I am installing a water trough in a feed lot on a concrete walkway. It only has power for the heaters. There are no local codes. This is in the county. I have been looking in the NEC and had only found reference to this in a foot note. It reference’s to the American Society of Agricultural and Biological Engineers (ASABE) EP342.2-1995, Safety for Electrically Heated Livestock Waterers. I do not have a copy of this. I am told there is not any rebar or wire in the concrete. It is being fed with an 8/3 UF cable and the farthest one is about 800’ from the electrical panel. I was going to be driving a ground rod at the waterer but did not know if a GFCI device is needed on this. I will have some at 240 V and some at 120 V. The load is 4 - 250 W heaters.