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PE advice by Napit (hot tubs)

ebee

There is an article in PE and I have just received it via email.

I am disappointed that the article seems to suggest that it contains all you need to know yet no mention is made of earthing systems

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    AJJewsbury: 
     

    where the fault current exceeds the residual operating current, the touch voltage may also exceed 50 V until the device trips.

    But the touch voltage won't persist - as the RCD will trip. 

    My point being, that the RCD trip is based on dry conditions … may be suitable for wet, but NOT submerged (so, consider steps metal into pool or sauna, and fault in heater element.

    Remember I was comparing the situation with the problem of perceived shocks on PME systems - due to voltage drop along PEN conductor in normal, non-fault, conditions.

    We say to avoid PME partly because perceived electric shocks from the PEN conductor which can potentially be up to (say) 18.4V above Earth, yet we recommend a TT system - possibly TT'd an entire installation - where there's no guarantee that voltages of anything up to to 50V might persist. 

      - Andy.

     

    The PME diverted neutral currents may persist indefinitely … and local RoEP in an open-PEN situation may persist for a very long time (although it probably varies within that period).

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  • 0

    AJJewsbury: 
     

    where the fault current exceeds the residual operating current, the touch voltage may also exceed 50 V until the device trips.

    But the touch voltage won't persist - as the RCD will trip. 

    My point being, that the RCD trip is based on dry conditions … may be suitable for wet, but NOT submerged (so, consider steps metal into pool or sauna, and fault in heater element.

    Remember I was comparing the situation with the problem of perceived shocks on PME systems - due to voltage drop along PEN conductor in normal, non-fault, conditions.

    We say to avoid PME partly because perceived electric shocks from the PEN conductor which can potentially be up to (say) 18.4V above Earth, yet we recommend a TT system - possibly TT'd an entire installation - where there's no guarantee that voltages of anything up to to 50V might persist. 

      - Andy.

     

    The PME diverted neutral currents may persist indefinitely … and local RoEP in an open-PEN situation may persist for a very long time (although it probably varies within that period).

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