I want to run EMT conduit along my concrete floor to power my lathe. The
arrangement is such that I'm not worried about someone tripping over it.
But it is possible that water could leak because of a broken pipe, hole in
the roof, etc. and come into contact with the wiring. I plan on using
compression fittings and making the conduit as water tight as I can.
Does anyone know if the national electrical code permits installing conduit
on the floor? I borrowed the 2002 NEC Handbook from the local library, but
I can't find any mention of where conduit should be installed. The book is
1200 pages and the index didn't help. Which chapter should I look in?
Conduit can be and frequently is placed below ground level (mostly plastic
these days), so I can't see a problem with what you propose. There might
be a local requirement for direct burial rated wire, and you certainly
wouldn't want junctions that weren't water proof on the floor if there was
a potential for flooding.
I've had THC in cemented plastic conduit for an underground
conduit approved, but local regulations can be different. I'd suggest
checking with your local inspection department.
The instructions said to use Windows 98 or better, so I installed RedHat.
I second that.
I'm having problems with the fire dept. over code. The bottom line is what
ever the inspector will except. The code is often left up to the inspectors
"interpretation" of said code. It's his way or the high way.
If you have one of those hard-nosed inspectors that likes to jerk you
around, tell him to put it in writing and sign and date it. That can get
them to back off if they aren't enforcing code, but their own desires.
You'd be surprised how often they have no authority to make you do things
the way they want. It's an old ploy those that have an attitude use to run
you in circles. Once they sign it and it's not necessary for code
compliance, you have them in your palms, assuming the local government isn't
totally corrupt. That's something I learned from an old acquaintance that
worked as a wireman for the majority of his life.
Sounds like a good way to make an enemy you don't need on
the off chance you might be able to get his ruling changed.
Here's what the NEC has to say,
"The authority having jurisdiction for enforcement of the
Code will have the responsibility for making
interpretations of the rules, for deciding on the approval
of equipment and materials, and for granting the special
permission contemplated in a number of the rules."
It is _always_ appropriate to ask for a statement in writing--it eliminates
potential for future misunderstandings. Any inspector who has a problem
with writing down his interpretation is already your enemy. Just ask him
politely and make it clear that you want to have it down so that you don't
forget something important later.
Reply to jclarke at ae tee tee global dot net
I would be concerned with 358.12(1) which states that
EMT is not permitted in areas subject to severe physical
damage. That right there would cause me to run IMC or
RMC on floors.
To take care of the water, make sure the wire you use is
listed as THWN. Table 310.13 has all the types of wires
and where they can be used.
I worked with a company a few years ago that allowed you to do most anything (when
you ran wire) as lone as the first device,
terminal or connection was 18" above the floor line. Seems they had floods from time
to time and if the first opening or
connection was above the water level, you could treat it as you would any other wire
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)
A possibility you might look into to get you around elctrical codes is
a more elaborate form of extension cord. In other words a good robust
length of cab-tyre covered where it crosses the floor with some of
that heavy duty poly cable protector used in computer rooms. The size
you would need is about an inch and a half high and four inches wide,
formed like a very shallow inverted U. You glue it to the floor with
silicone and it will protect the cable, minimize the probability of
your tripping over it and allow equipment like welding carts to be
wheeled over it without trouble.
Tell that to the people who try to bury EMT outside - that
galvanized coating won't last long at all in constantly wet
conditions. I have two buildings that let amateurs do their repairs
and are going to have to dig up 250'+ each of EMT buried about 3" down
under the lawn...
(One was the pool man redoing the pool lights wrong, and the other
was the original developer cheaping out on the outside lighting.)
EMT should be fine going across the floor of your shop to the
machines as long as it's not constantly wet, and running from the wall
behind the machine - not across a normally accessed aisle and
presenting a tripping hazard.
We're talking about a home shop, you don't need to make it
thoroughly bulletproof like you would in a commercial shop. For a
business, you'd cut and trench the floor and place PVC conduit under
the slab to each machine location, and convert to a Rigid coupling (or
place a rated floor box) where it pokes through the floor...
The suggestion to make the conduit one-piece across the floor (down,
across, and up with one stick) is a good one, because even raintight
couplings will leak if they are submerged - and the normal cast-zinc
couplings break easily if they get any sort of abuse, which would let
moisture inside easily. If you can find them, get the steel fittings.
Use THWN wire in the pipe, even if it gets wet it will last for
--<< Bruce >>--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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