Separate 15A and 20A circuits on the same combo switch/outlet?

[ddonoho]

I used to work for an Electrician years ago and just passed my homeowners electrical exam in order to wire my new kitchen and addition. The kitchen counter will be open to a new sun room/living room so I need to install the counter top outlets and switches in the 4" backsplash... so it's a bit tight (can't fit a 2G box). Is there any reason why I can't use a combo switch/outlet in the following fashion: use the switch for the garbage disposal (15A circuit) and the outlet as part of a 20A small appliance circuit? I'd also like to use another combo with the switch controlling some pendant lights (15A lircuit) and, again the outlet being one of the 20A SA outlets. I can't seem to find anything in the 2008 code that addresses this... Thanks.

 

[Dennis Alwon]

I would strongly urge you not to use a switch receptacle combo. For one they would have to be on separate circuits and box fill can be an issue.

 

[mwm1752]

2 circuits on the same yoke would have to be simontaneously disconnected -- device for single recept would have to be 20a rated and gfi protected -- agree there may be a box fill problem & would not recommend --

 

[kwired]

As has been mentioned you need handle ties on the breakers supplying more than one circuit to a single yoke.

As far as box fill - that is why they make deeper boxes. Pick the lesser evil, cutting additional holes in the backsplash or using deeper boxes if needed. Cost of extra materials/special materials is likely still less than additional labor needed for extra holes in the backsplash.

 

[ddonoho]

Thanks for the replies.

I don't believe I'll have a box fill violation since I was planning on running just one 14 wire switch leg to the switch of the combo. So I'd have 4 12AWG conductors and 2 14AWG conductors in a 20.3 cu 1G plastic box. Here's my box fill calculation:

4 - 12 AWG (4 x 2.25 cu) = 9 cu
2 - 14 AWG (2 x 2 cu) = 4 cu
Grounds = 2.25 cu
Combo = 4.5 cu
--------------------------------------
Total = 19.75

And I assume it's not a problem to connect the 15A and 20A breakers together with handle ties. But if I'm reading the tea leaves correctly even though this may be technically feasible and within the code, it's probably bad practice/bush league?

 

[RLyons]

Can't the disposal and pendants be part of 2 appliance circuits? Place the disposal switch under the sink or batch feed disposal. There is no other place to put a pendant switch?
A

 

[ddonoho]

Can't the disposal and pendants be part of 2 appliance circuits? Place the disposal switch under the sink or batch feed disposal. There is no other place to put a pendant switch?
A

As far as I can tell neither the disposal nor the pendants can be part of the SA circuits:

"(2) No Other Outlets.​

The two or more small-appliance
branch circuits specified in 210.52(B)(1) shall have no
other outlets."

Not crazy about putting the GD switch under the sink, but thanks for the idea about the batch feed disposal. I may also consider an air switch. And it's possible I move the pendant switch to a wall... so I've got some options to mull over. Thanks again.​

 

[ActionDave]

As far as I can tell neither the disposal nor the pendants can be part of the SA circuits:

Correct.

I may also consider an air switch.

That's what I would recommend.

 

[mwm1752]

Seems like you need to consider 404.2(C) -- where is the grounded conductor for your 15A circuit with only 1- 14-2nm in your box?

 

[ddonoho]

Seems like you need to consider 404.2(C) -- where is the grounded conductor for your 15A circuit with only 1- 14-2nm in your box?

Thanks for pointing that out - I wasn't aware of the change. We still fall under the 2008 code. Nonetheless, I think I'll avoid the combos.

 

[edlee]

Thanks for the replies.

I don't believe I'll have a box fill violation since I was planning on running just one 14 wire switch leg to the switch of the combo. So I'd have 4 12AWG conductors and 2 14AWG conductors in a 20.3 cu 1G plastic box. Here's my box fill calculation:

4 - 12 AWG (4 x 2.25 cu) = 9 cu
2 - 14 AWG (2 x 2 cu) = 4 cu
Grounds = 2.25 cu
Combo = 4.5 cu
--------------------------------------
Total = 19.75

And I assume it's not a problem to connect the 15A and 20A breakers together with handle ties. But if I'm reading the tea leaves correctly even though this may be technically feasible and within the code, it's probably bad practice/bush league?

I would have thought offhand that this (a handle tie for 2 single pole breakers) was not allowed. I don't have a code reference and may look into it just for fun. Anybody else know?

 

[JDBrown]

I would have thought offhand that this (a handle tie for 2 single pole breakers) was not allowed. I don't have a code reference and may look into it just for fun. Anybody else know?

Doesn't seem like a problem to me:

210.4 Multiwire Branch Circuits.
(B) Disconnecting Means. Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.

You need a simultaneous disconnecting means. You don't necessarily need common trip (although it is allowed).

 

[kwired]

I would have thought offhand that this (a handle tie for 2 single pole breakers) was not allowed. I don't have a code reference and may look into it just for fun. Anybody else know?

Ask yourself what the purpose of a handle tie is if it can not be used to tie two single pole breakers together?