14-2UF Ungrounded Through 1/2" Rigid Metal Conduit

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Ravenvalor

Ravenvalor

Senior Member
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Piedmont region of NC
Hello,

Will there be any negative repurcussions if I were to install ungrounded 14/2UF cable through a 70' run of 1/2" Rigid Metal Conduit? The conduit will be 6" below grade in a homeowner's front yard. It will be feeding 6 - candelabra lamps in post lights. My concern is current being induced into the conduit however the total load is only 50-watts max.

Thanks,
 
Probably be a tuff pull, UF cable does not pull well in conduit. Shouldn’t be any current induced because it encircles all of the conductors, probably need to bond the conduit at one end though if your just using it as a sleeve.
 
Induction won't be an issue for the same reason GFCIs don't trip under normal conditions.

Agreed you should bond it at one end, preferably the house end.
 
Use 3/4 conduit. Rigid is rough inside & UF is very stiff, with tacky surface. Lube well & it should pull ok. Bond at one or both ends.
 
If using the RMC as a raceway you would need to figure the fill based on the cable as if it were round. I'm guessing that the 1/2 is "technically" too small but for a straight pull with no bends it will probaly fly in.
 
I missed that. I would not rely on the conduit as the sole EGC.

I recommend pulling individual conductors instead of cable.

Last one I did I pulled four #10s in a 1/2" RGS to the shed.
 
Little Bill said:
Where did you get ungrounded UF wire and why are you using it?
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The house is probably 60 years old and the uf cable feeding the light post/column is probably that old as well. I cannot get into the light post/column because it is 24" wide x 24" wide x 60" high probably solid brick and cinderblock. The column rests on a footer that I do not want to dig beneath for fear of destabilizing. It has a 3" post inside of it that was the original post which probably extends into the ground about 3' within its own concrete bed. After looking at this I decided it might be easier to tap into the old 2-wire ungrounded uf cable feeding it before it even reaches the post/column.'

I was thinking about individually sliding pieces of 1/2" rigid over the new uf cable. There are not any grounds available to ground the metal rigid though. I would not mind using a GFCI somewhere but am worried about the total distance of the entire run = 250' causing nuisance tripping.

Thanks for the help...
 
If there is no way to get at the post to run new cable, worrying about a ground is pointless. You are repairing what's there and there is no way to upgrade. That's all you can do.

Is the existing cable damaged and you have to replace a section? I also don't know why you are running this in conduit. Is it because you don't want to go deeper than 6"? I'm also confused as to why you would limit yourself to 1/2".

-Hal
 
The reason that I was hoping to use metal rigid was to avoid having to find several several buried lines and utilities. Just dig 7".
The reason that I was hoping to use 1/2 was to keep the price down.
I spoke to the inspector and he said that there is a FPN somewhere (he could not pinpoint where) in article 250 that forbids the use of ungrounded rigid in this application.

Thanks...
 
I know industrial (what I mostly work in) is worlds apart from residential, but we try to avoid 1/2 RMC 99% of the time. It is so small. Internet price of 3/4 RMC as 3.11/ft and 1/2 RMC as 3.01/ft. Since you have 1 run of 70ft long I would seriously considering upsizing. Although of course if it is just straight runs and you're going to feed it in 1 stick at a time 1/2 may be fine. I pulled 12/2 UF through 1/2 PVC once (stupidly) and it was a bear...
 
Ravenvalor said:
The reason that I was hoping to use metal rigid was to avoid having to find several several buried lines and utilities. Just dig 7".
The reason that I was hoping to use 1/2 was to keep the price down.
I spoke to the inspector and he said that there is a FPN somewhere (he could not pinpoint where) in article 250 that forbids the use of ungrounded rigid in this application.

Thanks...
Click to expand...

A "FPN" can't forbid anything, they're not part of the code, just information.
 
If the conduit ends and the uf runs thru it with no jb then IMO it is a sleeve. Where is your equipment grounding conductor?
 
We're still discussing this? Read post #7 again and send me a check. :cool:

Ravenvalor said:
Correct, I am tapping into a 50 year old ungrounded 2 wire UF cable. The nearest ground is about 100' away at the home.
Click to expand...
I wouldn't. Run a new cable the whole way.
 
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