I am installing a 120v water heater in a 208/120 breaker box. Oddly, there
are no knockouts. Is that common in 208/120v?
I see three options; your advice on their legality would be appreciated.
1) I can cut a hole with a hole saw. Not a pleasant chore, but possible.
2) There is an outlet in a box just below the breaker box, connected to it
by a 1/2" conduit. I could connect my MC cable to the outlet box and run
the wires into the breaker box by the 1/2" conduit. I presume 1/2" conduit
can take two sets of #12 cable.
3) I can run my circuit to the outlet box and attach it to the wires that
feed the outlet. The outlet is only used for a radio and the water heater
is only 13a, so there should be plenty of capacity.
More than one wire can go through a single knockout.
If your wire will not fit through an existing one, relocate one of the 110v
to create space.
This option is 100% legal. The others I have doubts about.
I missed that part of the post. Sorry.
The other posters have good suggestions.
I would have to wonder why everything is in conduit. Is the a commercial
building? Or a Condo type project?
Conduit may be a requirement for certain structures and locations.
Are they all in use? Sometimes when I have to cut open a wall to pull a
wire I add some empty conduit sections to the panel box for future use. I
cap both ends to prevent critter entry.
Try a rental center for the proper tool. It sounds expensive.
It is common for industrial equipment to come without preformed KOs.
Industrial electricians have KO punches and poke a hole where they
You can get the wrench powered ones at a good home store. Drill a 3/8"
hole, assemble the cutter and die on each side and tighten it up and
you cut a clean hole.
The much maligned Harbor Freight has a manual KO punch set rather cheap
that would probably do the job. They also have a hydraulic driver
There is also the option of the Greenlee KO sized step bit, which is
what I use for the small number of times I need to make holes in pull
boxes and whatnot.
The question w/ HF is will they last a single use??? :)
IME it's been a crapshoot...some stuff is amazingly good for the price;
some is pure junk. The problem is there's almost no way to tell a priori...
Since there's no local outlet, I've pretty much given them. Doesn't
mean anybody else needs to take the advice, I was simply making a
(mostly) lighthearted aside...
Yep, which is why having a HF retail store nearby where you can see the
items in person is a huge benefit. There are a number of gems in their
lineup, as well as many more perfectly serviceable for home shop use
I still don't know why. To use a 1/2" KO greenlee punch, you have to drill a
hole practically that large to fit the bolt through. You may as well use a
7/8" hole saw. Drill once and you're done... and it's cheaper
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