Can anyone give a valid argument against running sprinkler wire in 1/2" pvc water line?

Question

1. Most sprinkler systems directly bury the wire next to the water line. So, this is a big upgrade from that. The main purpose is to protect the wire from being cut if someone digs there.

2. Why not use 1/2" pcv conduit? b/c it is double the price and the total distance I'm going to is ~600'. So, the cost is significant. PVC conduit is massively overkill as the wire is carrying low voltage and low current.

3. The voltage is 24 VAC and current is 350 mA. (.35A). The wires are switched by a computer for ~ 10 min on time duration per day. And the supply current will be limited by a 1/2 A fuse. The conductor ampacity is 13A.

The code is sort of ambiguous on sprinkler wiring. I am a Professional Engineer (Electrical), and my site is a rural ranch.

So, interested to hear any viewpoints.

Thanks in advance.

Edit:

In response the thoughtful answer about using some to mark to know where to dig, I place several inches of sand around all buried pipes. The soil here is a rocky, aggressively expansive clay and the sand allows ground shifts to avoid breaking the line as well as serving as a marker, so you know when you're close.

Answer 1

There are no code requirements that I know of regarding burying low voltage (IE sprinkler and LV outdoor lighting). PVC conduit is ridiculously expensive right now. Because there are no code requirements, you could protect it in any way you see fit. When I've installed sprinkler systems, I ran the valve control cables underneath the pipes going to the valves to protect the cable. But you could use PVC conduit (expensive), PVC water pipe, funny pipe (yes that's a real term) or just about anything.

It's a good idea to protect it, fixing a break is a PITA.

Answer 2

Cost and effort, like you said.

Done. Totally valid.

Answer 3

It's a good idea up to about 25 feet.

For 600 feet to save cost I would prioritize. Do it only where the wire is most exposed to damage: parts that are above ground, shallow, near flower beds or anything likely to be dug up by occupants, and a few feet either side of any termination, junction box, valve box, etc.

Elsewhere, if you're just crossing expanses of lawn, I'd bury the raw wire deep enough to avoid typical yard work eg aerators and dethatchers. If you want to be fancy you could add a 3 foot loop in a splice box every 50 feet to allow for easy diagnosis and repair of problems. That would be easier and cheaper than piping the entire 600 feet.

In addition to the cost/effort I'd experiment with the pulling capability of my wire before buying and laying all the pipe. If it's not designed for pulling it may snag and break with just so much as a single 45 degree bend. If you can't pull new wire through your COMPLETED BURIED conduit without breaking it .... it's a bad idea.

Answer 4

the trench is already there and shared with another 3/4" PVC electrical conduit containing 2 #8's

Clearly you can't put the LV in with the existing cables, but there's nothing stopping you from strapping the LV cable to the outside of the existing conduit.

There's certainly less protection this way, but more than having the LV cable direct-buried. A zip-tie every metre should be sufficient to stop them separating and drifting.