John Ford said:

Hot tub supplier says they regs will change soon to require TT on hot tubs

I find that a very interesting statement.

Reasons NOT to install a hot tub.

1.Earthing problems.

2. High cost of heating unless you use solar panels and no electricity.

3. Dangerous water with chemicals added and germs.

4. Unwelcome friends and neighbours want to come and use it free and don't even bring a bottle of something or snacks.

5. Expensive to buy.

6. Bad for the health in the winter.

7. Removing broken wine glass shards at bottom of hot tub after party is no fun.

8. Vomit floats on surface of water. Most off-putting.

9. Weight gain.

10. High maintenance.......

Tips For Having a Great Hot Tub Experience - Bing video

Z.

A sobering tale written in foreign just to make it more dramatic...

Short story: A hot tub disaster | HeraldScotland

Z

All plastic piping from hot tub to heat pump, no connection between hot tub and house plumbing or outside tap.

But any metallic connection between the heat pump and anything inside the house still on the PME earth? Pipework, or c.p.c.s in control wiring between inside and outside units? If control wiring is ELV between inside and outside, are any of the ELV conductors earth referenced or reliant on a reasonably consistent earth potential for EMC reasons?

   - Andy.

Hi Andy, hot tub supplier has requested electrical feed to heat pump on separate house circuit through fused connection unit with th earth line connected through to heat pump. So the hot tub is most certainly has a metallic connection on PME earth. There will be electrical connection between heat pump, PME, and potentially (if we follow hot tub suppliers requirement) and the hot tub (TT).

So the hot tub is most certainly has a metallic connection on PME earth.

So the whole purpose of TT'ing the hot tub is entirely defeated?

   - Andy.

electrical - Why am I getting an electric shock from the water in my hot tub? - Home Improvement Stack Exchange

Z.

To be honest Andy as a mechanical guy I am not sure. I assume the PME earthing will end at the heat pump and the earth on the hot tub is connected to the earth rod. Therefore there is no direct earth connection between the hot tub and the heat pump. The issue raised in previous posts was the location of heat pump being within 2 metres of hot tub and on different earthing systems. 

The plot thickens and I am even more confused than before so if any of the experts on this forum could help it would be appreciated.

It appears that the electrician's position is that the only way to make the hot tub installation compliant is to make the complete house installation TT which seems a drastic step. What I have taken from this forum so far is that as long as there is appropriate separation, 2 metres minimum, between equipment, sockets, lights, heat pump that are PME from the TT hot tub that is compliant with regulations. The other sugestion that came up was to put a physical barrier between the TT hot tub and the PME heat pump which is also practical. Have I got this wrong? Is the only way to be compliant to TT the whole house or is physical / distance separation compliant with a resonable / practical interpretation of the regs?

If you TT the whole house then it is wise to use double pole R.C.B.Os for EACH circuit. You don't want just one R.C.D. tripping off and disconnecting everything.

If you just TT the hot tub the earhing rod needs to be well away from any P.M.E. earthed stuff. Out of the resistance area of any P.M.E. earthed equipment.

Personally I prefer TT earthing for hot tubs, with at least two R.C.D.s wired in series to provide belt and braces protection in case one R.C.D. fails or seizes up when it is needed.

Z.