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Poll

Should you pre-twist the wire for wire-nuts?

Yes
- 4 (23.5%)
No
- 6 (35.3%)
Doesn't Matter
- 4 (23.5%)
Wire Nuts Are Evil
- 3 (17.6%)

Total Members Voted: 17


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Author Topic: No Box, Safe?  (Read 39967 times)

Jeff Bankston

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Re: No Box, Safe?
« Reply #80 on: September 16, 2014, 03:48:03 PM »

I will have a go.

What about these boxes which mount into the plasterboard? (or drywall as I think you call it).




Steve.
i will never use a plastic. they are junk. i have seen and ben told by others that the plactic boxes in their houses are broken. plastic isnt allowed in commercial(yet). metal boxes are the only way to go.
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Steve M Smith

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Re: No Box, Safe?
« Reply #81 on: September 16, 2014, 05:02:50 PM »

I wouldn't use them by choice either, although I have used them a couple of times where using a metal box was not possible.

What if they were a different colour?!


Steve.
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Jeff Bankston

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Re: No Box, Safe?
« Reply #82 on: September 16, 2014, 05:24:00 PM »

I wouldn't use them by choice either, although I have used them a couple of times where using a metal box was not possible.

What if they were a different colour?!


Steve.
green.....no blue
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Steve M Smith

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Re: No Box, Safe?
« Reply #83 on: September 16, 2014, 06:10:28 PM »

I have seen them with red, yellow and blue threaded insert clamp pieces but no green... sorry!


Steve.
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Jeff Bankston

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Re: No Box, Safe?
« Reply #84 on: September 16, 2014, 06:12:54 PM »

I have seen them with red, yellow and blue threaded insert clamp pieces but no green... sorry!


Steve.
the sadness creeps back :(
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Stephen Swaffer

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Re: No Box, Safe?
« Reply #85 on: September 16, 2014, 10:19:06 PM »

Going strictly by the NEC, non-metallic boxes are acceptable anywhere you are allowed to use nonmetallic sheathed cable, or knob and tube wiring or open wiring on insulators(NEC 2011 314.3).  NM (romex) is allowed -by the NEC-in certain types of construction (wood frame essentially) no matter the use.  I realize that most local AHJ will not allow NM in commercial-but that is actually going above and beyond the NEC.

Which are better?  PVC may get hard and crack or strip threads.  Metal often rusts-and threads get stripped.  Pick your poison-they all can be a problem.

Jonathan is right as far as fire with metal stud and plaster-but metal boxes require bonding.  I would think the code addresses bonding metal studs-but not sure if it happens?  I haven't actually done any new wiring with metal studs, though.  Without a box you leave open the possibility of conductors touching something metalic they should not they may not be adequately bonded, don't you?

As for color-stop by the paint department at your favorite store-they sell spray paint for plastic and for metal in a large variety of colors.  Then let the AHJ stuggle to find chapter and verse why you can't paint the boxes your favorite color so you get a warm fuzzy feeling installing them.
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Steve Swaffer

Jeff Bankston

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Re: No Box, Safe?
« Reply #86 on: September 17, 2014, 02:25:37 AM »

Going strictly by the NEC, non-metallic boxes are acceptable anywhere you are allowed to use nonmetallic sheathed cable, or knob and tube wiring or open wiring on insulators(NEC 2011 314.3).  NM (romex) is allowed -by the NEC-in certain types of construction (wood frame essentially) no matter the use.  I realize that most local AHJ will not allow NM in commercial-but that is actually going above and beyond the NEC.

Which are better?  PVC may get hard and crack or strip threads.  Metal often rusts-and threads get stripped.  Pick your poison-they all can be a problem.

Jonathan is right as far as fire with metal stud and plaster-but metal boxes require bonding.  I would think the code addresses bonding metal studs-but not sure if it happens?  I haven't actually done any new wiring with metal studs, though.  Without a box you leave open the possibility of conductors touching something metalic they should not they may not be adequately bonded, don't you?

As for color-stop by the paint department at your favorite store-they sell spray paint for plastic and for metal in a large variety of colors.  Then let the AHJ stuggle to find chapter and verse why you can't paint the boxes your favorite color so you get a warm fuzzy feeling installing them.
metal boxes are screwed to metal studs or other metal mounting devices that are screwed to metal studs that the metal boxes are screwed to. a ground pigtal wire is screwed to the box whick is screwed to the stud and the studs are all screwed together and we are all screwed and bonded.
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Mike Sokol

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Re: No Box, Safe?
« Reply #87 on: September 17, 2014, 07:14:17 AM »

metal boxes are screwed to metal studs or other metal mounting devices that are screwed to metal studs that the metal boxes are screwed to. a ground pigtal wire is screwed to the box whick is screwed to the stud and the studs are all screwed together and we are all screwed and bonded.

That doesn't work for a "technical" ground since connecting your audio grounds to building steel is the "best" way to create a bunch of ground loop hum. In that case, the best way is to run a second technical ground wire (green/yellow-stripe) to isolated ground receptacles. I've talked to a few inspectors in Maryland, and they do insist that metal boxes are used in commercial installation, but don't insist that they're bonded to building steel since they're bonded to the BX cable. It seems there's a lot of local code differences as to proper bonding/grounding of receptacles. If you CAN use non-metalic boxes and Romex according to your local code, that would reduce a lot of ground-loop hum.
 

Jeff Bankston

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Re: No Box, Safe?
« Reply #88 on: September 17, 2014, 08:30:12 AM »

That doesn't work for a "technical" ground since connecting your audio grounds to building steel is the "best" way to create a bunch of ground loop hum. In that case, the best way is to run a second technical ground wire (green/yellow-stripe) to isolated ground receptacles. I've talked to a few inspectors in Maryland, and they do insist that metal boxes are used in commercial installation, but don't insist that they're bonded to building steel since they're bonded to the BX cable. It seems there's a lot of local code differences as to proper bonding/grounding of receptacles. If you CAN use non-metalic boxes and Romex according to your local code, that would reduce a lot of ground-loop hum.
the way i posted is the way we have to do ot in la. tis ben done that way since i move here in 1987. and there no way to get around it either. a metal box screwed to a metal stud. and every conduit has to have a ground wire and ever box has to have a ground pig tail and every concentric knock out out has to have a ground bushing with a seperate ground wire. they have had lots of conduits pulled apart in earthquakes and they want everyhting grounded. the emt/gal/metal flex is strapped or tie wired to the metal studs. mc/ac cable is done the same way. the only way to not have the the electrical boxes and conduit fastened to the metal studs is use all plastic and thats not allowed. in la they still consider the conduit a mechanical ground and the ground wire the electrical ground. they dont care about audio hum all the care about is everything staying bonded and grounded in an earthquake. these earthquakes can shake stuff apart. i never buy concentric ko boxes. i buy 4s and 5s boxex with the ko's i need and punch my own holes in larger boxes.
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Frank DeWitt

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Re: No Box, Safe?
« Reply #89 on: September 17, 2014, 10:04:17 AM »

and there no way to get around it either.
snip
they dont care about audio hum all the care about is everything staying bonded and grounded in an earthquake.

One way around it most places is to use isolated ground receptacles.  The strap that connects the receptacles to the box is NOT connected to the safety ground terminals in the receptacle.  They are connected with a separate ground wire back to the panel,  not to the box.

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Re: No Box, Safe?
« Reply #89 on: September 17, 2014, 10:04:17 AM »


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