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J-Boxes in the Attic

MrSurly

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Joined
Jan 15, 2014
Messages
1,671
Location
East Texas
What is the common thought on using 4-square boxes (plastic, w/covers) in the accessible attic space?
What does code say or maybe what is common practice?
The project at hand is my (old) house and making some changes to a room's use. I'm adding outlets to current code and lighting, including a few can lights. Part of the room is existing wall that I will be fishing 12 NM-b vertically with no access for drilling studs in that wall. I will have 3 or four cables to join for outlets and in the interest of simplicity (avoiding box-stuffing) I want to utilize a four-square or similar. There are others in the attic already but I'd like to know you guy's opinions as the propriety of doing this.
 
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sberry

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Jun 18, 2005
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35,747
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Brethren, Michigan
It's done all the time. Sometimes there isn't any choice. I did a couple rewires a while back. The first was a ranch and I started the job thinking it would be partial and copied the old design, hound have redesigned and came all from the basement.
The second job was 2 story and no way to get between floors on a lot of it, had to come attic down.
 

nh_yota

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Mar 10, 2015
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4,077
Location
Seacoast New Hampshire
Rewired the upstairs of my old house that way. Ran new circuits up from the panel in the basement and dropped branches down the walls to each outlet in a star configuration.
 
OP
M

MrSurly

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Jan 15, 2014
Messages
1,671
Location
East Texas
Is it recommended to mount them at the joists or should they be mounted higher to be out of the insulation? (buncha blow-in up there).
 

Slowgsr

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Nov 14, 2014
Messages
610
Location
Southern ontario
I like this answer. I have some that I only found after digging in blowin insulation. Not fun

I recently did some work at a 1880s home, been rewired maybe 30 years ago. I changed all the plugs/switches up stairs, the existing wire was ok however every plug/switch/fixture only had 1 wire in it. I went in the attic, very walkable. Zero visible junction boxes, originally the house had no insulation, I guess all the junction boxes got covered. 🙍.

If they ever had an issue I wouldn't be digging.
 
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Bert_

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Dec 24, 2016
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9,771
Location
NW Iowa
If you can, avoid the junction box altogether. Run the wire in and back out of the outlet/etc. Sometimes it just isn't practical and you have to use a junction box. Keep it visible or make a mark that will stay visible.
 

oledude1952

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Jan 20, 2019
Messages
69
Location
KY
Could either make these out of caution/colored tape or just buy them to use to stick up out of the insulation at the JB's. Then use a magic marker to write on the flags " Junction Box" JMO
 
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Siegel1719

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Joined
Nov 12, 2014
Messages
75
Location
Farmington Hills, MI
Like others have said sometimes there is no reasonable alternative. Just keep it visible and accessible. I have done it and wrote on the insulation in the living space accessible junction box that there is an additional junction box in the attic. Just in case I ever forget or sell the house.
 

75gmck25

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Jul 21, 2014
Messages
1,328
Location
Alexandria, VA
I ran two 12/3 wires from my panel up to the attic, wired as an MWBC, and then used a junction box to break it out into four circuits in the attic. Two circuits were used for a bath heater/light/fan and the GFCI receptacle, and the other two were for additional bedroom receptacles.

I used the deepest 4" square metal junction boxes I could find, and located them high enough to stick above the insulation. I used a Sharpie to mark the top cover with the circuit #, and to show which wires were in/out for power. Its not very elegant looking to have the boxes sticking up, but its easy to figure out what goes where. I used metal boxes because they might get kicked or hit when moving something around in the attic.

Bruce
 

allinon72

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Joined
Jul 5, 2010
Messages
3,307
Location
Indianapolis
Have a few in my 40s era house. I simply put a 1x across the joists and mounted the boxes on that. Easily visible over the blown in insulation.
 
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