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#31573 - 11/25/03 05:10 PM "N" & "T" on steel device boxes
Mr. Ed Offline
Member

Registered: 08/15/03
Posts: 30
Loc: Silver Creek, NY USA
This may be a dumb question but... I've been doi'n this work for forty plus years and I've always wondered why the clamp (usually on a 1 gang device box) is marked with a "N" over one opening and "T" over the other.

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#31574 - 11/25/03 05:59 PM Re: "N" & "T" on steel device boxes
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
 Quote:
CLAMPS

Boxes may or may not be provided with clamps.

When clamps are provided, the carton is marked to indicate the type of wiring system or combination of systems for which they have been tested.

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
that are suitable for type MC metal clad cable are marked β€˜β€˜MCI’’ for metal clad interlocking armored cables, 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 nonmetallic sheathed cable are also suitable for multiconductor
underground feeder and branch circuit cable where used in dry locations.

Clamps have been tested for securing only one cable per clamp, except multiple section clamps are considered suitable for securing one cable under each section of the clamp, each cable entering a separate knockout.
_________________________
Joe Tedesco, NEC Consultant

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#31575 - 11/25/03 06:02 PM Re: "N" & "T" on steel device boxes
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
Hey Mr.Ed
That is something I was wondering as well!
My pancake box in the photos section has an "N" on the romex clamp.
I had absolutely no clue, other than the "N" might stand for neutral (noodle) from the old K&T days, or that it denotes the clamp is meant for NM cable.(without any basis, just guesses.)
Now, I remember seeing "T" on other clamps, like you say, so now I'm completely lost in space.

Please...somebody explain...S

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#31576 - 11/25/03 06:03 PM Re: "N" & "T" on steel device boxes
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
Joe!!
Thanks, while I was stumbling over my keyboard, you were answering!

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#31577 - 11/25/03 06:05 PM Re: "N" & "T" on steel device boxes
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Wow, you guys are all over this thing!

I was just searching for some old posts about that...

I found one of them http://electrical-contractor.net/ubb/Forum1/HTML/000183.html

P. S. Wasn't there discussion in one of the posts about the need to separate the conductors, specifically in K&T wiring?

[This message has been edited by ThinkGood (edited 11-25-2003).]

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#31578 - 11/25/03 07:07 PM Re: "N" & "T" on steel device boxes
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
Whenever a question comes up that is related to a product look here:
http://joetedesco.com/2003geninfo.pdf

Save this 2003 UL White Book to Your Desktop, worth its weight in Copper!
_________________________
Joe Tedesco, NEC Consultant

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#31579 - 11/26/03 04:18 PM Re: "N" & "T" on steel device boxes
Mr. Ed Offline
Member

Registered: 08/15/03
Posts: 30
Loc: Silver Creek, NY USA
Thanks for all the replies. Love to read all the threads. Am usually on till 2AM going thru all sites!

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