Underground wire to outdoor recepticles

[Kilrduk]

I am looking to run an underground line from my "Stab-Lok" electrical pannel to the back of my yard. It will be used for landscape lighting as well as for running pond pumps and fixtures. I have a few questions regarding the proper way to do this:

1. What is the minimum depth that wire should be buried if not in PVC. Is there anything else that must be done to protect the wire (i.e. 2x4 over the wire etc). I would be using PVC to protect the wire coming out of the house and covering the wire until it is in the ground. As well, I would use PVC to protect the wire coming out of the ground at the back of the yard.

2. Do I have to use a GFI breaker if I use a GFI protected outlet? I have seen that GFI breakers are pricey - but I have not chekced out the exact price of one for my pannel.

3. What gauge/type of wire and breaker size is required? The run of the wire will likely be 80 feet, 60 of it will be underground. In the future I may add a few more outlets to the circut so I would want to make sure I plan for that in my choice.

[Mr Fixit eh]

1. The CEC requires non metallic sheathed cable to be buried at least 600 mm (24") below non-vehicular areas and 900 mm (36") below vehicular areas. An example of a vehicular area is a laneway, an example of a non-vehicular area is a lawn.

The Code permits these depths to be reduced by 150 mm (6") where mechanical protection is placed in the trench above the cable.

Direct buried cables shall also be surrounded by at least 75 mm (3") of 6 mm (1/4") nominal screened sand or earth.

A suitable electrical warning marker tape shall be buried along and above the cable route and be located approximately halfway between the cable and finished grade.

Where mechanical protection is used for reduced depth, it shall consist of one of the following and, when in flat form, shall be wide enough to extend at least 50 mm beyond the conductor, cables, or raceways on each side:

(a) Treated planking at least 38 mm thick; or

(b) Poured concrete at least 50 mm thick; or

(c) Concrete slabs at least 50 mm thick; or

(d) Concrete encasement at least 50 mm thick; or

(e) Other suitable material.

Ontario Electrical Safety Code Rule 12-012.


2. You can use either a GFCI receptacle or a GFCI breaker. If you have multiple receptacles, the GFCI receptacle can protect "downstream" devices.

3. If this is a general purpose lighting circuit you'll use 15A breaker with #14AWG cable. If there is a possiblity you might add a water fountain pump or two, you might want to go 20A with #12 cable. I'm not sure if the voltage drop is a concern with the length of your run. Wait for others to post.

Don't forget that you need cable rated for direct burial. Cable buried in the ground is considered to be in a wet location and the Code requires the use of either type NMWU (old type NMW) which is approved for wet underground installations. NMD90 type cable is approved for dry or damp locations only and is not approved for burial.

Steve