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.
Article 358 contains the requirements for installing EMT. 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'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.
I usually assume that below grade conduit is full of water and am often right. It seldom causes a problem. Use a type of wire with "W" in the designation, avoid splices, and all will be fine.
I don't know what the code says, but have you considered using rigid conduit instead of EMT? It is more like iron pipe than tubing and uses pipe threads to make connections.
I agree that he should use it BUT it's a BUNCH more $$ now, the conduit prices have gone OUT OF SIGHT!! A 10' of 1.5" ridgid is over $50 at the wholesale supply here in Iowa OUTCH!!!
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 several years.
And it still rusts when in contact with wet concrete floors. Or wet ground
Gunner
"The entire population of Great Britain has been declared insane by their government. It is believed that should any one of them come in possession of a firearm, he will immediately start to foam at the mouth and begin kiling children at the nearest school. The proof of their insanity is that they actually believe this." -- someone in misc.survivalism
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