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HOT TUBS ANY VIEWS OR ISSUES?

John Peckham
I have been chatting to a mate of mine who is a very experienced sparks who does 10-15 hot tub installs a year. He TTs his supplies to hot tubs which are on PME supplies which is the majority of supplies in Essex other than the odd TT supply in country areas.


He does get called back to hot tubs that he has not carried out electrical installations because people climbing in and out of the hot tub where people have experienced "tingles" ie minor electric shocks. Sure enough these shocks are due to the hot tub being directly connected to the PME earth.


Currently (excuse the pun) BS 7671 701 and 702 do not cover hot tubs only the general rules in Parts 1-6.


Does anyone on the forum carry out hot tub installations and if so how do you do it? Has anyone been called to investigate "tingles"? Does anyone know of any more serious shocks or injuries relating to hot tubs or any other equipment connected to a a PME supply?


Thanks in anticipation.


JP


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    It’s hard to imagine what part of the hot tub people are touching to get tingles, unless they are doing maintenance whilst wet and virtually naked, something I am very cautious about doing.


    I TT hot tubs, but surrounding lights can be an issue, those nice stainless steel bollards in particular.
  • 0
    Are pumps and heaters all class 2 then ? If not then I'd expect the water to be close to CPC voltage, once a bit of sweat or whatever makes it a more conductive.

    Mike
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    As I understand it apart from some of the ones that plug in on a 13A plug top they are all Class 1 requiring an earth connection. The heaters and pumps are Class 1.


    Mike


    Yes that is the problem the metallic parts connected to the CPC are in contact with the water which is at the potential of the supply neutral. The supply neutral voltage will vary depending on the load on the network and load balance. The problem of "tingles" arises when in contact with the water and simultaneous contact with the general mass of earth. Add to the issue with immersion in water of substantial part of the body and you may be getting in to the dangerous areas of the IEC time current shock curves.
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    I can see the risk. I guess one solution is not to get in while it is full of water.. and another  is not to step out directly onto the ground but rather via something that adds a few k ohms in series, like decking, plastic steps or even to abseil in and be winched out using a synthetic rope. Maybe not the last ones.


    However,  having said that, unless we can persuade folk to bathe in transformer oil, like the car charger, a local TT island that connects the exposed potentials to  whatever the surface potential is nearby seems to be the obvious electrical fix. As a non hot tub user, who does quite  bit with earth electrodes,  I think your mate is doing the sensible thing. It may be tricky if other items at house earth potential are in reach such as outside taps.

    M.
  • 0
    John Peckham:

    I have been chatting to a mate of mine who is a very experienced sparks who does 10-15 hot tub installs a year. He TTs his supplies to hot tubs which are on PME supplies which is the majority of supplies in Essex other than the odd TT supply in country areas.


    He does get called back to hot tubs that he has not carried out electrical installations because people climbing in and out of the hot tub where people have experienced "tingles" ie minor electric shocks. Sure enough these shocks are due to the hot tub being directly connected to the PME earth.


    Currently (excuse the pun) BS 7671 701 and 702 do not cover hot tubs only the general rules in Parts 1-6.


    Does anyone on the forum carry out hot tub installations and if so how do you do it? Has anyone been called to investigate "tingles"? Does anyone know of any more serious shocks or injuries relating to hot tubs or any other equipment connected to a a PME supply?


    Thanks in anticipation.


    JP


     


    Yes John I have installed hot tubs and always TT earth them, preferably through two series connected R.C.B.s. I have had no reports of tingles.


    Z.


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    Zoom


    Good man. 


    Just make sure your TT electrode is at least 2-3m away from any underground metallic pipe work connected to the PME earth. Also make sure any exposed or extraneous conductive parts connected to another earthing system are not simultaneously accessible to your TT system.


    Should not be too difficult to keep the TT earth away from underground pipe work as the tub tends to be in the back garden and the supply pipes in the front garden.
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    Should not be too difficult to keep the TT earth away from underground pipe work as the tub tends to be in the back garden and the supply pipes in the front garden.


    Yes indeed John. We need Superman's X-Ray vision to help locate underground metalwork.


    Z.


  • 0
    Zoom


    I the absence of any super powers a Cat and Genny would have to do.
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    mapj1:

    It may be tricky if other items at house earth potential are in reach such as outside taps.


    How else would one fill the tub?


    Time for an insulating segment in the tap supply!


  • Former Community Member
    0 Former Community Member
    Views or issues as per heading!


    I always get the installer to fit a kWh meter for the hot tub supply as it saves arguments about the eventual electric bill coming in far higher than the salesman's indications that the running cost is "less than a cup of coffee a day" (sic).......... The cost of the chemicals and testing kits doesn't get much of a mention either!


    Although one good idea I did see was on arrival, the guys drag in a very large "bladder" and connect to the outside tap so that when they've finished assembling the tub etc, they can simply drop in a submersible pump and rapidly fill the tub rather than hang around for hours waiting for the hosepipe to fill when assembled.


    Regards


    BOD

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