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I've never buried a cable before, or even run a conduit in a wall/floorspace, so this is all new to me.

I've dug half the trench across the garden so far. It's only 6" deep in some places as below that I found bedrock. 6" should be fine for this application, I think? But... a few metres of the trench goes under a gravel driveway though, and that's one of the spots where I've found bedrock. Still fine?

I've bought a cat7 SSTP direct bury cable (overkill, I know), but would like to further protect it with a pipe/conduit of some sort. Both from rodents and gravel but also from the compressive force of cars driving over it. Maybe I should lay the conduit in some sand before topping with gravel?

What should I be using, and how careful do I need to be about bends etc if I want to be able to re-run a new cable in the future?

My current plan is just to go to B&Q and see what general-purpose PVC piping they have, but I imagine there's better kit for the job...

Thank you!

edit: the underground run is only about 20m (no, I don't want to use wifi, I'd prefer a cable), and there is a mobile phone mast 200m away about 50m higher up the hillside. I think this probably means that I don't need to worry about lightning strikes too much. Would you still add protection at either end of the cable (it's just running from the main house router to an access point in the outhouse).

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The tower up the hill might take direct strikes before you, but those strikes might make big surges on the ground, so long story short, always use surge protection (or better, all dielectric fiber).

You don't necessarily have to meet the code requirements for electrical installations with your direct buried ethernet cable and I wouldn't worry too much about 6" of burial except under a gravel driveway. I don't think that will survive long. I don't think PVC will help much, I'd sleeve it in galvanized rigid metallic conduit across the driveway and hope for the best. (I am assuming this is just for home networking etc. and isn't anything life and death.)

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    I would not bother with the flexible nonmetallic conduit with a direct bury cable, I'd add the steel in areas where there's vehicular traffic etc., especially with gravel - I think gravel and cars / trucks will pulverize the cable like hamburger.
    – batsplatsterson
    Feb 20, 2020 at 10:41
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    I feel I need the full-length conduit so that I can run a new cable in the future if I decide I want to. Maybe I'll have cause for a second cable, or want to go up to cat8 (hah), or maybe my existing cable will need replacing post-lightning strike. Digging the trenches again would make me sad...
    – Codemonkey
    Feb 20, 2020 at 10:43
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    I think the flexible nonmetallic corrugated looking conduit is rated for embedment in concrete but not for direct burial, although it might be OK and again you have some latitude since this is not line voltage power. However if you buy the coils rather than the straight sticks it's not great to pull through. You have to keep the total bend under 360 degrees, i.e. four 90's, three 90s and two 45s, etc. Really getting another cable through later is always a crapshoot and iffy with 360 degrees, better chance if you can limit it to 270.
    – batsplatsterson
    Feb 20, 2020 at 10:50
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    Sched 40 PVC is pretty crushable, so vehicular traffic will definitely squish it flat. Sched 80 PVC is better but it's still plastic. At 6" depth you'd want rigid conduit (e.g. metal pipe, not even thinwall tubing).
    – Harper - Reinstate Monica
    Feb 20, 2020 at 12:07
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    All great ideas - Another idea is to have one or several pull strings running through the conduit. Run the string while you're putting the conduit run together in the ground. It's easiest to do this step while you can still access the conduit in case the string gets stuck. Then, when you want to run a wire in the future, use the string to pull the future cabling through the conduit. I would recommend using a thicker nylon string rather than the thin string the box store sells in the electrical department for this purpose - it's less likely to break when pulling. +1 on using rigid conduit.
    – technogeek1995
    Feb 20, 2020 at 14:15

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