PDA

View Full Version : Working length of wire



beekerc
11-22-2008, 08:46 PM
From several sources I have come to understand that there needs to be 6 inches of wire extending from the front edge of an outlet box, light fixture box or junction box for the box to be properly prepared for the rough-in inspection. including the depth of the box, that makes 8 to 9 inches of wire, per cable that enters the box, that has to be folded and stuffed into the box. the more cables entering the box the more this becomes an issue.

my question is this. once the rough-in inspection has been done, is there anything that says that I can't shorten the working length to around 3 to 4 inches (extending from the front)? that still leaves enough length to work outside the box but allows for less material that needs to be stuffed into the box.

is the 6 inches an actual NEC code requirement/regulation, or simply a "best practices" figure?

Thanks
B

Igor
11-22-2008, 09:20 PM
The NEC (300.14) requires at least 6" of free conductor, measured from the point where the conductor emerges from the cable sheath or raceway, and also the conductors must extend at least 3" from the opening in the box, if any dimension of the opening is less than 8". Note that the 6" is not measured from the front of the box.

beekerc
11-23-2008, 12:33 AM
just about every DIY book i read says between 6" and 8" from the front of the box, which doesn't take into account box depth, but even so, that's still a lot of wire.

That NEC code, while written in regulatory mumbo-jumbo, does clarify the question rather nicely, although i did have to read it about 4 times, just to make sure i got it.

Thanks
B

jwelectric
11-23-2008, 04:43 AM
just about every DIY book i read says between 6" and 8" from the front of the box, which doesn't take into account box depth, but even so, that's still a lot of wire.

That NEC code, while written in regulatory mumbo-jumbo, does clarify the question rather nicely, although i did have to read it about 4 times, just to make sure i got it.

Thanks
B

Here is what the only book that counts says

300.14 Length of Free Conductors at Outlets, Junctions, and Switch Points.
At least 150 mm (6 in.) of free conductor, measured from the point in the box where it emerges from its raceway or cable sheath, shall be left at each outlet, junction, and switch point for splices or the connection of luminaires or devices. Where the opening to an outlet, junction, or switch point is less than 200 mm (8 in.) in any dimension, each conductor shall be long enough to extend at least 75 mm (3 in.) outside the opening.
Exception: Conductors that are not spliced or terminated at the outlet, junction, or switch point shall not be required to comply with 300.14.

hj
11-23-2008, 07:02 AM
If you do not have 3" of wire extending from the box, you are going to have to be very dextrous to make the connection to the device.

jar546
11-23-2008, 10:02 AM
You cannot shorten the compliant wires to less than required after the inspection. At this point you are now non-compliant and a spot check of the devices during the final inspection is no time to fail an inspection, especially when you will be forced into fishing new wire.

I see no reason to shorten to less than required and you will just make it harder for yourself when working with those wires.

maintenanceguy
11-23-2008, 10:57 AM
Leave the wire long. It makes hooking up devices so much easier later. If you have so many wires in a box that there isn't room to tuck the wires into the box, I have a feeling you may need to use bigger boxes.

Thatguy
11-23-2008, 12:30 PM
Leave them long unless you like soldering wires in a cramped box.

Billy_Bob
11-23-2008, 03:27 PM
There are a few tricks to this...

Use larger boxes which need plaster rings in the front.

With a switch, you need to stick the wires and the switch into the box. With a light fixture, nothing needs to go into the box except the wires (more room!). So run power to the light fixture instead of to the switch. Just run one wire to the switch.

If you have a bunch of wires which need to connect to each other, use a junction box in an accessible place like attic or basement.

Use a box extender then you get twice the depth.

Or use a double gang box with a single gang plaster ring.

Here are some pictures...
http://electrical.hardwarestore.com/14-45-box-extensions.aspx

beekerc
11-23-2008, 11:55 PM
You cannot shorten the compliant wires to less than required after the inspection. At this point you are now non-compliant and a spot check of the devices during the final inspection is no time to fail an inspection, especially when you will be forced into fishing new wire.

I see no reason to shorten to less than required and you will just make it harder for yourself when working with those wires.

I would never shorten wire less than code. the main point of in my inquiry was the basis for the "6~8 inches beyond the front of the box", whether that was set in stone (NEC code) or just "good advice". now seeing what the actual code says, (6 inches from box entry, with at least 3 inches past the box face) this lets me know that i can shorten what i did for the rough in (6 inches from the box front) and how long/short i can make it and still be compliant.

i really can appreciate having enough wire length for retro work. i had to upgrade some bathroom outlets to GFCI and replace some switches a few years ago. every single device that i replaced, i had to pigtail the wires because the original work (1968) left less than 1 inch of workable wire from the box front.


Leave them long unless you like soldering wires in a cramped box.

I would never solder wires in a box. I'm sure there's lots of code reasons with lots of basis in cold hard physics. but to me, soldering junctions/splices/devices just seems like a bad idea to me.



Use larger boxes which need plaster rings in the front.

Lots of good tips billy_bob.
I actually did just that not 2 hours ago. I needed to get an extra wire run into a 18 CU box that already had a GFCI in it. the reason i didn't use a bigger box is because the spacing between the framing studs did not allow me the side nailer box and the only thing i found was the box with the front flange for attaching to metal studs and they only come in 18CU. after further wracking my brain, i nervously whipped out my saw-z-all and cut a chunk out of the stud and mounted a 2-gang, deep, j-box and put a 1-gang mud ring. don't worry, the wall is not load bearing. it was put up in front of a concrete foundation wall for the sheetrock to be nailed to, and give me framing space to run wires and insulate.


With a switch, you need to stick the wires and the switch into the box. With a light fixture, nothing needs to go into the box except the wires (more room!). So run power to the light fixture instead of to the switch. Just run one wire to the switch.

call me archaic, but if i can help it, i prefer to always go power -> switch -> device. I know how to wire up the switch-at-the-end configuration, but personally, i prefer not to use it.


If you have a bunch of wires which need to connect to each other, use a junction box in an accessible place like attic or basement.

have done that too. I even put a telescoping ladder to make getting into the attic easier, as well as stringing some lights and a couple outlets up there too. in the basement, i decided on a drop ceiling for two reasons - (A) so i can easily access the upper space if i need to run new network or video wires and (B) so that j-boxes as hidden, but accessible.


Use a box extender then you get twice the depth.

did not know that such things existed. i'll have to go scope one out next time i'm at the big orange box store.

jar546
11-24-2008, 03:59 AM
The last 5 statements you quoted were not by me. Only the first one. Just an FYI

Billy_Bob
11-24-2008, 04:30 AM
...did not know that such things existed. i'll have to go scope one out next time i'm at the big orange box store.

They might not have some of that stuff. If not, try an electrical supply.

jwelectric
11-24-2008, 05:50 AM
The last 5 statements you quoted were not by me. Only the first one. Just an FYI

Maybe you were thinking them and he quoted your thouhgts :D

Then again maybe you read them and he was quoting what you were reading. :D

But maybe he just hasn't figured things out as yet after all he is not sure about 6 inches :D :D

beekerc
11-24-2008, 11:39 AM
The last 5 statements you quoted were not by me. Only the first one. Just an FYI

A simple case of not realizing that the QUOTE meta-tags included the original poster's name, and since i can't get multiple user quotes at the touch of one button, i simply cut an paste the first QUOTE tag, which happened do be yours.


Maybe you were thinking them and he quoted your thoughts

Then again maybe you read them and he was quoting what you were reading.

But maybe he just hasn't figured things out as yet after all he is not sure about 6 inches

see, i figured it out now. and i'll know better for next time. :o
nah, just don't spend enough time on the nuaces of forum posting and using all the tricks and features when drafting messages.

after trimming out a few more outlets, i've found that about 7 inches total (from box entry) works best for me. that gives about 4 to 4-1/2 inches from the box front where before i was going a full 6 inches from the front. you'd think that 1-1/2 inches isn't much, but that ammounts to one fold, across 3 wire per cable. in a 1-gang box, that can save a lot of space and it still leaves a good bit of working length.