Junction box in ceiling


Old 05-29-11, 12:26 PM
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 8
Junction box in ceiling

I am trying to replace a two-wire switch with an automated switch (Insteon), which requires a neutral. This is for a pair of kitchen downlights (Lightolier 1102 in a sheetrock ceiling). There is no neutral at the switch for the light circuit. There is an outlet in the same box as the switch, with a neutral, but it's on a different circuit, which is GFCI. I have two ideas.

1) Eliminate the existing switch, install a relay/dimmer in the ceiling next to the light, and control the circuit with an Insteon remote switch. I could install an Insteon 2475D relay/in-line dimmer in the ceiling to control the light. The downlight has a junction box built-in. Can I put the dimmer unit in that box, which would be a little tight. Instead, could I put another junction box near the dowlnlight, in the ceiling for the relay? I would attach it to a joist and it would be accessible through the downlight opening. I do not want to have a plate/box showing on the ceiling. Is this a safety/code problem?

-- or --

2) Replace the switch with the automated switch (Insteon 2476D), and use the GFCI circuit's neutral. This would be easy, but my understanding is that you are not supposed to cross over to another circuit's neutral line.

Do either of the ideas above seem safe and code compliant? Any other ideas? (Given the switch's location, it would be difficult to run another neutral line to the switch box.)

I appreciate any help with this.
Sponsored Links
Old 05-29-11, 06:36 PM
Join Date: Sep 2009
Location: Louisville KY
Posts: 571
Your first idea is the only one acceptable per NEC, the second one does not meet code! If you do the first one any junction box needs to remain accessible either from downstairs or from the attic. They are required to have covers but they cannot be buried inside walls behind sheetrock.
Old 05-29-11, 07:13 PM
pcboss's Avatar
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 14,594
You cannot share the neutral of other circuits.

I don't think the recessed fixtures JB would have enough room for a dimmer. The dimmer would not have any place to radiate heat either.

I don't see either option as a solution.
Old 05-30-11, 07:25 AM
CasualJoe's Avatar
Join Date: Jan 2010
Location: USA
Posts: 9,400
You cannot share the neutral of other circuits.
In addition, if you did share the neutral, you would probably trip the GFI on the other GFI protected circuit. And yes, it also is a code violation.
Old 05-30-11, 06:49 PM
Forum Topic Moderator
Join Date: Sep 2005
Location: USA
Posts: 4,259
The Insteon in-line dimmers are designed to fit into the recessed junction box. I haven't installed one of those specifically, so I can't say how tight the fit actually is.

A couple other code-compliant potential solutions (depending on your setup):
- Run a new 3-wire cable to the switch box. This may require a bit of drywall repair, but it may end up being the easiest solution.
- Run a new 3-wire cable to a hidden but accessible location. Maybe inside a nearby closet, pantry, or cabinets. The in-line dimmer would be installed here, still accessible, but out of visible range.

Good luck!
Old 06-01-11, 08:48 AM
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 8
Thank you all for your comments.

There is a lot of room in the ceiling and no insulation, so heat dissipation may be okay, and there is a heat triggered switch on the box. I will also consider a relay instead of dimmer, which I assume runs cooler. I'll give some more thought to running another 3-wire cable, but I am dealing with the kitchen in the middle of the house with a finished basement and second floor below and above. I don't have the Insteon in-line dimmer, so I will order one and get a better feel for how it fits in the box.
Old 06-17-11, 05:48 PM
Thread Starter
Join Date: Dec 2010
Location: USA
Posts: 8
In case anybody was curious, the Insteon in-line dimmer fit well into the existing junction box. Works well.
Old 06-17-11, 05:51 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,060
Thanks for letting us know.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes