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electric showers

Former Community Member
Former Community Member
Hello again, following on from the recent topic that discussed sizing electrical supplies to fixed equipment we have been asked to install 4 number 9KW electric showers into the same commercial premises as my earlier question on RCD protection to lighting.

Designer has asked for a 250A SPN sub board, (3 phase supply is available) and 4 x 60A SPN supplies to the showers with 60A DP isolators. When I checked the model MI they state a 40A supply is required. I queried this with the designer and his answer is that the showers draw 39A so wants the 60A supplies. Apart from the fact I can't find a decorative DP switch rated at 60A, am I missing something in that this feels unnecessary. No cable sizes have been discussed yet, 

Showers are on an office floor with 200 or so desks so assuming similar numbers of staff although not convinced that all staff will be lining up to use the showers on a daily basis. 

Again thanks in advance for any thoughts.
Parents
  • BusterK:


    If we're going with the 60A supplies it may lead to the circuit cable being oversized for the shower's terminals if we have to use 16mm instead of 10mm. I can't see omitting overload protection due to shower not being able to draw more than 39A being accepted so would need to size the cable for the OCPD. 

     


    So as a future proofing exercise putting in

    60A capable/sized supplies, but Protected at 40A

    60A cables to a local Isolator  (40A min)

    40A cabling from the local (to the shower) isolator to the shower ... 


    would mean that if the showers were ever up-graded,

    minimal re-work would be required to bring the whole circuit to 60A without going back to the board.
    (would a competent installer re-use underated cables - esp when they inspect the local isolator)

    PLUS

    the specifier gets the comfort of knowing they are not running their major portion of the cables to the max 'today'


    Doesn't that end up being win-win ?

    the installation can always have notes on why it was done that way (future proofing), if needed.


    or does that transgress some rule that you can't over specify a design (or clearly visible portions of it)

     


Reply
  • BusterK:


    If we're going with the 60A supplies it may lead to the circuit cable being oversized for the shower's terminals if we have to use 16mm instead of 10mm. I can't see omitting overload protection due to shower not being able to draw more than 39A being accepted so would need to size the cable for the OCPD. 

     


    So as a future proofing exercise putting in

    60A capable/sized supplies, but Protected at 40A

    60A cables to a local Isolator  (40A min)

    40A cabling from the local (to the shower) isolator to the shower ... 


    would mean that if the showers were ever up-graded,

    minimal re-work would be required to bring the whole circuit to 60A without going back to the board.
    (would a competent installer re-use underated cables - esp when they inspect the local isolator)

    PLUS

    the specifier gets the comfort of knowing they are not running their major portion of the cables to the max 'today'


    Doesn't that end up being win-win ?

    the installation can always have notes on why it was done that way (future proofing), if needed.


    or does that transgress some rule that you can't over specify a design (or clearly visible portions of it)

     


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