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.
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.
"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 suitable for Type MC metal-clad cable are marked ‘‘MCI’’ for metal-clad interlocking armored cable, ‘‘MCI-A’’ for metal-clad interlocking armor ground cable, ‘‘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 nonmetallicsheathed cable are also suitable for multiconductor underground feeder and branch circuit cable where used in dry locations."
