Hello, 

Does anyone know a manufacturer, distributor, or online store where I
can buy 100 or less 3/8" trade size non-metallic clamps (cable
connectors) that use a 3/8" knockout.  The hole size should be 5/8" in
the electrical box.

I do not need a 3/8" clamp that uses a 1/2" knockout.  These are very
common but use a much larger knockout hole of 7/8".  This is too big
for me.

The only place I have found these are in an under cabinet GE
flourecent lamp fixture that I purchased at home depot.  They come in
the product as an optional piece of hardware if you need the romex to
exit out of the thin back of the lamp.  This lamp is too thin to use
the normal 1/2" trade size knock out.  This fitting is perfect for my
5/8" holes.

I think that this fitting has a symbol of a RU merged on it.  I could
not figure out if this is a manufacturer or a safety registration like
UL listing.

Background:
I am doing an electrical project in my house.  I am not an electrician
but I am an engineer and I understand electricity.  The house is from
1937 and I am replacing the knob and tube with Romex (nm) cable so I
can put in insulation.

The problem I have is that the house is plaster and lath.  I do not
want to take out all of the walls because I like the plaster/lath
look.  To save these walls, I am not replacing the electrical boxes
that are there.  These boxes have 5/8" holes.  In some places I cannot
put a larger 7/8" hole, so I am using the 5/8" holes.

I am tired of paying $20 per fixture to get one $1 fitting so I have
not done any work on the project in a long time.  Please help me
finish the project.  It will be much appriciated.

Thanks

---

Clarification of Question by cozmobuchar-ga on 20 Nov 2005 13:23 PST

The clamp that I have found has "sc-01" on the side.  The other side
has "c" backwards R merged with a U (r) reserved symbol and "US".

If you use a staple within 8" of the box, you do not need a clamp, as
long as it is in the wall.

Thanks for the info, vonmeister.