PE advice by Napit (hot tubs)

How does the 1 ohm that align with the NOTE in 702.410.3.4.3, which says 20 ohms, and only a "mat or electrode' - not a grid?

With difficulty ?

That is a very odd note. Its position seems to imply it only relates to zone 2 - even though ADS is permitted in zones 0 and 1 in some circumstances. 

In my defence, I'd point out it doesn't say 20 ohms, but “suitably low resistance” and gives an example of “20 Ohms or less". If the intention is to hold protective conductors at no more than (say) 50V above true Earth, then Ohm's Law suggests that the current flowing to the Electrode can't be more than 2.5A … for a domestic installation, let alone one that includes an electrically heated hot-tub - that doesn't seem to me to be “suitable”.

The suggestion that the electrode need only be connected to local supplementary bonding is also interesting from a diverted N currents point of view … with perhaps 1.0mm2 c.p.c.s being pressed into acting as main bonding conductors as it were.

   - Andy.

How does the 1 ohm that align with the NOTE in 702.410.3.4.3, which says 20 ohms, and only a "mat or electrode' - not a grid?

With difficulty ?

That is a very odd note. Its position seems to imply it only relates to zone 2 - even though ADS is permitted in zones 0 and 1 in some circumstances. 

In my defence, I'd point out it doesn't say 20 ohms, but “suitably low resistance” and gives an example of “20 Ohms or less". If the intention is to hold protective conductors at no more than (say) 50V above true Earth, then Ohm's Law suggests that the current flowing to the Electrode can't be more than 2.5A … for a domestic installation, let alone one that includes an electrically heated hot-tub - that doesn't seem to me to be “suitable”.

The suggestion that the electrode need only be connected to local supplementary bonding is also interesting from a diverted N currents point of view … with perhaps 1.0mm2 c.p.c.s being pressed into acting as main bonding conductors as it were.

   - Andy.