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device wiring/box fill

This topic contains 23 replies, has 12 voices, and was last updated by  theamcguy 9 months, 1 week ago.

Viewing 20 posts - 1 through 20 (of 24 total)
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  • #566518

    TopNotch
    Pro
    elmwood park, NJ

    I have never learned the correct way to figure box fill. I have a mental road block on certain things and Im not sure how the code reads.

    I have seen all kinds of weird electrical wiring things too.

    Is it required to pigtail to each device in each box to maintain the circuit if the device fails? Or just the neutral for safety? I see outlets used to bridge the circuit all of the time.

    What about a multi gang switch? I have seen a single feed go to one device then jumpers back stabbed from one switch to the other for as many as there are. This frees up a lot of space in a box verses pig tailing each one but is it legal? Again if one device goes or the jumper get nicked the whole thing is dead. My gut says its not allowed.

    On the other hand, it is very very very rare devices just go bad.

    Working Pro since 1993

    Tom M

    #566546

    jponto07
    Moderator
    Bloomington, IN

    I always pigtail when I wire outlets…unless it’s the last device on the circuit. It does add more to the box, but it is also a precaution against loosing everything down the line.

    Is it legal to do it the other way you suggested though? I don’t have that answer. Learning to efficiently fold wires in a box goes a long way too.

    Jon P.
    Timber Carpentry & Construction
    https://www.facebook.com/timbercarpentry/
    Instagram

    #566561

    theamcguy
    Pro
    Fayetteville, NC

    Learning to efficiently fold wires in a box goes a long way too.

    That helps as well. If you find you have too many wires in a box use a connector box for the pigtail and run just a single wire to the outlet or switch box.

    Automotive Pro
    Fayetteville, NC

    #566585

    kurt@welkerhomes.com
    Pro
    Owatonna, MN - Minnesota

    here are some cahrts and diagrams on how many wires you can have in a box. Pigtails are required and do simplify things. If you are ganging outlets together, I believe it is permissable to have 1 set of pigtails then loop form device to device

    #566640

    Seven-Delta-FortyOne
    Pro
    The Emerald Triangle, Northern California

    Pigtails are required for the neutral in an MWBC. If the device should be removed or fail, or the neutral disconnected, you would then have 240 volts on that circuit instead of 120.

    Box fill calculations are not all that difficult, IF, you have the right info. You need the NEC, and you need to find the cross-section area of all the wires in the box, counting all grounds as 1. Then you need to find the cubic inch size of the box.

    If I have a string of devices, I’ll just in and out on the device. But, I never use the backstab. Those things fail at an alarming rate, allowing the connection to become loose, heating up the device, and burning it up. I only use the screw terminal.

    I’ll try to copy and paste the code page for box-fill calcs for you. I’m not super good with computers, but I have a PDF copy of the code on my laptop, and I’ll work on it.

    Delta

    Goin' Down In Flames........

    #566659

    Yes you need too for sure on ground wire theres no way around it. Jumping wires from switch to switch is hack style of doing things. Don’t do that. I also always electric tape everything from nuts to around the outlet so theres so metal exposed with live wires just hanging there waiting for that ground to make contact somehow then pop or you don’t hear that and house burns down. Lots of building codes are minimum requirements you can always make it better. You can even heat sink your wire nuts if you choice to

    #566674

    jponto07
    Moderator
    Bloomington, IN

    I also always electric tape everything from nuts to around the outlet so theres so metal exposed with live wires just hanging there waiting for that ground to make contact somehow then pop or you don’t hear that and house burns down.

    I always tape around the device as well. Especially when I’m working with metal boxes! As for the wire nuts, I see no point in taping them. Twist the wires properly with linesman pliers and trim to the proper length prior to nutting and you’ll never have an issue.

    Jon P.
    Timber Carpentry & Construction
    https://www.facebook.com/timbercarpentry/
    Instagram

    #566684

    If a pigtail is 12 inches or longer it gets counted as an additional wire. Each device counts 2 of the largest wire size. The grounds count as one of the largest ground wire.

    Example: 10-2 with ground coming in, adding a receptacle and feeding down line with 12-2 with ground. 10 AWG wire calls for 2.5 cubic inch. 12 AWG wire calls for 2.25 cubic inch.

    10 AWG black/white together = 5
    12 AWG black/white together = 4.5
    10 AWG ground plus 12 AWG ground = 2.5
    Device = 2 x 2.5 or 5.
    Total is 17 cubic inches.

    If using clamps inside the box, they take up free air space and have to be allowed for as well.

    Anything is possible if your wallet is thick enough ~ my father

    #566713

    TopNotch
    Pro
    elmwood park, NJ

    We need to take this in baby steps :laughing: I understand there are a variety of circumstances like type of box and clamp that changes things.

    In Kurts #3 picture I dont understand why I see one strap/yoke counted as one when their are two sides and one clamp counted when I see two?

    That first photo of the loop method I have seen. And I couldn’t agree more about pre folding wires nicely so its cleaner to stuff back in. ( 14 is so much nicer than 12 AWG for that) Same with taping the side lugs of a device that could bump on metal boxes.

    The whole folding wire thing has a ryhme and reason too as to what you going to wire first and bury and whats last. I also dont like to cross my grounds near the hot side.

    Working Pro since 1993

    Tom M

    #569141

    Seven-Delta-FortyOne
    Pro
    The Emerald Triangle, Northern California

    Sorry, got busy and forgot about this thread.

    Anyway, to much to copy and paste, but it’s NEC article 314.16, and Tables 314.16(A) and 314.16(B). Pretty easy reading.

    As far as taping receptacles, it’s actually not something the pros really do all that much, except for maybe metal boxes, or if you use those stupid metal clips for remodel boxes. Hate those things.

    If you wire neatly and push the grounds in the back, you shouldn’t have any issue with grounded circuits.

    Delta

    Goin' Down In Flames........

    #569154

    Sorry, got busy and forgot about this thread.

    Anyway, to much to copy and paste, but it’s NEC article 314.16, and Tables 314.16(A) and 314.16(B). Pretty easy reading.

    As far as taping receptacles, it’s actually not something the pros really do all that much, except for maybe metal boxes, or if you use those stupid metal clips for remodel boxes. Hate those things.

    If you wire neatly and push the grounds in the back, you shouldn’t have any issue with grounded circuits.

    Delta

    I can’t tell you how many Outlet breakers I have blowen doing drywall work pulling plunges out in metal box rings hitting screw heads .

    Always willing to learn .

    #595926

    roninohio
    Pro
    New Franklin, OH

    Anyone know where to buy a triple light switch that fits in a single box?
    I have never seen any like in this house before.
    They look like regular light switches but turned horizontal and stacked on top of each other.
    Like this but not rockers http://www.acehardware.com/product/index.jsp?productId=29265746&KPID=17510625&cid=CAPLA:G:Shopping_-_Electrical_-_New&pla=pla_17510625&k_clickid=12b4c5d0-e17f-4c6d-9f28-72f22f9af900

    #595933

    Doobie
    Pro
    Ajax, ON

    Anyone know where to buy a triple light switch that fits in a single box?
    I have never seen any like in this house before.
    They look like regular light switches but turned horizontal and stacked on top of each other.
    Like this but not rockers http://www.acehardware.com/product/index.jsp?productId=29265746&KPID=17510625&cid=CAPLA:G:Shopping_-_Electrical_-_New&pla=pla_17510625&k_clickid=12b4c5d0-e17f-4c6d-9f28-72f22f9af900

    I have that, but I bought it and installed it about 12 years ago. Pretty sure I got it at HD.

    EDIT: Look what I found. Looks like HD still sells it.

    http://www.homedepot.com/p/Leviton-Decora-15-Amp-3-Rocker-Combination-Switch-White-R62-01755-0WS/100356847

    @roninohio

    Kevin.

    #595970

    roninohio
    Pro
    New Franklin, OH

    You are on the right track with me but they look like this but 3 switches.
    http://www.homedepot.com/p/Leviton-15-Amp-Combination-Double-Switch-Light-Almond-R56-05224-2TS/202035015

    #595995

    Sprokitz
    Pro
    Easton, Pa

    You are on the right track with me but they look like this but 3 switches.
    http://www.homedepot.com/p/Leviton-15-Amp-Combination-Double-Switch-Light-Almond-R56-05224-2TS/202035015

    Are they separate toggles that fit in a mounting strap ? They would be called Despard Interchangeables I’ll look for a link

    #595996

    Sprokitz
    Pro
    Easton, Pa
    #596027

    theamcguy
    Pro
    Fayetteville, NC

    I remember those kinds of switches but haven’t seen them in years. Figures they would only be available at a historic hardware place.

    Automotive Pro
    Fayetteville, NC

    #596038

    roninohio
    Pro
    New Franklin, OH

    @roninohio Here ya go….

    http://www.historichomehardware.com/store/electrical-despard-interchangeable-c-27_31.html

    https://www.amazon.com/Legrand-Pass-Seymour-ACD1ICC8-Despard-277-Volt/dp/B000BQ7VVE

    I believe you found it! Not exact but will work. The demo guy threw all the original switch covers away. I will take a picture of what is there now.

    #596066

    TopNotch
    Pro
    elmwood park, NJ

    I would think that device would need a square box with a raised cover for extra space.

    Working Pro since 1993

    Tom M

    #596073

    TopNotch
    Pro
    elmwood park, NJ

    here are some cahrts and diagrams on how many wires you can have in a box. Pigtails are required and do simplify things. If you are ganging outlets together, I believe it is permissable to have 1 set of pigtails then loop form device to device

    Ok so as I look at this again and absorb more a few things strike me.

    When I look at picture 3 I see straps yokes are considered conductors….ok its not in the box its outside but now I know.

    The wires coming in are obviously easy to count as conductors. My only odd thought was why 2 grounds count as one? And why do those clamps calculations count only on one end of the box? Clearly their are two sides of the box all consuming interior space.

    Lastly Im going to invent a tool that spirals pigtails into springs to make pulling devices in and out easier 🙂

    Working Pro since 1993

    Tom M

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