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-   -   Running cable in conduit (http://www.diychatroom.com/f18/running-cable-conduit-122726/)

Audiotekm 11-07-2011 09:22 PM

Running cable in conduit
 
I have to run about 75feet of 12/3 into a 1/2inch PVC conduit for outdoor purposes. I've already trenched the path %60 straight line and %40 zigzagging I have a combination of solid PVC and flex tubing.

1-My question is should I run the cable into the conduits right now section by section and cement the joints?

2-Cement all the joints and run the cable with a fishing tape?

Option 1 would be easier but I'm wondering if I could run in any complications!!!! I've always fished cables since the conduits were already installed but since I'm installing the conduits maybe option 1 would work!!!!

jbfan 11-07-2011 09:36 PM

You can not install the cable into the conduit a peice at a time.
You can not use nm-b cable outside.
You will never be able to pull 12/3 through 75' of conduit and flex anyway.

Audiotekm 11-07-2011 09:47 PM

What kind of issues would I run into if I run the cable inside each piece of conduit?

And why I can't run NM cable inside a conduit? It's a 15A circuit to run some LED Xmas light in my backyard garden. The lights probably will draw 3~5A


Here's the cable i got... for free Carol 12/3 Type SJ FT2

brgmgb 11-07-2011 10:18 PM

Quote:

Originally Posted by Audiotekm (Post 766203)
What kind of issues would I run into if I run the cable inside each piece of conduit?

And why I can't run NM cable inside a conduit? It's a 15A circuit to run some LED Xmas light in my backyard garden. The lights probably will draw 3~5A

Why can't you use a larger size conduit? 12/2 fits better in 3/4" conduit, but with the zig zags, I'd even go to 1". Since the trench is still open, I'm not sure why jbfan says you cannot install the conduit one length at a time.

As said, you cannot use NM Romex. You can use UF which is rated for wet conditions. NM is not rated for wet conditions. The inside of buried conduit is considered a wet condition. Just as pipes sweat in your basement, you will get some condensation in the conduit.

iminaquagmire 11-08-2011 12:53 AM

Type SJ cable is not meant for permanent fixed installation, let alone in conduit and underground. Your conduit needs to be at least 18" deep with type THWN wire used. You also need the appropriate connectors for transitioning to your flex which should be liquidtight conduit. You'll never get UF cable into 1/2" PVC.

mpoulton 11-08-2011 03:24 AM

Quote:

Originally Posted by Audiotekm (Post 766203)
What kind of issues would I run into if I run the cable inside each piece of conduit?

And why I can't run NM cable inside a conduit? It's a 15A circuit to run some LED Xmas light in my backyard garden. The lights probably will draw 3~5A


Here's the cable i got... for free Carol 12/3 Type SJ FT2

The NEC requires that conduit be fully assembled before the conductors are pulled into it. The basis for this is to avoid damage to the conductors during assembly, and to ensure that the conductors can be removed from the conduit assembly later if needed. With that said, people do sometimes assemble conduit with the conductors in place. It's not code compliant and it usually ends up being harder to do than pulling them through later, even though it seems like it will be easier.

NM cable is not permitted in wet locations, and buried conduit is a wet location. Not just according the the NEC, but for real. Buried conduit ALWAYS becomes very wet due to condensation. NM cable falls apart eventually in contact with water.

The cable you have is not usable for this application. It is not code compliant for use in conduit or in any concealed application at all. It is also not water resistant. You need THWN. You should be able to pull 4 THWN #12 conductors through 1/2" with no problem if you use plenty of lube and don't have more than 360 degrees of total bends in the conduit (the code limit, and the practical limit as well). Your conduit needs to be 18" deep, or 12" if you use GFCI protection.

ddawg16 11-08-2011 12:16 PM

Audio....dude.....listen to the above advice.

I hear where your coming from.....many many years ago I would have been wanting to do the same thing. Ever hear the phrase "You learn by your mistakes". Well.....that is why I'm so bloody smart.....

You will NOT be able to pull that 14/3 NM (Romex) through the 1/2" PVC....you can try....you might make it 25'....and if you lube it up real well...maybe 50'.....if you have more than 2 bends....I know I could win a $100 bet real easy....

I bet all the wire pulling you did was with stranded THHN....a lot easier to pull than solid 14/3....even if you remove the jacket from the 14/3, it's going to be hard to pull...solid wire does not pull very easy through PVC conduit.

When ever I'm sizing conduit...what ever size I think I need....I then bump it up one size. And in the end, I'm sometimes wishing I had gone even larger.

Audiotekm 11-09-2011 09:35 PM

I bought 85feet of NMWU 14/2 for $40 I laid out the conduit path what I will do is I will straightened out all the conduits and run the cable I don't even think I will need to fish it the cable is pretty thin.

Jim Port 11-09-2011 10:47 PM

Based on your description of the cable I am going to guess that you are in Canada. Under the NEC in the US NM cannot be used outside, even when in conduit. I think the CEC has a similar prohibition. You need to run individual conductors or change to a cable suitable for use outside.

jimmy21 11-09-2011 11:20 PM

Quote:

Originally Posted by Audiotekm (Post 766180)
I have to run about 75feet of 12/3 into a 1/2inch PVC conduit for outdoor purposes. I've already trenched the path %60 straight line and %40 zigzagging I have a combination of solid PVC and flex tubing.

1-My question is should I run the cable into the conduits right now section by section and cement the joints?

2-Cement all the joints and run the cable with a fishing tape?

Option 1 would be easier but I'm wondering if I could run in any complications!!!! I've always fished cables since the conduits were already installed but since I'm installing the conduits maybe option 1 would work!!!!

Flex tubing does not belong in your application at all

darren 11-09-2011 11:46 PM

Quote:

Originally Posted by Audiotekm (Post 767584)
I bought 85feet of NMWU 14/2 for $40 I laid out the conduit path what I will do is I will straightened out all the conduits and run the cable I don't even think I will need to fish it the cable is pretty thin.



NMWU is wet rated cable. If you have NMWU why don't you bury it directly in the ground and use PVC sleeves where you come out of the ground. Skip the pipe all together.


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