Installation for a HOT TUB?????

Andy Ellis · Jun 8, 2011

So I've taken the plunge and ordered a hot tub to be delivered on the first of july.

Right so I'm just designing the installation.

The tub will be located in my garden in a cabin that im currently building.

The tub is rated at 9kw, but I also want to power a pair of sockets and small lights. so tub max demand is 40A, small radial for 2 sockets 20A. small lighting circuit, 6A.

total demand 66A.

cable run not measured accuratly as yet, roughly 25mtrs, SWA will be clipped to outside of my house approx 12" above grounf level with cleats. when i have accurately measured run I will select appropiate size SWA cable.

Not within reach of the tub, but close by has to be an IP65 rotary isolator. This will feed a consumer unit in the cabin. prob 3 or 4 way. 1 for tub itself, 1 for power, 1 for lights. i was thinking an IP65 consumer unit due to potential steam from tub. please note the consumer unit again will be in the cabin, though as far away from the tub as poss. the cabin is approx 2 x 10mtr. only trouble with plastic cu is terminating the SAW? prob with metal cu is that it aint IP65? hmmm catch 22...

The main cu in house is 100A old with push button wylex mcb's. at capacity already, not in terms of demand, rather its only 6 way, so im thinking a new 1way 30mA rcd cu next to current cu to power the installation. just struggling best way here. how to feed new cu? meter tails ect? also i presume it would need to be metal to terminate SWA correctly.

truckster · Jun 9, 2011

You should be able to get an IP65 board that will accept an SWA but if you are going into a rotary isolator first which will take the SWA you could then take pvc to the board in trunking.

To feed it you could slit the tails in some neutral blocks, terminate the SWA into a metal switch fuse and either not rcd it or my preference would be a 100mA time delay RCD at the origin and a 30 mA RCD in the shed. As the shed could possibly be a bit earthy I wold TT that part of it. Don't forget to bond the water supply in the shed. A TT system would also mean you don't have to run a main bond back to the main house.

nickblake · Jun 9, 2011

ones i have done is run a 10mm SWA to a small CDU with main switch RCD in the shed from there to the 2 sockets and lights , then a rotay isolator for the hot tub and run from here to the hot tub in 6mm rubber 3 core flex , but this depends if the cable requires protecting
dont forget you leave the hot tubs on and do not switch them on and off ,in the main house if im honest i would upgrade the CDU too so you have an extra way for the hot tub and protect the circuit with a 50 amp mcb , im assuming the shed is wood so no need to TT ,

Engineer54 · Jun 9, 2011

Here we go again, ...TT everything in sight if it's outdoors!!!! No-one has stated anything here about the supply being PME yet either...lol!!!

No need for a rotary isolator before the CU, but you will need one for the Hot tub supply cable. Check the manufacturers data on there provided electrical panel, ....some include RCD protective devices!!

I would have a 100mA S type supply from house into the shed, then RCBOs in the CU where required for he sub-circuits....

Final word .....DON'T ''TT'' this installation..... lol!!!