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.
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: ‘‘A,’’ flexible metal conduit ‘‘F,’’ nonmetallic sheathed cable ‘‘N’’ or flexible tubing (loom) ‘‘T.’’
Clamps that are suitable for type MC metal clad cable are marked ‘‘MCI’’ for metal clad interlocking armored cables, ‘‘MCS’’ for metal clad continuous smooth sheath cable, and ‘‘MCC’’ for metal clad continuous corrugated sheath cable. If suitable for all seven types, the clamp is marked ‘‘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
Re: "N" & "T" on steel device boxes#31575 11/25/0309:02 PM11/25/0309:02 PM
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.
Re: "N" & "T" on steel device boxes#31576 11/25/0309:03 PM11/25/0309:03 PM