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-   -   Wire size and type in Rigid Metal Conduit (http://www.diychatroom.com/f18/wire-size-type-rigid-metal-conduit-16632/)

Al the Diy guy 02-05-2008 09:10 AM

Wire size and type in Rigid Metal Conduit
 
Greetings most educated ones....


I have a run for two 120v 15a GFIB protected receptacles that comes out of the main, through the wall (22 inches) exits the structure, comes down the exterior wall (5ft) enters the trench and goes 50 ft to the first receptacle then an 40 more feet to termination at a 120v receptacle.

So far I have the following; out of the main with ENT to LB conduit body via threaded PVC adapter. So here are my questison

1. I need to go out of the conduit body straight for 2ft then 4ft down into the trench. Can I use liquid tight to come out of the LB make the curve down and then tie into my Rigid Metal Conduit run with a 90 deg RMC Sweep. Or do I have to us RMC out of the LB and cut and bend it. (the problem here is no bender (yet!, but perhaps I can get a kitchen pass to go get one)

2. I was thinking 14 awg THHN/THWN (black, white, green) is this right or should I use 12?

3. Since I have the GFIB is there any adddional protection afforded by putting in GFI recpetacles or does that not improve safety in any way.

Thank you o' knowledgeable ones.....DIY AL:eek:

convertedbird 02-05-2008 09:29 AM

Why don't you use pvc, skip the metal in trench and put 12 ga wire in it. If you are puting in a post for a camper or pluging in a diesel truck go with 10 ga or even if the need comes up latter you have the wire in to do it.

Al the Diy guy 02-05-2008 10:17 AM

ConvertedBird, not sure yet if I can get deep enough for PVC, possibly, I need 18" for other than rigid metallic conduit (I think, I will check back with the inspector as this is under a concret pool deck I may be able to go shallower). so far the trench is down to 12". These are convience recpticals around my pool.:pinch:

HouseHelper 02-05-2008 10:24 AM

If it is a 120V, GFCI protected circuit, the minimum depth would be 12-in; or 6-in under 2-in thick concrete; or 4-in under 4-in concrete in a raceway.

Al the Diy guy 02-05-2008 11:05 AM

Quote:

Originally Posted by HouseHelper (Post 95129)
If it is a 120V, GFCI protected circuit, the minimum depth would be 12-in; or 6-in under 2-in thick concrete; or 4-in under 4-in concrete in a raceway.


Thanks, It is going under 4 in concrete but on the way is goes under 1.5" concrete pavers so I would think 12 inches under the paver section then as little as 4 inches under the cement deck. Now....can I run 3/4' LFMC (liquid tight) the from the LB Conduit body to terminiation? :no:

goose134 02-05-2008 08:31 PM

Two things. One, you can buy pre-made threaded 90's for rigid. Second, it's really hard to kink rigid and you can bend it (in a pinch) in the fork of a tree. I did my neighbor's garage feed and had to put a 30deg. kick in a 1" rigid, but I didn't have an 1 1/4" bender.

Shorter answer- If I read you right and the LB is above grade, you can run seal tite.


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