I want to run a cable to an outside post lamp I am installing. But, I would rather NOT bury the cable deep.
I want to put it inside a conduit and bury it only about 3 inches. Is this legal? Any potential problems with this, as far as snow/frost?
Also, I want to connect it to an current porch light (will just run from wires inside porch light). Plan to run wires down to ground from porch light, under the wooden porch, and then into 3″ buried conduit to the post lamp.
Thx for any advice.
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6 Responses to “Buried cable to outside post lamp – must I?”
National Electric Code requires type UF (underground) cable to be buried to a minimum of 12", conduit to a minimum of 18" (that’s not a typo, I don’t understand why conduit needs to be deeper). In many areas, that is not below frost line. Where I live, frost line is 48". I definitely would not use a depth of 3" to run this line. Use the correct cable, and use 12" as your minimum. Hope this helps.
as long as the wires are not exposed you can do it. but make sure the wires do not come exposed.i think you should bury them deeper then 3 inches also.
Generally you would bury the cables to at least 18" below grade. Any less than that usually does not meet code , and has the potential of someone inadvertently putting a shovel thru it if they are not aware of the buried cable. You also do not need to use 3" conduit for a 14/2 wire. 3/4" would do and you really should use wire designed for underground or ‘wet’ locations. NMW , not NMD rating
I would go down at least 15+ inches to be safe from shovels/edger’s,
still in the conduit you should leave something in the meter box showing where the cable runs from/to and the depth
All of the other instructions are correct – for normal household 120V lights it should be 12-18 inches below ground (plus be sure to use a Ground Fault Interrupter (GFI) somewhere so if there is a problem it will be safe).
A buried power line can be closer to the surface if it is not in a conduit because it is flexable.. so frost heaves will not affect it as much as rigid conduit.
However, if you really want to go only 3 inches.. get a low voltage (12V) light for the post lamp, a voltage converter at the house and you can run the power line at 3 inches.
If the circuit in question is limited to 120 volts, and you use pipe to run the cable/wires in, you only need to bury it 6" deep. If you use direct-burial cable you need to be 12" deep.
Have an electrician run a wire from the switch, to an outdoor box with a GFI outlet.
From this dig out to where you want to put the post. Have him install 3/4" PVC pipe out to the post hole, (vs. 1/2"-it’s MUCH easier to pull the cable into it). Snake in the cable, and be careful not to damage the cable with the post. There should be a hole in the side of the post about 18" up from the bottom, for the wire to enter. Make sure you don’t bury the end where the cross-bar goes through (learned that one the hard way!!)