Replacing liquidtite conduit

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Old 07-07-16, 06:46 PM
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Replacing liquidtite conduit

I am replacing the liquidtite conduit that goes from my pool sub panel to my spa blower. The existing conduit is 3/4" and has 3 12awg wires inside. I noticed that there is also 1/2" conduit. Does it matter which size I use?

As far as the wiring, do I have to buy each wire separately (i.e. hot, neutral, ground)? I know that I need to use thhn/thwn. It doesn't look like they make 12-2 thhn in the length that I need (about 20 ft). I also realized that all of the hot wires for my pool equipment are red (not black). Is there any particular reason for this?

I was going to buy everything by the foot at Lowes. They sell it in bulk, apparently. Are these products okay (see below)?

THHN: Shop 12-AWG Solid Black Copper THHN Wire (By-the-Foot) at Lowes.com

Liquidtite: Shop Liquidtight Flexible Non-Metallic Conduit (LFNC) (By-The-Foot) (Common: 1/2-in; Actual: 0.5-in) at Lowes.com
 
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Old 07-07-16, 07:14 PM
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My first question is why do you wan to replace it?

It is best to install individual conductors when using conduit. In your case it is not allowed to a bare ground like you would find in UF or NM-b cable so you are required to use an insulated ground.

I would not recommend using 1/2" non-metallic flex. Pushing the conductors in will be a HUGE pain in the butt! LFMC is a better option or up-sizing to 3/4" will also allow you to use the same knock outs.

I also realized that all of the hot wires for my pool equipment are red (not black). Is there any particular reason for this?
No. Any color may be used for ungrounded (hot) wires except white, gray, or green with ot without stripes.
 
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Old 07-07-16, 07:29 PM
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Thanks for your post. I would prefer not to replace it, but I don't think I have a choice. The existing conduit is too short to reach my new blower. You can see my original post here: http://www.doityourself.com/forum/el...too-short.html

Am I able to insert the wires before I install the new conduit? Or, do I have to push the wires through the conduit after it is buried?

I just wanted to clarify…Are you saying that it would be easier to use metallic conduit (instead of NM)?

Thanks again for your help.
 
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Old 07-07-16, 07:32 PM
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Lowes offers a pretty good selection of #12 stranded wire by the foot.

For 120v pick a color, a white and a green.
For 240v pick two colors and a green. (the colors can be the same)

Shop #12 stranded copper wire by the foot at Lowes
 
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Old 07-07-16, 07:40 PM
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PJ, I was under the impression that I should use solid wire. Is that not accurate? If not, what is the reason that stranded is used? Sorry for the followup questions.
 
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Old 07-07-16, 07:46 PM
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Stranded is easier to pull and work with. Sometimes the writers of instructions write the rather ambiguous phrase "solid copper wire" when they really mean no aluminum wire or copper clad aluminum wires.
 
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Old 07-07-16, 08:04 PM
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You could install a weather proof box on the end of the conduit (properly supported and correct fittings used) It would also be a good place to install a disconnect if needed. Then you would need a very short piece of conduit and wires. Your could also couple a short piece of conduit on (using the correct fittings) and just repull the wire too.

Are you saying that it would be easier to use metallic conduit (instead of NM)
Yes. Liquid tight Flexible Metal conduit. IMO - If I was replacing the run I would just use 3/4" PVC (the gray stuff) It would be cheaper.

Am I able to insert the wires before I install the new conduit? Or, do I have to push the wires through the conduit after it is buried?
Technically you are required to have the conduit installed complete and then install the wires.
 
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Old 07-07-16, 08:11 PM
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Technically you are required to have the conduit installed complete and then install the wires.
But they sell ready made whips so I'd consider that a bit of a gray area. Where that rule is most important is with conduit glued with solvent cement. An easy work around to stay out of a gray area is install a pull string as you assemble.
 
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Old 07-08-16, 05:25 PM
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But they sell ready made whips so I'd consider that a bit of a gray area.
True, but ready made whips are typically no longer then 6' such as whips for A/C units and light fixtures in a suspended ceiling.
 
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Old 07-08-16, 05:46 PM
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With a 90 degree connector, you need to pull the conductors and then feed them through the 90's.
 
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Old 07-08-16, 10:07 PM
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Tolyn, I like your suggestion about using a coupler or a weatherproof box. Unfortunately, I am going to have to re-run the entire length. I accidentally left the conduit and wire exposed (power completely off). We had a lot of rain this evening, and I forgot to reattach the weatherproof box. I can't believe that I did that. I'm thinking about just hiring an electrician to do the work. As a side note, what is the burial depth requirement? I see references to 18" for PVC, but I don't see much on LFNC/LFMC.
 
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Old 07-08-16, 10:10 PM
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The wire is intended to survive a little water. Conduit outside is considered a wet location and buried conduit sometimes fills with water.
 
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Old 07-08-16, 10:46 PM
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The wire is intended to survive a little water. Conduit outside is considered a wet location and buried conduit sometimes fills with water.
That is really good to know. I never realized that water sometimes fills the conduit. I assumed (incorrectly) that if that happened, the wire/conduit would be ruined.
 
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Old 07-09-16, 07:36 AM
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How do you properly join two pieces of LFMC? All of the couplings that I see are rated for LNFC only. Also, is there a specific tool for cutting metal conduit?
 
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Old 07-09-16, 07:37 AM
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If it is metal inside it will likely rust but this happens all the time. The conductors will be fine. I would try blowing it out with compressed air to eject as much water as I could.
 
 

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