I'm planning to run 300 ft of direct burial, 12 gauge, 3-conductors, no ground cable. Buried underground. The cable will carry 240v split phase.
The main panel at the start of the run is already grounded.
Do I absolutely need to have a grounding wire INSIDE the cable?
Or can I just properly ground the sub-panel at the end of the run?? (grounding rod, grounding wire to the ground post of the sub-panel)
EDIT: the loads will be a few lights, a 12v battery charger and 2 electric space heaters, so all resistive loads…believe it or not there's already a "ghetto" 200 ft run of 14/2 indoor romex wire going there (from previous owners) but the lights and battery charger work fine even with the massive voltage drop..
EDIT2: yes this is mostly a cost consideration, however after a bit more research I will use a cable with a grounding wire inside (didnt buy the cable yet)
Thanks everyone
Best Answer
The National Electrical Code, that is the controlling document is most locations of the US, requires a 4 wire connection between a main and sub panel now.
That is; the two hot legs, the neutral, and a grounding wire. The ground wire can be a separate wire from the other wires but should be run in the same trench with them.
You still have to establish a ground at the separate building using one of the Code approved methods for a grounding electrode. Such as the one you cite in your question.
There are many questions here on SE that address this issue.
Good luck!