Electricians..... Code question.

[John Pollman]

Hi all,

Do we have any licensed electricians here? I don't have a current code book and I want to do some outdoor lighting and I just want to check and see if what I want to do is kosher. Here's what I have and what I want to do.

I've currently got a dedicated 15A GFI circuit that I was running my low voltage landscape lighting with. I'm sick of replacing bulbs and correcting bad connections from the cheap cheesy connections that they use on the low voltage fixtures. Last week while cleaning out the beds in front of the house I ripped out all of the old JUNK low voltage stuff. I've found some nice 110V outdoor spots that I just want to light the front of the house with. They are designed for "landscape lighting". I already have the circuit there and just want to tie into it and run 14/2 wire designed for direct burial. I don't want to go down 18" or more so I'm planning on just putting it in the gray PVC conduit. I just want to run the wire in the conduit and into the junction boxes at each fixture. There is only five fixtures total. I want to use the PVC junction boxes and install one of those watertight covers on them. The covers have a gasket and a threaded hole that the fixture will mount directly to. I just want to set the boxes flush with the ground level.

Will this setup meet current code ? I thought that as long as the wire was run in conduit it can be shallow.

I just don't want to get into this and find that I need to do $500 worth of electrical work.

Thanks

John
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[Rob Russell]

John,

I'm not a licensed electrician, but I do have the 2005 NEC and like to think that I can read it.

Article 300 is Wiring Methods, 300.5 is Underground Installations, and Table 300.5 specifies the Minimum Cover Requirements. This table has 5 columns that list various applications, one of which is "Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes". I'd say that pretty well describes your application. For direct burial-rated cable, the minimum cover will be 12". If you want to run "Rigid Metal Conduit or Intermediate Metal Conduit", the minimum cover will be 6". Sorry, but "Nonmetallic Raceways Listed for Direct Burial Without Concrete Encasement Conduit", have a minimum cover of 18". There is a note that effectively says the nonmetallic raceway can use the shallower depth of the Column 4 application. You can run the plastic conduit or direct burial shallow (6") if it's under 2" of concrete.

To summarize the above, given the circuit you are running, these are your options:

6" Minimum Cover

Rigid or Intermediate Metal Conduit
Nonmetallic Conduit listed for direct burial with 2" concrete over it
Direct burial cable with 2" concrete over it12" Minimum Cover

Direct burial-rated cable
Nonmetallic raceways listed for direct burial (and pull individual conductors like THWN)Note that you can't use normal NM anywhere here, even in conduit, because it's not "wet location" rated. Note also that plastic conduit must be listed for burial, you can't just use any plastic conduit - make sure it's rated for underground applications.

There is another code requirement that you should be aware of. If you use direct burial cable, the vertical part of your installation must be "protected from damage" (sleeved) from the minimum cover depth up.

While it's not a requirement, I'd put a warning tape 6" above your cable or conduit if you go plastic. That way it's really clear to someone 20 years from now who's digging that there is an electrical installation underneath. You know where the circuit is run now but someone else in the future may not. It's never safe to assume when digging where there are wires.

Good luck with your project and hope this information helps.

Rob

[John Pollman]

Thank you very much Rob ! That's exactly what I was looking for. The ridgid PVC that I was planning on using is rated for direct burial. Actually, digging isn't that big of a problem because it's in a planting bed and I can get down to 12" easily. I think I'll just do that and use metal conduit and run individual conductors of THWN. I'll just put a riser on the box and mount the fixture to that. I've already got a timer on the circuit and it works well for landscape lighting use. I think I may even install a photocell to override the timer if it's not dark out. (This helps so that I'm not always having to keep changing the timer settings as the days get longer and shorter ;)) I'm amazed at what just a little lighting on a house at night can do for "curb appeal". It looked great with the system I had but those CHEAP connections they use on the LV systems are just a joke. And the bulb are expensive so I'm just going to bite the bullet and go with a line voltage system and be done with it.

Again, thank you very much for your research. I just want to be sure that I'm doing it correctly and SAFELY.l

Take care,

John

[tod evans]

john, i read what rob posted as "no-plastic" please reread..02 tod

[John Pollman]

Yeah Todd, I was up late last night and haven't been up very long. I meant to specify metal and typed PVC..... I made the edit. ;)

Thanks

John

[Bill Lewis]

John, if you are using metal conduit, be aware that there are three types of metal conduit. I don't think this stuff that HD sells is not the right stuff for direct burial. Ridgid is pretty much the equvalent to pipe but can't be bent very easy, if at all. The intermediate is pretty heavy, but can still be bent. The light stuff that HD sells can be bent pretty easy with a conduit bender.

Electricians? correct me if I'm wrong about this.

[John Pollman]

I think you may be right Bill.

I've got a pretty good electrical supply house about five minutes from me so I may just get the supplies there and just the fixtures at HD. I've got a conduit bender though so that's not a problem.

Thanks !

John

[Rob Russell]

john, i read what rob posted as "no-plastic" please reread..02 tod

Tod,

PVC conduit is fine for an underground application, provided it's listed for use in an underground application.

Rob

[Steve Ash]

John, Rob knows his stuff for sure.....I still have a strong aftertaste from eating crow. :D