two circuits in one box ?

handifoot · 05-22-2006, 02:45 PM

In my 50 year old home I have some boxes that have more than one circiut in them. Is this OK? I was planning to put my small appliance plugin combined with a switch for under cabinet lights ganged in the same box, (different circuits),please advise. Thanks.

IvoryRing · 05-22-2006, 03:32 PM

Assuming you mean the switchbox behind the receptacle... as long as it is big enough, this is fine. What's 'big enough'?

If you mean "replace a single gang box that has a duplex outlet with a new double gang box with an outlet and a switch", then you won't likely have a problem with 'box fill'.

If you mean "replace a duplex outlet with a combo switch/recepacle", AND your box is already tightly crowded, then you could easily have a problem with both physically getting the wires all back in and a thing known as 'box fill'.

If you have too many wires in a small space you are likely to have a problem with pinching the wires, either damaging them or the insulation, which can show up immediately or sometime later down the line. Also, if you cram too many wires in too small a space, then those wires can overheat when you are using both the outlet and the lights.

geeyathink · 05-27-2006, 02:41 AM

Also, it is not a code violation to have two seperate circuits in one box, if that was part of your question. There are some limits but what you describe is ok as far as two different circuits goes. You do still have to worry about Box Fill Calculations however.

jwhite · 05-27-2006, 01:14 PM

if there will be two seperate circuits on the same yoke. over and under eachother on a single gang. then the breakers have to be handle tied to meet code. this means the breakers have to be next to eachother.

05-22-2006, 02:45 PM	#1
handifoot Member Join Date: Feb 2006 Location: portland, OR Posts: 151	two circuits in one box ? In my 50 year old home I have some boxes that have more than one circiut in them. Is this OK? I was planning to put my small appliance plugin combined with a switch for under cabinet lights ganged in the same box, (different circuits),please advise. Thanks.

05-22-2006, 03:32 PM	#2
IvoryRing Member Join Date: Mar 2006 Location: New Hampshire Posts: 54	two circuits in one box ? Assuming you mean the switchbox behind the receptacle... as long as it is big enough, this is fine. What's 'big enough'? If you mean "replace a single gang box that has a duplex outlet with a new double gang box with an outlet and a switch", then you won't likely have a problem with 'box fill'. If you mean "replace a duplex outlet with a combo switch/recepacle", AND your box is already tightly crowded, then you could easily have a problem with both physically getting the wires all back in and a thing known as 'box fill'. If you have too many wires in a small space you are likely to have a problem with pinching the wires, either damaging them or the insulation, which can show up immediately or sometime later down the line. Also, if you cram too many wires in too small a space, then those wires can overheat when you are using both the outlet and the lights.

05-27-2006, 02:41 AM	#3
geeyathink Newbie Join Date: May 2006 Posts: 19	two circuits in one box ? Also, it is not a code violation to have two seperate circuits in one box, if that was part of your question. There are some limits but what you describe is ok as far as two different circuits goes. You do still have to worry about Box Fill Calculations however. Last edited by geeyathink; 05-27-2006 at 02:51 AM.

05-27-2006, 01:14 PM	#4
jwhite Member Join Date: Mar 2006 Posts: 682	two circuits in one box ? if there will be two seperate circuits on the same yoke. over and under eachother on a single gang. then the breakers have to be handle tied to meet code. this means the breakers have to be next to eachother.

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two circuits in one box ?