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#164621 - 06/07/07 09:17 AM Question about metal boxes
EV607797 Offline
Member

Registered: 10/25/06
Posts: 756
Loc: Fredericksburg, VA, USA
Does anybody know what the letters "N" and "T" indicate on Romex clamps with metal boxes? The N is on one side and the T is on the other. I don't think it has anything to do with the manufacturer because I have seen this on several different brands. It's just one of those things that I have always wondered.
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#164636 - 06/07/07 04:28 PM Re: Question about metal boxes [Re: EV607797]
GTE Offline
Member

Registered: 03/26/03
Posts: 48
Loc: Bridgehampton, N.Y. USA
nob & tube

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#164639 - 06/07/07 05:31 PM Re: Question about metal boxes [Re: GTE]
e57 Offline
Member

Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
I'm not one who could bag on spelling... Isn't it Knob & Tube? Nob is a town in Isreal.

Otherwise, I have no idea.
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#164662 - 06/08/07 08:35 AM Re: Question about metal boxes [Re: e57]
Alan Nadon Offline
Member

Registered: 03/10/05
Posts: 398
Loc: Elkhart, IN. USA
The mark is to show what the clamp is listed for. I'm sure the N is for NM cable. Don't know about the T.
Stop at the supply house and look at their box catalogue it will have all the clamps listed. That is where I had to go last time to check on AC cable clamps.
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#165288 - 06/25/07 04:27 AM Re: Question about metal boxes [Re: Alan Nadon]
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
From the UL White Book:

"The clamps are marked with the following letters or combinations thereof to indicate that they are suitable for use with armored cable (β€˜β€˜A’’): flexible metal conduit – β€˜β€˜F,’’ nonmetallic-sheathed cable – β€˜β€˜N,’’ or flexible tubing (loom) – β€˜β€˜T.’’ Clamps
suitable for Type MC metal-clad cable are marked β€˜β€˜MCI’’ for metal-clad
interlocking armored cable, β€˜β€˜MCI-A’’ for metal-clad interlocking armor
ground cable, β€˜β€˜MCS’’ for metal-clad continuous smooth-sheath cable, and
β€˜β€˜MCC’’ for metal-clad continuous corrugated-sheath cable. If suitable for all
seven types, the clamp is marked β€˜β€˜ALL.’’ Clamps suitable for nonmetallicsheathed
cable are also suitable for multiconductor underground feeder and
branch circuit cable where used in dry locations."

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#165306 - 06/25/07 09:03 AM Re: Question about metal boxes [Re: electure]
Alan Nadon Offline
Member

Registered: 03/10/05
Posts: 398
Loc: Elkhart, IN. USA
Thank You.
Alan--
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