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.
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.
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.
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.