LFNC v PVC - Liquidtight Conduit for from junction box to lamp

familytr33

Bronze Supporter
Apr 4, 2016
81
South East USA
Hi,

I'm re-locating a junction box which runs to a lamp in a wet niche.

I'll be splicing into the existing conduit from the lamp.

The run form the jbox to the niche will be about 50 feet.

I considering 3/4 liquid tight flexible non-metalic conduit (LFNC-B, not LFNC) buried at 18 inches under packed earth for ease of use.

PVC is certainly a lot cheaper. Are there any other benefit of using PVC over LFNC?

Thanks,

ft.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,218
San Clemente, CA
That conduit is not permitted for burial. If it was, I would not suggest using it anyway.

PVC conduit can be relatively easily bent or shaped. There are several tutorials on YouTube.

I highly suggest using 1" conduit, it will make pulling the cord that much easier.
 

gwegan

TFP Expert
Apr 19, 2013
2,769
Sacramento, CA
Yes there is a benefit of using regular non metallic conduit over liquidtight. First, you can generally only bury liquidtight if it say you can. It must be listed and marked for that purpose. So look on the liquidtight it will say "direct burial."

Next you need to understand that the conduit from the light niche to the junction box is special. It is designed to be wet and it is expected that at some point you will have to replace the fixture. and re run the cable. So it should be oversized, 3/4 minimum so its easy to pull through the cable and a separate ground.

Finally most liquidtight is not used for long runs, its rough. Its difficult to fish wires through it if you are trying for a long run. Homeowners tend to allow it to bend and twist which adds to the difficulty in fishing wire.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,866
Sebring, Florida
I will add a big PLUS 1 for using oversize conduit. Pulling a 100' wire through a 3/4 inch conduit mess I made for myself nearly brought me to tears.
 

bdavis466

TFP Expert
Platinum Supporter
Aug 4, 2014
5,218
San Clemente, CA
This is in a flooded application where it would be difficult to connect to the niche out existing pipe without having a leak.

Its expensive and the benefits do not outweigh the disadvantages in this case.
 

gwegan

TFP Expert
Apr 19, 2013
2,769
Sacramento, CA
Most industrial electricians don't use LFNC-B for long runs if they don't have to. Its expensive and I don't see someone without a lot of experience having a reasonable time pulling that much through it.

It comes in rolls that can be difficult to get straight.
 

jason176

Active member
Apr 3, 2016
39
Kankakee Il
I actually had to google it to see what it looked like. My take on something like that is if it Flexes, it has to give up some strength to do it. Would you rather a pool builder use rigid PVC or flexible PVC for plumbing? Is it acceptable, maybe, but why chance it? Rigid PVC has the tendency to pull really difficult with certain types of insulation, just use a little Aqua lube and it will pull like butter, also steel 90's help too. Almost forgot, a propane torch or weed burner can be used to bend it, they make special springs to use with a pipe bender, but that means buying extra stuff.