ECN Forum Forums General Topics of the Trade General Discussion Area 3/8"? NM Connectors

Why do they call them 3/8" Connectors instead of 1/2"? They use 1/2" trade size threads, are for 1/2" wide cable, hmmm...That one has bugged me since my first day as an apprentice many moons ago...



(This was in another thread, but I thought it was worthy of it's own...)

good one!
i wonder if there is some relation to thread size?

But the thread size is 1/2" trade (fits into a 7/8" diameter KO just like 1/2" GRC does...)

Nothing on it measures 3/8 of an inch!

It uses 1/2" Locknuts... the same ones that fit on a 1/2" GRC...

GE has one size smaller KO in their residential panels than a 1/2" trade size will fit... This would seem to me to be 3/8" trade size, but it's too small for 3/8" connectors!

What gives?

dunno,
the 3/4" is just that
the 1" is also
every other connector follows suit...

hmmm, gotta find the box & read it..!

I just came to a realization! The reason I haven't read listing or labelling on a lot of materials is that I buy only what I need for the job, I'm so small-time that I rarely buy boxes or cases of anything... I don't have a 3/8" connector box, just a bunch of loose ones!

That explains a lot!

Anyway, yep, the other connectors agree with trade sizes...

[This message has been edited by sparky66wv (edited 05-09-2001).]

The reason that they are called 3/8 is because back in the days before romex, when there was only BX and greenfield the BX came in 3/8", 1/2" 3/4 and so on, each requiring a seperate connector. However the 1/2 ko was suitable for both the smaller sizes, so it's threads and locknuts were used. Then the connectors evolved so that one connector could handle both 3/8 and 1/2 sizes. It's not so noticeable with bx anymore, but with greenfield there is an obvious difference between the sizes.

Thanks! Now I know!

thanks silverbk !

i was starting to think it was some sort of conspiracy....