Low Voltage Lighting in Concrete Slab

[LSOL804]

I'm a low voltage (12v - 15v) outdoor lighting installer, and I typically install systems for existing houses. I'm in the process of designing and quoting a large outdoor lighting project for a high-end custom builder who is currently framing a 12,000 sf house. The driveway will be exposed aggregate concrete, and there will be concrete around the pool as well. I want to install small well lights that are flush to the surface of the concrete, which will be used as subtle markers along the edge of the driveway and pool decking, as well as to light the garage door centered on the garage apron. I would typically core drill where I want my fixtures to be, and run my direct burial wire as best I can. I'm trying to think through the logistics of this install prior to the concrete pour. I'm thinking that I should run conduit and somehow stub-up at each fixture location. The housing of the well light is 1.2" wide and 4" deep, while the head that is flush-mounted is 2" in diameter. If I were core drilling, I'd use a bit that is 1-1/4" and go down 5" into the slab, and the wire is 18AWG direct burial. I'm looking for advice that will look professional, both in the finished product and in how I present my company to this builder and concrete contractor he uses. Specifically, what type and size conduit should I use, do I bury the conduit in the gravel, set it between the rebar and vapor barrier, etc., what's the best way to stub it up so I can come back after the pour and easily install/wire the fixtures, etc.? Thanks!

 

[Todd0x1]

What brand lights are you using? The 'better' brands of these lights have concrete pour kits for their well lights which are similar in nature to a concrete floor box. I don't know that I would want to try to stub up conduit (and expect it to survive) and core drill over it later.

 

[LSOL804]

The brand is Garden Light LED (product link). I don't believe they make a concrete pour kit, so I'm trying to think through a makeshift option that will be clean. When you say you wouldn't expect the conduit stub up to survive, would it matter if the stub up cracked and/or fell apart later, since it will just be a sleeve/form for the cavity where the fixture will sit?

 

[brantmacga]

verify the fixture will fit inside a 1-1/4" conduit. Place 1-1/4" PVC conduit before the pour, drop in fixture when complete.

The conduit is just a sleeve, not a complete raceway system.

 

[LSOL804]

verify the fixture will fit inside a 1-1/4" conduit. Place 1-1/4" PVC conduit before the pour, drop in fixture when complete.

The conduit is just a sleeve, not a complete raceway system.

Thanks - I believe the fixture will fit the 1-1/4" conduit sleeve. How would I secure the sleeve to prevent it from moving during the pour? I'm trying to think through the logistics of running the wire to where all the fixtures will be - some along the edge of the driveway and some centered below a garage door on the apron. Does the sleeve need to tie into the conduit for the direct burial wire, or would it be separate? Which type of conduit should be used (ENT, rigid, etc.)? Does this conduit get buried in the gravel base, or should it just go between the rebar and vapor barrier?

 

[brantmacga]

For securing the conduit sleeve I can think of a couple ways:

Drive/bury the conduit stub deep enough in the ground that mild bumping won't disturb the location. You'd need to drill a hole in the side to route your direct-bury cable inside the conduit. Or, you can drive rebar down the center of the conduit, and drill a hole through the conduit above the slab level that allows you to tie it off to the rebar.

If you're trying to do a complete raceway system, you could use a PVC floor box Y adapter fitting (Carlon, Leviton, Hubbell all make them) adapted to the bottom of the 1-1/4" conduit. Make sure it's deep enough your fixture won't hit it and have room for the splices to drop in. Bury that deep enough and it'll hold your sleeve. I used to bend keyway stakes over conduit and bury it in the dirt to help hold stuff in place.

 

[don_resqcapt19]

If the lights will be within 5' of the inside edge of the pool wall, you will need to make sure that the transformer or power supply that supplies power to the lights complies with 680.23(A)(2). This is required because 680.22(B)(6) requires compliance with 680.23(A)(2).

 

[Todd0x1]

The brand is Garden Light LED (product link). I don't believe they make a concrete pour kit, so I'm trying to think through a makeshift option that will be clean. When you say you wouldn't expect the conduit stub up to survive, would it matter if the stub up cracked and/or fell apart later, since it will just be a sleeve/form for the cavity where the fixture will sit?

I was thinking you were stubing up conduits for the wires, not a sleeve to put the fixture in. Disregard my comment.