I just bought a new heater for my garage, but all the electrical knockouts
are sized for 1/2" conduit. I need a hole for 3/4" conduit to accomodate
the size of my power cable.
My first thought was to use a knockout punch, but good golly those things
are expensive. I don't want to spend $60 for a one time task like this. I'm
also curious if a punch would work for enlarging an existing hole?
Another option is a step-drill, but those are almost as expensive at the
home centers. I'm also a little worried about metal shavings falling inside
the heater, or overshooting the size I need and making the hole too big.
I haven't had time to check, but I wonder if anyone rents the knockout
You might find a set of used KO punches on Ebay for a decent
price. I knew a guy years ago who used a hole saw. Metal shavings
weren't a problem for his work. It wasn't a super neat job either. The
saw would wander a bit if I recall correctly.
I have a Fahrenheat FUH54 space heater, not a water heater. I have full
access to both sides of the opening.
I just wonder how well a punch will work only having an extra 1/8" on each
side of the existing opening.
On Saturday, February 22, 2014 11:03:51 AM UTC-5, philo wrote:
Except that from what is described, there is no
box to replace. The NO is on a *heater* he's trying
to connect. I suspect he has a *cord* that's too big.
An option might be to install a box and transition from
the cord to 1/2" liquidtight, etc that will fit.
On 02/22/2014 10:32 AM, email@example.com wrote:
Good point and now that I think of it the answer by "Caulking-Gunn"
might actually be the best...to simply use a transitional fitting.
Half inch hole, 3/4" conduit such things exist and would make it a
*I seem to recall a tip from one of the trade magazines. Try clamping a
piece of wood behind the hole and use an 1 1/8" hole saw to enlarge it. I
haven't tried this. Please post the results if you do.
You might find a rental place that has knockout punches.
After considering multiple options, I remembered I had a metal nibbler in
my tool chest. I wasn't sure if it would handle the sheet metal on the
heater, but it worked fine.
You can see the full process with pictures at:
I only have 8 pipe clamps (four feet long),
12 Jet parallel bar clamps (two feet long),
and 12 small bar clamps (one foot long).
It sounds like a lot, but I frequently run out of clamps when gluing up
panels, cabinet doors, or similar projects. I usually have to do my glueups
in stages over two or three days.
I started out with the pipe clamps, and still use them for larger projects.
They also came in handy for construction projects when I needed to pull
walls into alignment or something.
These days I prefer to use the Jet clamps when I can.
I don't use the small bar clamps as often, but when I need them they're
great to have. They have been most useful when gluing up curved objects
like bent wood laminations.
I would love to have more clamps, but I don't know where I would keep them.
Ironically, I still don't have a band clamp. I need to get one of those.
I bought a couple of pipe connectors, but so far haven't used them.
The last time I needed to do a long clamp, I just ganged up three pipe
clamps so they pulled on each other in series. It was quick and easy, so
that's the approach I took. :)
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