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Menace622 10-11-2010 07:06 PM

Outside Lighting
 
Hi I wanted to run some outside lighting, two lamp post and need to run wire underground. Can I just bury the wire or do I have to run it in conduit. If I can bury it want kind of wire do i need and if conduit what kinda to use. It would only be about 5 feet in two places. And any other information would be helpful. Like if i need to have GFCI protected. Thanks

rjniles 10-12-2010 12:47 AM

"Generally speaking 24" is minimum for UF cable (direct burial) and 18" for PVC with THWN wire. If the circuit is GFI protected before it goes underground, it is permissible to run the wire/cable at 12". For more details look up table 300.5 in the
National Electrical Code."

Also consider low voltage lighting where the requirements are much less strict.

Menace622 10-12-2010 04:39 PM

Ok thanks. My only question would be if i used low voltage would it be as bright? I want to install the big post lights not the small garden ones that you see in flower beds. Thanks

frenchelectrican 10-12-2010 08:56 PM

Quote:

Originally Posted by Menace622 (Post 515643)
Ok thanks. My only question would be if i used low voltage would it be as bright? I want to install the big post lights not the small garden ones that you see in flower beds. Thanks

With the low voltage luminaire not all are will be bright as line voltage will be and you will have to run a transfomer outside of the building and also run heveier conductor compared to line voltage will be.

Merci.
Marc

jddavis 10-12-2010 09:14 PM

Quote:

Originally Posted by rjniles (Post 515327)
"
If the circuit is GFI protected before it goes underground, it is permissible to run the wire/cable at 12".

18" minimum for PVC, does not matter if GFI protected or not. It does need to be btw.

rjniles 10-12-2010 10:37 PM

Quote:

Originally Posted by jddavis (Post 515887)
18" minimum for PVC, does not matter if GFI protected or not. It does need to be btw.

The NEC has an exemption for residential circuits that are GFCI protected and allows 12" burial depth

Table 300.5 (second vertical column from right) gives limited use of lesser
burial depth for the residential circuits described, as shown in Fig. 300-13. Any
GFCI-protected residential “branch circuit” not over 120 V and protected at 20 A
or less may be buried only 12 in. (300 mm) below grade, instead of, say, 24 in.
(600 mm), as required for Type UF cable for any nonresidential use or for a residential
“feeder.”
552 CHAPTER THREE 300.5
Fig. 300-13. This is OK only for a residential branch circuit rated not over
20 A and protected by a GFCI circuit breaker. (Sec. 300.5.)
Figure

jddavis 10-13-2010 02:50 AM

Quote:

Originally Posted by rjniles (Post 515937)
The NEC has an exemption for residential circuits that are GFCI protected and allows 12" burial depth

Table 300.5 (second vertical column from right) gives limited use of lesser
burial depth for the residential circuits described, as shown in Fig. 300-13. Any
GFCI-protected residential “branch circuit” not over 120 V and protected at 20 A
or less may be buried only 12 in. (300 mm) below grade, instead of, say, 24 in.
(600 mm), as required for Type UF cable for any nonresidential use or for a residential
“feeder.”
552 CHAPTER THREE 300.5
Fig. 300-13. This is OK only for a residential branch circuit rated not over
20 A and protected by a GFCI circuit breaker. (Sec. 300.5.)
Figure

Yea, i have to say that you are right, didn't know that :whistling2:. We always put PVC minimum 18", good practice to do because water lines dont go that deep where I live, and the electrical is the deepest pipe.


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