I Can't use PVC where I'm at, (Galvy Only!)but out of town in other cities in my area... Direct burial romex, sleaved with PVC, or just PVC all the way. Then, I dig, ( Or, should I say, have some of the generals guys dig. )a post hole at each light location. Mount my box to a pressure treated 2x4, with a 45 at the top. Looks nice, like it was supposed to be there! Then have the general fill the post hole with concrete, around the 2x4, and the sleeve or conduit. Once the concrete is dry, it is a solid unit! Sounds like a bit too much, but practically in-destructable. You have to run over it with a truck!
But, to answer your question. You still need to support the box, and it depends on what is allowed in your area. Call your Inspector.
Mark Heller "Well - I oughta....." -Jackie Gleason
Re: Landscape Lights In Pvc#85542 11/06/0305:56 AM11/06/0305:56 AM
Ron if you want to support a box holding a fixture with the raceway it must be with rigid and you must follow the rules of 314.23(F)
314.23(F) Raceway Supported Enclosures, with Devices, Luminaires (Fixtures), or Lampholders. An enclosure that contains a device(s) or supports a luminaire(s) [fixture(s)], lampholder, or other equipment and is supported by entering raceways shall not exceed 1650 cm3 (100 in.3) in size. It shall have threaded entries or have hubs identified for the purpose. It shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs. Each conduit shall be secured within 450 mm (18 in.) of the enclosure.
If you want to stay with PVC you will have to support the box some other way.
And then of course the inspector could get you on exposed to physical damage as Redsy has pointed out.
Bob Badger Construction & Maintenance Electrician Massachusetts