Running UF cable through concrete

[Dave Zellers]

Is it ok to use PVC inside the concrete to house the wire or does it have to be that gray tubing that is made for electric cable?

This is outdoors and the concrete will be a sonotube for the base of 3 post lights.

[Aaron Rosenthal]

Not an electrician, but when I wanted to run cabling underground from the house to the garage workshop, my electrician insisted on the proper conduit PLUS the yellow Danger tape.

[Frank Pratt]

Underground wiring is very commonly run in gray PVC conduit. Care must be taken to use appropriate bedding in rocky soil to prevent damage to the conduit. You do not want to run conduit outside in a concrete sidewalk because any movement at the control joints will break the pipe. I did a service call to check out some pole lights that weren't working. The conduit had been run in the sidewalk & I just happened to hear the arcing through the crack in the sidewalk.

[Charlie Velasquez]

Is it ok to use PVC inside the concrete to house the wire or does it have to be that gray tubing that is made for electric cable?

This is outdoors and the concrete will be a sonotube for the base of 3 post lights.

Electrical conduit must be listed, hence the electrician in Aaron Rosenthal‘s post requiring the proper conduit.

Also
If your plan is to stub out a piece of pvc then add a weatherproof junction box to supply the light and to supply an outlet or such, consider:
Conduit that houses the conductors can not be used to support a box. That is why you may see those types of installations with two pieces of conduit, one for support and one for the conductors.
Edit: if this is your plan, you need to install the box at the time you run the conduit. The box must have threaded hubs. Since it requires two conduits, you can’t add the box post hoc as you could twist the box on one stub, but not both at the same time after the concrete sets. (NEC 314.23 discusses securing boxes)



For outdoor use not protected by backfill or structure, some inspectors require schedule 80 conduit for the exposed part of your stub out.

Uf is wider than nm. @423 mils for 14-2 with ground, and 463 mils for 12-2 wg. So, the 14-2 would fit in 1/2” sch 40, but not sch 80.
12-2 would need 3/4”.

[Dave Zellers]

Thanks guys- I figured as much but thought I should ask. I guess I should turn this job over to an electrician.

[Charlie Velasquez]

Thanks guys- I figured as much but thought I should ask. I guess I should turn this job over to an electrician.

Still doable. Get away from just using the stub. Run the stub a few inches high, drill a hole in a piece of cedar or redwood, or treated, or that simulated wood made from pvc.
Secure the wood to the concrete luminaire base, secure the box to the wood (using some sort of gasket- common in weather resistant box kits) , bringing the conduit in from the bottom.

Most light posts are hollow in the middle and will fit over your pvc stem.

Think out you plan, draw it out, take it to you local Authority Having Jurisdiction, get his/her opinion.

[Dave Zellers]

Still doable.

Thanks for this reply! I am more than capable of doing this, I just want to do it right. One thing- the UF cable is already 2 feet in the ground (no conduit), buried with loops that come up through the ground and back down to the next location along with CAUTION! tape buried at the 1 foot level. I did it possibly 20 years ago and now I want to finish it. I just don't want any concrete in contact with the UF cable so I thought I would heat and bend a large 90º in some PVC and bring the wire up through that inside the concrete and thus, inside the post.

Yes, the lamp post is hollow aluminum and I expected to make all the connections inside that.

Let me make a drawing and post that. Cool! I shudder at the thought of what an electrician would want to do this.

Paying my plumber is painful enough.

[Dave Zellers]

If the gray electrical conduit is PVC also, will it bend with heat in the same way as plumbing PVC?

If so, I have no problem using electrical conduit, assuming it has unique qualities for wires. Or even if it is required.

[Paul F Franklin]

The gray pvc conduit will bend as easily as PVC, although it is easy to buckle it while bending. You could buy a sweep 90 El and solvent weld it to a straight piece as an alternate. The gray PVC has UV inhibitors in it that help prevent it from degradation by exposure to sunlight.

[Dave Zellers]

Thanks Paul for that. I knew it had to be something like that.

Attached is a drawing of what I am looking to do.

444023

[Dave Zellers]

Bending PVC is easy- make a form, use a heat gun and go slow.

But I will look into Sweep 90's.

[Dave Zellers]

Sorry for the flurry of posts- I think at this point my biggest question is- why can't I make my wire nut connections inside the aluminum posts.

I'd be fine with encasing them in shrink wrap tubing.

[Paul F Franklin]

Any splice should be accessible. If there is an access plate on the post then you can position the splices behind that. Or if the receptacle will be mounted low on the post (should have an in-use cover) you can make the splices in the box for the receptacle. Or you could add a weatherproof box low on the post and spice in that. Since your cable is already run you don't have the option of making the splices up in the lamp head. If you have no choice but to make the connections in the post, just do so knowing that servicing them will require pulling the post and make the best connections you can. An inspector probably wouldn't pass that approach, if that's of concern.

[Dave Zellers]

If you have no choice but to make the connections in the post, just do so knowing that servicing them will require pulling the post and make the best connections you can. An inspector probably wouldn't pass that approach, if that's of concern.

Anything that would not pass inspection is of concern to me. It's why i'm here asking all this. But to note- Both the base of the post AND the lamp head would be removable and accessible at any time going forward. The lamp post is NOT incased in the concrete, a base is attached to the top of the concrete and the post fits inside that. So there will be a wire nut connection at the base and another at the top of the post. Both accessible at any time. This has to be OK. ! No?

[Charlie Velasquez]

As long as any splice, termination, or connection is easily accessible.

Couple of things,
The AHJ may require a bushing on the end of your pvc where the uf cable enters the conduit below grade. Always required on rigid, the AHJ has leeway on PVC
Wrt bending vs elbows:
NEC (2017) Rigid PVC
352.24 Bends — How Made. Bends shall be so made that the
conduit will not be damaged and the internal diameter of the
conduit will not be effectively reduced. Field bends shall be
made only with identified bending equipment. The radius of
the curve to the centerline of such bends shall not be less than
shown in Table 2, Chapter 9.
That said-
In my job I worked with a number of electrical contractors. I can’t remember any of them having a listed bending equipment for pvc, all of them had a heat gun.
3/4” is easier to bend than 1”, 1/2” is easier than 3/4. If 1/2” buckles it is ruined, you have no leeway. 3/4” probably still gives room for 14awg uf.

You’re only going up 24” through one bend, with 14awg. Consider 3/4” and consider the sweeps suggested by Paul Franklin.



If any connections are made in the post, the aluminum post must be grounded. Some inspectors consider being attached to concrete with bolts as being grounded, some want a separate ground.

I am assuming you are going to run your uf to your outlet at the base. Uf is terrible to work with so assuming you are going to run thwn from the outlet to the light at the top. Look for ways to support the wires from the outlet box to the luminaire at the top of the post. No one I know has failed an inspection for unsupported wire inside a post, but what the heck...
These are some things for which an inspector has discretion. Always a good idea to check.

Because you went 24”, you can gfci protect your circuit at the panel, at your first connection and downstream, or pigtail and protect each pole separately. I like the individual protection. If you have a fault, it won’t affect the rest of the lighting or outlets, the reset button is right there, and you’ll know which area is causing the fault. It will also make wiring the outlet easier. Strip 3/8” off conductors in your two uf cables, insert into a wago connector, add a 14awg thwn pigtail to the line of the gfi, then thwn from the load of the gfi to your light. May want to add a bare/green to the ground wago if you can find a place to ground the post, They make a barbed grounding clip that slides onto any like 1/16” flat protrusion, but be careful of dissimilar metal. they are rated for steel boxes, not sure of aluminum (noalox??). Whether wagos or wire nuts, keep the wires below the connections so any moisture/condensation runs away from the connection.

[Charlie Velasquez]

Anything that would not pass inspection is of concern to me. It's why i'm here asking all this. But to note- Both the base of the post AND the lamp head would be removable and accessible at any time going forward. The lamp post is NOT incased in the concrete, a base is attached to the top of the concrete and the post fits inside that. So there will be a wire nut connection at the base and another at the top of the post. Both accessible at any time. This has to be OK. ! No?

A commercially made post and lamp?
Already wired to the light and fed to the base?
Access at the base for your uf?

Just follow the instructions, the lamp post is an approved junction box location. Would still go the way of Wagos and individual gfci protection.

[Dave Zellers]

... the lamp post is an approved junction box location. Would still go the way of Wagos and individual gfci protection.

Very good. Thanks for your help- much appreciated.