hot tub

17 Mar 2005
Reaction score
United Kingdom
some advice please
i am having a hot tub installed and it needs a 30a supply
i have a 4mm armored cable running to my shed on rcd
can this be used to connect to
on the wholesalers website it says that it will carry 42a ??
or should i put in a new cable
any advice please
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i have pasted this from the hot tub website,

Electrical Supply
The Catalina range of spas is the best performer on the market and needs appropriate power. For this reason, depending on the model chosen, the power supply will be either 20 amp or 30 amp single phase.

This must be wired through an R.C.D (or circuit breaker) at least 2 meters away from the hot tub. Any buried or exposed cable must be armoured and should terminate beside the site of the hot tub with a 4m tail. We strongly recommend a waterproof isolator switch positioned within a few meters of your hot tub.

the heater in mine will be 3kw
so what size cable will i need please
and what will the tail be (flex) ? or some swa ?
any help please
is there anyone out there with an answer please,
FYI, 3kw is only 13A, not 30.

What setup do you have in the shed? and how far away will the hot tub be?
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thanks for the reply
the heater in the tub is 3kw
but the dealer says i need a 30a supply
it also has two pumps and filter etc,
it will be only 1m from the shed,
i have a 4mm 3 core swa to the shed at around 20m
fed from a 32a mcb with a time delay rcd in the unit
i also have a 30ma rcd on the shed end at the moment
directly connected to some twin sockets
so i did intend to fit a isolator for the tub
but will my swa be suitable
and what to use to go between the isolator and tub
many thanks
That all sounds fine. Run a length of 4mm² SWA from inside the hot tub, if possible, to a 20A MCB in the shed Consumer Unit, if there's space. Then either ON or NEAR the hot tub, you need a 20 DP isolator.
one of these:

Are you aware of Part P?

Perhaps the dealer was confused with the other model he has available, the one which requires a 30A supply ;)
thanks for the info
i have had a look at the info on the hot tub
and the one i intend to get defiantly needs a 30a supply
it also has two big pumps in it as well as the heater
and it must have another pump for the filter
so is the cable size still ok and should i use a 30a dp switch
thanks again
(yes i am aware of part p.)
the dealer will do the connection just need to make sure the shed power will handle it.

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