DIYbanter - View Single Post - RMC conduit going into box w/concentric KO's

The Daring Dufas[_4_]

wrote:
I'm using rigid steel conduit with steel boxes where I have elected to
use the conduit as the grounding conductor. I have a 1/2" conduit
going into a masonry box with concentric 1/2 & 3/4 knockouts. I'm not
crazy about concentric KO's so I thought I'd knock out to 3/4 and use
a 3/4 to 1/2 reducing bushing where the conduit enters the box. (In
this case it would actually be an "expanding" bushing.) ... and a
locking nut on both sides of the
connection.

Isn't what I propose better than using the 1/2 knockout then praying
that the 3/4 knockout doesn't come loose? -- better for insuring a
good ground? The code does not say much about reducing bushings. I
really rather not run a separate grounding conductor.

--zeb

Here's a little tip that me and my brother use when
dealing with loose concentric KO rings. We take a
conduit punch and turn it backwards so the flat parts
are on either side of the ring. When the screw is
tightened, the ring is mashed back into place and is
tighter than it was to start with.

TDD