Pre-work advice needed.

[alien2]

I'm considering having a hot tub in my garden and i'm trying to cost it out roughly before I jump in(!). I already have a wired garage half-way down the garden, 15m away. Its wired for lights and power with its own CU, 6A MCB & 20A MCB. In the house next to the CU is an ELCB for the garage power. All this was here when we bought the house.

I'm now considering a hot tub in a summer house at the bottom of the garden, another 10m down down the garden. Hot tub plugs straight into a plug top, I would also need a light in there and power for a radio or something.

Do I need a complete new cable from the house or can the Summerhouse be spurred from the garage?

Thank in advance for any advice.

A2

 

[Spark123]

What size fuse and what size cable feeds the garage CU? How long is this cable and how is it run in? Is the ELCB a current operated type i.e. has 2 Live and 2 Neutral wires going to it?

 

[alien2]

OK, a bit more investigation reveals the following:-

Cable in the house is 4mm twin core + E.
RCD 80A rated 300mA trip has Live & Neutral going in, live & neutral coming out and the out cable has the earth going back into the CU.
Looks like its fed by a 20A wire fuse as there's only two 30A's, one 5A and one 20A in there.

Cable out of the house is SWA buried under the patio & ground to the garage 15m away. Garage is 5m long and the summerhouse would be about 3m further away.

Hot tub plugs into 'standard 13A socket'. One I'm looking at has a 2Hp (1.5Kw??) motor, no heating element as the heat is recovered from the motor. Others have a blower and up to a 1.5kw element.

What do you think? Garage has 2 off 4 foot fl. tubes, 1 standard size freezer I only ever run the lawnmower in addition.

What do you think?

Cheers

A2

 

[alien2]

Searching this great forum has given me some tips. I've found out the tub I'm looking at only uses 6 amps max, so the 4mm TC&E running from the house to the garage will be OK.

Here what I'm thinking:-
Replace the two way CU in the garage with a 3 way and a 10A MCB.
Run some 2.5mm TC&E from the new CU to the back of the garage (5m).
Junction box and connect to SWA, bury and run to the new summerhouse (3m).
Use the old garage 2 way CU to connect a fused switch for the tub and the other for power.
Leave the existing RCD in the house for protection.

Sound OK??

A2

 

[kendor]

Searching this great forum has given me some tips. I've found out the tub I'm looking at only uses 6 amps max, so the 4mm TC&E

only 6A? how long does it take to warm the water up! or is it a hot fill?

 

[ebee]

RCD 300mA ? or 30mA

 

[alien2]

The RCD is definitely 300mA. Very odd, why would someone fit a 300mA one? That will need changing to 30mA then.

The other strange thing about this installation is that there is a very standard looking light switch marked 'garage power' at the back of the house that can be used to isolate the power. I think the bloke who put this lot in had a ten gallon hat and stirrups. This will need some investigation and a suitable replacement.

And yes, some small tubs recover the heat from the running motor for the water so need no heater. They take two days to warm up rather than one but the theory is you save some running costs as a result. All the one's I'm looking at are less than 13A.