Seems like I'm on a "roll" here for post. This job I'm on is bringing up a lot of questions. I always hear that the ditch for UF cable is 18", but from what I see in Table 300.5, unless it's under one of the special conditions in the table ( concrete etc.), it is 24". Everybody I've ever heard just about, says it's 18". A customer just told me one of the DIY books said 18". Am I missing something here. I've heard this all my years in electrical work, but as I read the code, regular underground depth is 24". Thanks again.
24 unless you can meet one of the other conditions.
Most notably is 12" for a single 120v, 15-20a GFCI circuit at a residence.
18" is RNC (PVC) conduit, a better choice for a lot of reasons.
Where I am in Canada, its 18 inches if protected (wood covering or poly pipe) and 2 feet if not.
This is for non vehicle areas where it has to be deeper.
Yes sir, treated (non creosote)lumber 2x4 or 2x6
see page 13 & 14 of the h/o brochure from our city.
http://winnipeg.ca/ppd/pdf_files/HOElec.pdf
That must be a Canadian thing. The typical .40 or .25 CCA or ACQ "treated" lumber would be stringy dust here in less than 10 years underground.
In 1969 my folks built a new garage and after it was inspected and passed, they decided to put power into it for a few outlets and lights.
I can vividly remember my mother tossing the painted 1x6 boards from when they took the fence down into the trench to protect the cables. I inherited the house so one day I should dig down and see how much of the "protection" is still intact.
Most dyi's use the plastic pipe as protection as its easier to buy it at the big box and put a roll in the back of their car.