# Mounting junction boxes in attic, are both of these locations acceptable?



## diymonkey (Jun 23, 2007)

I need to mount some junction boxes in my attic for some new wiring. Most junction boxes that I have seen are mounted on the wide face of a joist (location #2 on the image below) but is it acceptable to mount the junction box on "top" of the joist (location #1 on image below) ?

NOTE: This is not a picture of my attic, just a picture i found on google to doodle on.


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## Bob Mariani (Dec 1, 2008)

Yes they are. JB's need to be accessible. This means that you can access them without removing any of the building's structure.


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## Rivethead (Dec 26, 2008)

Bob is correct - they are both acceptable. But, I'd side mount to keep the wires and box below the top of the joists as the wiring is currently run. Note the plates being used to protect the current wiring where it passes theough a joist.


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## DangerMouse (Jul 17, 2008)

but... wouldn't mounting on top make yer wiring job much easier?

DM


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## Bob Mariani (Dec 1, 2008)

DangerMouse said:


> but... wouldn't mounting on top make yer wiring job much easier?
> 
> DM


You mean keep the wires on top? This only makes house fires easier. Easy is not the determining factor in working with electric... safety is!


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## DangerMouse (Jul 17, 2008)

A: as to jb's, it's ok either way...
B: i'd certainly NOT be worried about fires if the box is on top and wired correctly.
C: the question is about BOXES, not WIRES!
D: if it were me, i'd put the boxes on top simply for the fact if i needed to do anything, the box would not be below the insulation.
no-one said anything about running the wires along the tops of the joists....

DM


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## dSilanskas (Mar 23, 2008)

Come on ladies can't we all just get along:laughing:


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## Bob Mariani (Dec 1, 2008)

yeah take it easy here. We are not attacking anyone, just making it as clear as possible. When mounting on top, it is easy to secure wires not on top of the joists. If you do have wires on top nail a 2 X4 cleat next to them, so they are protected.


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## Silk (Feb 8, 2008)

Bob Mariani said:


> If you do have wires on top nail a 2 X4 cleat next to them, so they are protected.


 
Not a code requirement most of the time. It depends on the distance from the scuttle hole and if you have a permanent ladder or stairs to access the attic. If not it is a waste of time and money.


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## Thurman (Feb 9, 2009)

Maybe it's a local code thing, but around here I've never seen the junction boxes in an attic mounted on the side(s) of a ceiling joist. The are always mounted on the top of the joist with the wiring run on the side, some type of securing device (usually a wire staple) securing the wires within twelve inches (12") of the box and per code here-a cover always on the box. That's why it's important to follow NEC and check local codes. Thanks, David


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## rgsgww (Jul 5, 2008)

No way I can do that in mine, like 1.5-2 ft of insulation. Boxes are on top, wires stapled within 12 in of box. Currently I'm fixing some bad wiring, and the bx is shorted somewhere (I did not turn the breaker off, but used a load based continuity checker).


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## Bob Mariani (Dec 1, 2008)

Silk said:


> Not a code requirement most of the time. It depends on the distance from the scuttle hole and if you have a permanent ladder or stairs to access the attic. If not it is a waste of time and money.


I did not say it was code. But a good practice and was mentioned as a protection of wires that another posted mentioned.


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## gma2rjc (Nov 21, 2008)

They prefer you keep the boxes on top. This makes it impossible for the home owner to cover and hide the JB with boards.


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## diymonkey (Jun 23, 2007)

thanks everyone for the comments/suggestions. I would rather mount the box on top and then run the wires along the joist (wide side). 

I should have pointed this out in my first post, but this is not a picture of my attic. I just grabbed a picture off google so I can doodle on quickly. Regarding the wires in the picture, I thought they were suppose to be run along a 2x4 between the joist (perpendicular). So this is acceptable to have them as shown in the picture?


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## Bob Mariani (Dec 1, 2008)

The ones shown are drilled though the studs and then covered with a nail plate. This is a correct installation.


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## philS (Jul 10, 2007)

J boxes don't just need to be accessible w/o dismantling things. It really helps if they're VISIBLE, which means mounting them up above a level at which some later person might add insulation. Having to crawl on hands and knees feeling your way under a foot of blown in insulation is not fun. If this were my attic I'd add a board from the floor joist up to the rafter and mount the box on that, where it can be seen. Also note that drilling holes in framing members must be done carefully to avoid weakening them. 

With roof trusses it's better to not mess with them at all. Just staple wires along side them when going parallel to them. Where you need to cross them you can always run the wires in the tight angles between the truss members, or you can run along the roof. Code says something precise about this but I just stay at least 1 1/2 inches from the top of the roof sheathing to decrease the chance that some future roofer is going to shove a nail into my wires. (Any mistakes in above, please correct me. I'm here also to learn.)


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## Silk (Feb 8, 2008)

Bob Mariani said:


> The ones shown are drilled though the studs and then covered with a nail plate. This is a correct installation.


*Absolutely not!* Do not start drilling holes thru your trusses!! You are much better off to run a protection strip at least as thick as the wire alongside the wires if you feel you must protect them although you don't even have to do that by code (with a few exceptions).


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## Bob Mariani (Dec 1, 2008)

Silk said:


> *Absolutely not!* Do not start drilling holes thru your trusses!! You are much better off to run a protection strip at least as thick as the wire alongside the wires if you feel you must protect them although you don't even have to do that by code (with a few exceptions).


 I did not think these were trusses. OP said that the wire was already done as is in this picture. So it was inspected. And they look more like 2X6 then 2X4....

Anyway... you would not drill holes in trusses. You can drill holes in ceiling joists that are 2X6 or better.


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## DangerMouse (Jul 17, 2008)

or you can staple them to furring strips mounted to the joists like in this picture. the wires remain accessible above the 15 or so inches of blown cellulose this way. 

DM


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## Scuba_Dave (Jan 16, 2009)

I never drill thru joists unless they are larger
Some 2x6's (like my 2nd floor) are already beyond the span calcs
Drilling a hole in them only weakens them further
I take each instance & verify what the joists are & how far they are spanning
I prefer running a furring strip/2x3/2x4 across the joists & fasten to that

Also take into account if the attic can ever be made living space

In the 1st picture (I know its not yours) I would have run past the ends of ths joists (you can see the cut ends), the down to the bay & down the side of the joist. Slightly more wire but leaves the joists intact if they are slightly "undersized" already

That's one heck of an open un-insulated space DM !!


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## gma2rjc (Nov 21, 2008)

For existing wires running across the tops of the floor trusses, is there a way to mark where they are? I'm putting blown-in insulation in my attic soon. I'd like to be able to find the wires later without having to dig.


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## Bob Mariani (Dec 1, 2008)

That is for the Mouse to get into the attic to sleep.


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## DangerMouse (Jul 17, 2008)

Scuba_Dave said:


> That's one heck of an open un-insulated space DM !!


the roof under it is still insulated... and come next year, it'll all be 15" and more of cellulose....

DM


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## Scuba_Dave (Jan 16, 2009)

gma2rjc said:


> For existing wires running across the tops of the floor trusses, is there a way to mark where they are? I'm putting blown-in insulation in my attic soon. I'd like to be able to find the wires later without having to dig.


Maybe nail a few pieces of furring sticking up along the route & put 'electric" on them?


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## gma2rjc (Nov 21, 2008)

Thanks, that sounds easy.


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## 220/221 (Oct 9, 2007)

I avoid attic jb's as much as I can but when I must do them, I like to keep them up above the insulation. Nothing worse than crawling across trusses/joists, tugging on cables, looking for jb's under insulation.










I know that someone is going to tell me I have too many wires in the JB but I am a trined professional and there is plenty of room in there :thumbup:


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## rgsgww (Jul 5, 2008)

I hate those "stab" bx connectors. Hell for the next guy to remove (which happened to be me).


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## DragonInspector (Apr 8, 2009)

Oh my gosh!!! Talk about making a mountain out of a mole hill.

Simply put. 
If the attic is accessible, then those j-boxes are considered accessible.

The junction boxes you want to install could be mounted either way. However, any wires the run over top of the horizontal beams in the attic need to be physically protected if within 6' of the attic opening or within 2' of the opening if you have pull-down stairs into the attic area. (Code requirement!)
But on a good practice note, because lots of people use the attic as storage space, etc... it would be a better if you tried to keep your Romex cables from laying all over the tops of those horizontal beams in the attic so the don't get stepped on or any storage items placed on them & possible cutting into them @ some point.
Also, if is NOT a good idea to bury these junction boxes in the attic insulation since 1 it makes finding them later harder, but also, the conductors may NOT get the proper ventilation/cooling they may need if buried in insulation in a Hot SummerAttic envirement.
Hope that helps simplifly things for you.
P.S. My gosh 220/221, that's at least 29 fill-points from what I can tell in that picture in what , a standard 1900 box in a Hot Summer Attic?? 
Also, nice stapling huh....(trained proff??)


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## 220/221 (Oct 9, 2007)

It requires _patience_ grasshoppa.:yes:


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## rgsgww (Jul 5, 2008)

Ah there is a spacing requirement near the opening?


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## DragonInspector (Apr 8, 2009)

Yes rgsgww, any non-metallic cables installed in accessible dwelling attics & installed away from the studs edge shall be physically protected & secured to running boards if within the measurements I mentioned earlier.


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## Scuba_Dave (Jan 16, 2009)

Oh my gosh I like mole hills !!
Simply put


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## zpm (Jan 6, 2009)

DragonInspector said:


> if is NOT a good idea to bury these junction boxes in the attic insulation since 1 it makes finding them later harder, but also, the conductors may NOT get the proper ventilation/cooling they may need if buried in insulation in a Hot SummerAttic envirement.


In an attic, stuff buried under insulation will be cooler than stuff in the open air. For example, last October 1st the outside temp at 4PM was about 95. The ambient air temp in my attic at the plate line above the insulation was about 95 or slightly higher. The air temp at the peak exhaust vent was 115. The temp under the insulation at the ceiling sheetrock was less than 80, about the same as the inside temp.


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## rgsgww (Jul 5, 2008)

Its an oven in my attic. I would literally die in there if I went up there when its 100 outside. It lets up to 80 when its only 67 outside.


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