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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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  • Former Community Member
    0 Former Community Member
    John Peckham:

    Weardbeard


    When the PEN goes open circuit, and depending on the load on the network and the load balance on the network, current in the neutral will return to the transformer by any route it can. This includes bonded pipe work. These currents can be substantial and in some cases cause pipe work and conductors becoming red hot. Open PENs cause fires due to diverted neutrals and additionally over voltages damage and destroy connected equipment. 


    I have Ave an overhead PME supply to my house in Norfolk. That supply terminates in to the head at the front of the house. The copper water pipe enters my house at the rear of the house . Solid floor so the 10mm bond runs under the 200 year old floor boards. Without the insulated joint diverted neutral current under fault conditions could heat the bond up and set light to the wood.


    Have a look at the virtual IET ELEX show at the PME presentation video and you will see a couple of photos of examples of fire damage due to PME faults.

     


    Thanks for the reply! Just to get this straight- you have a 10mm main bonding conductor connected to your water service but have installed a plastic pipe fitting in the service to prevent the 10mm from setting fire to your floorboards?


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  • Former Community Member
    0 Former Community Member
    John Peckham:

    Weardbeard


    When the PEN goes open circuit, and depending on the load on the network and the load balance on the network, current in the neutral will return to the transformer by any route it can. This includes bonded pipe work. These currents can be substantial and in some cases cause pipe work and conductors becoming red hot. Open PENs cause fires due to diverted neutrals and additionally over voltages damage and destroy connected equipment. 


    I have Ave an overhead PME supply to my house in Norfolk. That supply terminates in to the head at the front of the house. The copper water pipe enters my house at the rear of the house . Solid floor so the 10mm bond runs under the 200 year old floor boards. Without the insulated joint diverted neutral current under fault conditions could heat the bond up and set light to the wood.


    Have a look at the virtual IET ELEX show at the PME presentation video and you will see a couple of photos of examples of fire damage due to PME faults.

     


    Thanks for the reply! Just to get this straight- you have a 10mm main bonding conductor connected to your water service but have installed a plastic pipe fitting in the service to prevent the 10mm from setting fire to your floorboards?


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