Discuss Please put my mind at rest in the UK Electrical Forum area at ElectriciansForums.net

Get the, cough, splutter, spark back to change the heating element for a less powerful one and have a warm tub instead! Saves on your leccy bill that way!!
Seriously though, it is a poor show that they fitted 2.5mm if they knew the rating of the hot tub first.
 
Firstly, I recall 2.5mm swa has a higher rating than 27 amps.

Has said spark been paid? Has he provided you with an electrical installation certificate? A commitment to notify under part P?
 
2.5mm thermosetting SWA has a current rating of around 36a clipped direct from memory...I don't have the BYB to hand. So a 32a OCPD device may be acceptable depending on installation method. The problem may be volt drop or 90 degree terminations, depending on the actual load being drawn, and manufacturers instruction. I think you are all jumping the gun somewhat stating this is wrong without all the info. BTW I've added a disagree to post #3 because it's misleading, there are instances where a 2.5mm conductor will be protected by a 32a OCPD. That said in practice I'd never use a 2.5mm based on the info given either. I don't think any of us would install a 2.5mm in this situation.
 
Last edited by a moderator:
The M.I should also contain details of a suitable OCPD,which if the cable size is 6mm,would be euro-ish. Most older units came with American wire sizing and protection device information.

There are some variables,and lee-way,in the OP's set-up,but would require more specification,and maybe assessment of current during use.....but it hasn't landed yet,has it....;)
 
I'd also add that it seems unlikely that the actual load will be over 30a given that the OP has indicated a 3kw heater, I cant see a filter pump adding that much, where's the rest coming from?
I agree, I can't remember the details but a while back I installed a piece of kit that had an operating rating of 2.7kw yet the manufacturers instructions "recommend" a 6mm supply cable. But it did say something along the lines of " This machine should be installed by a qualified electrician and in accordance with the wiring regulations"
Without all the relevant information its difficult to make a proper judgement call.
 
The MIs are there as a guide, how can they specify the csa of a supply cable when they have absolutely have no idea of the installation. I suspect they say 6mm because that's what would be needed if run in T&E in insulation. Suppose the hot tub was 200m away, would 6mm be acceptable then?
It's up to the electrician to design the installation.
 
Worked on quite a few tubs where the recommended supply was 6mm² and 32A the reality being with the heater and all pumps running they rarely run above 18 - 20A although the inrush starting the pumps does give a short current spike
 
Good points made by Wirepuller. I was blindly thinking of 2.5mm T&E max being approx 27A, but obviously different cable types have differing CCCs.
 

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