit

[electricus]

It doesn't make sense to me to put a 15A light switch on a 20A ciruit, but I'm being challenged and can't find the exact information to back it up. I think it would make sense to just put the circuit on a 15A OCPD if 15A switches need/want to be used. So what is the correct answer for this, 15A switches on 15A circuit, have to use 20A rated switch on a 20A circuit?

There is another instance where there is a movable table with a hard wired light and light switch, it is cord and plug connected to the nearest hardwired (building) receptacle to were ever it is placed at the time. Is it allowable to have a 15A rated switch on the cord and plug connected table, even thought it may be plugged into a 20A circuit? If something like this is built how does one determine what the ampacity of the conductors and switch, if a 15A cord cap is used does this make the difference that now the whole this is "15A" rated. How does this compare to cord plug tools, like a shop vac for instance which might only have a 18/3 for the tool cord and it is plugged into a 15A or 20A circuit.

By the way all these examples are 120VAC.

 

[Dennis Alwon]

We install 15 amp receptacles on a 20 amp circuit all the time. The reason is that each outlet is not expected to carry 20 amps. The same with the switches. In the event that you had a load greater than 15 amps on the switch then you would need a 20 amp switch.

 

[electricus]

Correct we do install 15A Duplex receptacles all the time. A duplex is actually two receptacles, the code does state that if there are more than one receptacle on a 20A branch circuit then they can be 15A. This is the case if it is a single duplex (really two receptacles on the same yoke), or two or more single receptacles. But if there is only one single dedicated receptacle on a 20A circuit the code does state that it needs to be 20A. This was my understanding and interpretation, please correct me if I'm wrong.


I appreciate your response, but I was looking for a code article and not just "we do it all the time, so it is OK".

So in the instance I gave with the sight made table with a hard wired light and switch that is cord and plug connected. If I don't plan for it to have more than 15A on the light, hard wire, cord or plug, can I use a 15A cord cap, all 14 gauge wire, and a 15A switch? Would it be a good idea/required/needed to have onboard fusing for this table?

 

[Dennis Alwon]

So in the instance I gave with the sight made table with a hard wired light and switch that is cord and plug connected. If I don't plan for it to have more than 15A on the light, hard wire, cord or plug, can I use a 15A cord cap, all 14 gauge wire, and a 15A switch? Would it be a good idea/required/needed to have onboard fusing for this table?

Now you have given us something to work with. I cannot tell you a code article that permits this type of install. I can only tell you that there is no article that violates the install.

The NEC would not apply to a portable table or something that is not part of the structure of the building. Again I see nothing wrong with it. A lamp does not have to have a 20 amp cord when plugged into a 20 amp circuit. If this were a permanent structure then you will have an issue with using rubber cord as a fixed wiring method-- art. 400.8

 

[iwire]

404.14 Rating and Use of Snap Switches. Snap switches
shall be used within their ratings and as indicated in
404.14(A) through (E).

 

[roger]

There would be no reason to use a 20 amp switch to control a 60 watt lamp as Bob points out with the correct article section, the switch only needs to be rated for the load.

Roger

 

[dkidd]

We install 15 amp receptacles on a 20 amp circuit all the time.

That is specifically permitted by Table 210.21(B)(3).

 

[electricus]

I would understand that some stand alone home made or factory made equipment that is cord and plug connected can be smaller wire and rated for less that what the hard wired circuit is protected at. That part to me mostly makes sense (common sense).

A little variation of the subject, what about say a home that is wired. Lets say there is a 20A branch circuit with 12 awg that goes to a box with 1 or 2 light switches and they are 15A rated. Say each one controls a lighting load less that 15A each. What gauge does the wire need to be for the swtich leg (load side) of the light switch? I know what I would do based on common sense, but if this was a bid and someone was trying to find all the minimums of the code and do it cheap and by the book, what is the minimum?

 

[electricus]

Another idea, even though not needed, a piece of stand alone equipment could have a fuse between the cord and onboard ciruit, at least this way what is on the equipment would never be over loaded. What are the thoughts on this?

 

[infinity]

Lets say there is a 20A branch circuit with 12 awg that goes to a box with 1 or 2 light switches and they are 15A rated. Say each one controls a lighting load less that 15A each. What gauge does the wire need to be for the swtich leg (load side) of the light switch? I know what I would do based on common sense, but if this was a bid and someone was trying to find all the minimums of the code and do it cheap and by the book, what is the minimum?

The entire 20 amp circuit would need to be a minimum of #12 conductors. {240.4(D)}