PE advice by Napit (hot tubs)

mapj1: 
 

If one ohm is reasonable  rather depends on the other impedances in the rest of the PME system fed from the same substation. 20 ohms may be a book figure, but to expect that to do much equalization against all but the weediest PME supply is optimistic in the extreme.

I agree … but I think the trick is that G12/4 is talking about a grid under the “poolside areas” here, to control step potential, rather than controlling a touch voltage. In that case, the actual resistance to earth matters less … I'm guessing the 20 ohm figure in the note in Section 702 dropped out of what's considered reasonable for PME as an “end of line” electrode in line with current industry practices …

mapj1: 
 

If one ohm is reasonable  rather depends on the other impedances in the rest of the PME system fed from the same substation. 20 ohms may be a book figure, but to expect that to do much equalization against all but the weediest PME supply is optimistic in the extreme.

I agree … but I think the trick is that G12/4 is talking about a grid under the “poolside areas” here, to control step potential, rather than controlling a touch voltage. In that case, the actual resistance to earth matters less … I'm guessing the 20 ohm figure in the note in Section 702 dropped out of what's considered reasonable for PME as an “end of line” electrode in line with current industry practices …