I know this is a long winded but it is a must to understand the reasons why we are required to install equal potential bonding around a pool, this as well as stray voltages are so mis-understood as well as what a ground rod can or can-not really do to prevent a shock hazard, I have seen even well seasoned electrical engineers who don't have a clue about these two subjects, along with inspectors alike, to not understand these two subjects Can set yourselves up to some large liabilities as well a even criminal charges if someone were to get hurt or killed from not following the correct way to make a pool safe, yes there has been quite a few electricians charged with a crime, in some cases even involuntary man slaughter in cases where they did not not follow safety protocall and or the NEC, I think every electrician should know these subjects forward and backwards before they ever work on or around a pool or other similar electrical installations.
It is simply like this: Did you know that you could have a properly grounded (EGC) and protected (breaker/GFCI) load by a pool and a person immersed in water of the pool could still receive a shock large (2 volts or higher) enough to kill them and never trip the GFCI or breaker, and or even if it was tripped, they would still be shocked? if not then you must read on.
The above is why we also must include an equal potential bonding (EPB) system around all bodies of water where a person might likely be immersed in water and can contact earth or something at the potential of earth such as the concrete shell of the pool or the pad/deck around the pool that also has metal items electrical or not that might be at the potential of the service grounding.
First the idea is not to provide a path back to the grounding system for the service, this is not the function of EPB, the idea is to form a connected plane where everything is at the same potential so even if there is such an event such as a lost service neutral or even a bad service neutral that can cause everything that is connected to this service neutral via the main bonding jumper to rise to a voltage potential above the earth reference of 0 volts to be kept at this same voltage rise so there is not a difference of potential.
The reason a bird can sit on a wire that may be several thousand volts above earth potential is that every thing this bird can touch is at the same potential, well maybe a large bird such as an eagle might be able to touch another phase but the idea is the same.
Let's say the voltage drop of the service neutral is about 3 volts from the utility transformer and the service, since all the buildings grounding will also have this same voltage rise from remote earth and any grounding connected to this neutral, this includes this chair lift if it has an electric motor that has an EGC running back to the service, same goes for anything electrical around this pool, if the concrete pad around the pool or even the earth if there is no pad, will have this voltage difference between it and this pad unless the two are bonded together, this also goes for the concrete shell of the pool, or anything else that may be at the potential of the earth as they are in contact with the earth, a ground rod or even a CEE will not have a low enough impedance to earth to remove this voltage or even lower it enough to make it safe, 3 volts might not seem like a lot, but 3 volts across a persons body that is immersed in water can disable that persons mussels enough to make it impossible for them to pull themselves out of the water, or even keep their head above water, it does not take much voltage on a person immersed in water to cause a drowning.
By bonding all these areas together brings them all to the same voltage potential (3v) so even though they have a voltage above earth there is no voltage difference between them so no current can flow across a persons body, but this can only work if you can access the re-bar in the concrete for both the pool and pad/deck to connect to, and or any other metal or concrete that may be in around this pool, this #8 AWG wire has a low enough impedance to remove a difference of potential, a ground rod or other types of electrodes do not have this ability simple ohms law will show this.
but unlike poplar belief, stray voltages do not travel through earth and raise the potential of earth, its always the other way around, it is the conductors we supply or other conductive pathways that are connected to the service grounding that is also connected to the service neutral that brings in the stray voltage, as said it can be a voltage drop on the service neutral, or it can be a voltage drop on the primary neutral because it is also bonded over to the secondary neutral, that may be a mile down the road that has a bad connection and has a voltage rise above earth.
Another way to explain this about ground rods or other types of electrodes can be done like this, ask the person who thinks a ground rod can remove this voltage this question, if you used a ground rod as the neutral return path for a load, via connecting the supply hot to one side of the load then just connect the neutral side of the load to a rod, and this load exceeds 4.8 amps, the rod is at 25 ohms, what would be the voltage on this rod to remote earth, lets just say 3' away from the rod, the math is simple, lets say you have a load of 10 amps, 10 amps x 25 ohms is 250 volts that would drop across this rod, this means that the full 120 volts would drop across the rod, at the 3' shell around the rod you would drop 75% of this voltage which is 90 volts, so a person knelling at 3' feet away from this rod would receive a 90 volt shock if they were to touch this rod, now lets even lower the load to just 2 amps, 2 x 10 is 20 volts, 90% of 20 volts is 18 volts, so even at 2 amps this rod can not lower the voltage enough to protect a person immersed in water, now think about how much current on the service neutral that it would have to be that could cause a 3 volt drop across the neutral, 40, 50 amps?? do you think that this little ground rod can have an effect on that 3 volts? I hope you would think not.
Remember this at 25' away from this rod you will drop the total voltage that is on this rod, that means if this rod is placed 25' away from where a person could contact this chair and earth or the concrete pad or pool shell that is at the potential of earth, and there was 120 volts on the chair you would have a voltage of 120 volts to any earth reference point, so this is why we are to try to bond everything together so even if this happens that everything you can touch is at this same 120 volts potential and there would be 0 volts between these parts and no current can flow through a persons body, and there would be no shock potential, again just like a bird sitting up there on that primary wire at 7200 volts, and he never feels anything.
So this is the reason there is no need to try to run the EPB conductor back to the panel, it would serve no purpose and not make anything any more safe, the EGC that is run with the branch circuit from the service to any load by the pool is all that is needed to cause the breaker and or the GFCI to trip if a fault was to occur in the load, the only way to over come what some call stray voltage such as the bad or under sized neutral problem is to install a EPB conductor to all accessible electrically conductive parts around the pool that a person could come into contact with while immersed in water, and being that this chair lowers a person into the water, it would be extremely important that the chair concrete pad/deck and pool shell are all bonded together so that there is no possible way a person to touch between two points that would have a voltage difference.
I know some will say that this is an existing install and it can remain as is, even if your inspector also agrees with this, to me the liability side of it, will make me do it the safe way just because I would not want to ever live with the thought I had a chance to make something safe but didn't and a child was killed or anyone for that matter, this is what rules the way I approach jobs like this, yes it has been there for years, but it only takes loosing the service neutral one time while a swimmer is in the water to cause the hazard the EPB system is needed, so this is not an IF, it is a when will it happen?