Wooden stud bushings

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JFletcher

Senior Member
Location
Williamsburg, VA
Smart $ said:
While EMT "bushings" may appease some inspector(s), the pieces are technically not EMT unless installed as a complete run. As suggested, those 2.5 inch long pieces of EMT are just steel bushings... so they do not qualify under Exception No. 1, not are they the required 1/16" thick. You'd have to use bushings made of rigid steel conduit to meet the 1/16" thickness requirement.
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How does the length of the conduit affect its listing? If I had a 4" piece of EMT coming from breaker panel, thru a stud, and into a 1900 box, it would be okay, but a 4" piece of EMT to protect NM thru a stud isnt kosher?

Also, EMT that is 1.25" or larger has a wall thickness of 1.65mm. IMC of any trade size is >1.6mm; no need for RMC.
 
Smart $

Smart $

Esteemed Member
Location
Ohio
JFletcher said:
How does the length of the conduit affect its listing? If I had a 4" piece of EMT coming from breaker panel, thru a stud, and into a 1900 box, it would be okay, but a 4" piece of EMT to protect NM thru a stud isnt kosher?
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It's not the length. It's whether or not it installed as a complete run. That's the way the Code reads. Don't shoot the messenger.

Also, EMT that is 1.25" or larger has a wall thickness of 1.65mm. IMC of any trade size is >1.6mm; no need for RMC.
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You are correct. I said what I said because IMC isn't as commonly available in a lot of locations, and if you want to bore a 1.510" diameter hole for a single NM cable, go for it.
 
J

JFletcher

Senior Member
Location
Williamsburg, VA
Smart $ said:
It's not the length. It's whether or not it installed as a complete run. That's the way the Code reads. Don't shoot the messenger.


You are correct. I said what I said because IMC isn't as commonly available in a lot of locations, and if you want to bore a 1.510" diameter hole for a single NM cable, go for it.
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I've only ever bought IMC once; a 1" stick to use as a rod for my spools of cable. Didnt know it wasnt readily available everywhere. and no ty on the huge hole; 7/8" is plenty big enough for most residential, save the SE cable, tho I did see the A/V guys putting in 1 1/4" ENT today. HDMI cable...
 
Smart $

Smart $

Esteemed Member
Location
Ohio
iwire said:
Can you point us to a section that says the item with a UL tag that says EMT is not EMT?
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If I have a UL listed panelboard and use it as a doorstop, is it a panelboard because it is UL listed as such or is it just a doorstop.

Same goes for EMT.

Then you have 358.30 general statement which leads ultimately to 300.18(A).
 
J

JFletcher

Senior Member
Location
Williamsburg, VA
Smart $ said:
If I have a UL listed panelboard and use it as a doorstop, is it a panelboard because it is UL listed as such or is it just a doorstop.

Same goes for EMT.

Then you have 358.30 general statement which leads ultimately to 300.18(A).
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300.18 exception:

"Short sections of raceways used to contain conductors or cable assemblies for protection from physical damage shall not be required to be installed complete between outlet, junction, or splicing points"

Securely fastening a short section of pipe may be a challenge; I dont suppose a near press-fit of the pipe thru the horizontal hole would be acceptable. or do such bushings or nipples have to be supported at all?

This is all academia anyway; I do not know of anyone who would go thru the trouble of a metal bushing in wood when a 16 cent nail plate that takes 10 seconds to install would do.
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Everything I've seen here in CA is 2x6 studs now (because of insulation requirements), so nobody even needs nail plates any more, unless it's remodel work.

That said, when I added a room on my house a few years ago, I ran out of sheetrock screws in mid hang, so I grabbed some long ones I had laying around rather than stop and make another trip to Home Despot. Damned if I didn't hit a freaking wire... :slaphead:
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Smart $ said:
If I have a UL listed panelboard and use it as a doorstop, is it a panelboard because it is UL listed as such or is it just a doorstop.

Same goes for EMT.

Then you have 358.30 general statement which leads ultimately to 300.18(A).
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It is still a panelboard you happen to be using for something else.

But stick with EMT it is EMT regardless of its use. If it is a compleate raceway system is another matter.
 
kwired

kwired

Electron manager
Location
NE Nebraska
Maybe OP has really hard wood and it has sharp edges? Need a reaming/chamfering type of bit of some type to round those edges before pulling cables.:cool:
 
Smart $

Smart $

Esteemed Member
Location
Ohio
iwire said:
It is still a panelboard you happen to be using for something else.

But stick with EMT it is EMT regardless of its use. If it is a compleate raceway system is another matter.
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You're right. It is still a panelboard... but it is being used only as a doorstop and not subject to NEC purview as such. In effect, not a panelboard.

When Code refers to EMT (in other than Article 358, Part III), it's a referring to the wiring method and the conduit raceway, but not when used as sleeve or bushing, which means, in effect, it is not EMT under Code purview.

JFletcher said:
300.18 exception:

"Short sections of raceways used to contain conductors or cable assemblies for protection from physical damage shall not be required to be installed complete between outlet, junction, or splicing points"

Securely fastening a short section of pipe may be a challenge; I dont suppose a near press-fit of the pipe thru the horizontal hole would be acceptable. or do such bushings or nipples have to be supported at all?
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See above.

This is all academia anyway; I do not know of anyone who would go thru the trouble of a metal bushing in wood when a 16 cent nail plate that takes 10 seconds to install would do.
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Exactly... but in a pinch, it provides a Code-compliant option.
 
iwire

iwire

Moderator
Staff member
Location
Massachusetts
Smart $ said:
While EMT "bushings" may appease some inspector(s), the pieces are technically not EMT unless installed as a complete run.
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Smart, look at what I made bold above.

There is nothing in the NEC to back that up.

I don't why you said it but in my opinion it is false.
 
B

badbanano

Member
Location
US
A steel nipple would have to be grounded equally to the conductor ampacity on both ends. It's nonsense, whatever he thinks.

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