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electric showers

Former Community Member over 4 years ago

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.

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0 Former Community Member over 4 years ago

All good points, this is an outline specification we have received and I know there is going to be an element of contractor design so was testing the water so to speak with the designer.

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. I have suggested using a 4 way 3 phase DB rather than single phase, that way we can connect the RCBOs 1L1, 2L2, 3L3 & then 4L1 giving plenty of room for heat dissipation if the showers are continually used. I don't know if the shower unit themselves would be capable of continuous use.

By decorative DP switch I meant a wall mounted flush unit rather like 1 used for a cooker (with no 13A socket) rather than having to fit a rotary isolator, I know MK used to do a 50A version so that on a 40A supply would seem to be more suitable to me, just was wondering if I had missed something on their response of current draw is 39A so install 60A supply.
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0 Former Community Member over 4 years ago

All good points, this is an outline specification we have received and I know there is going to be an element of contractor design so was testing the water so to speak with the designer.

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. I have suggested using a 4 way 3 phase DB rather than single phase, that way we can connect the RCBOs 1L1, 2L2, 3L3 & then 4L1 giving plenty of room for heat dissipation if the showers are continually used. I don't know if the shower unit themselves would be capable of continuous use.

By decorative DP switch I meant a wall mounted flush unit rather like 1 used for a cooker (with no 13A socket) rather than having to fit a rotary isolator, I know MK used to do a 50A version so that on a 40A supply would seem to be more suitable to me, just was wondering if I had missed something on their response of current draw is 39A so install 60A supply.
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electric showers

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