hot tub in a large summer house

[bigspark17]

got a hot tub to conect in a summer house 10m from a house. customer has put a 3c swa 6mm in a duct ready. i was going to 100ma rcd/ 32 amp mcb inside the house which is tncs. then at the summer house put a 4way board 30ma rcd main switch with hot tub, lights, outside socket coming off this db . i was going to tt this board so that everything in the summer house and ground earth was at the same potential.. any better suggestions or comments apprechiated.!

 

[RyanCheetham]

I thought hot tubs needed rotary isolators? And you could get nuisance tripping with the double rcd on the swa. Why not use a regular incomer on the shed fuse board and rcbo the seperate circuits?

 

[malcolmsanford]

Well I certainly would not be putting an RCD on a SWA on a TNC-S it is not required.

I agree that for this I would make the installation a TT, you may find that the hot tub will call for it's own earth rod as well

 

[bigspark17]

the hot tub will have a rotary switch adjacent to the machine (sorry forgot to put that thought it was pretty obvious tho) .. the hot tub is in a wooden summer house has a floating wood floor mounted on a concrete base.. regarding an individual rod for the tub i considered this, if i was to do this i could just tt the tub at the rotary and keep the couple of lights and outside socket on the tncs earthing arrangement from the house.?

 

[worzol99]

What rating is the hot tub 32a seems low for a supply to this and socket, lights etc

 

[bigspark17]

hot tub installer wanted 32A supply.. customer wants 2 small LED background lighting the oudide socket may never get used apart ftom maybe a lawn mower but he wont b mowing lawn and in hot tub same time .. i realise being a tncs system supply from the house the armoured doesnt require rcd protection but with a 100ma upstream from the 30ma i cant see you the 100ma would go before the 100ma unless there was leakage on the swa, then i would want it to trip.!!

 

[keniff]

That was my trail of thought but it needs to be an s type rcd or either could trip first, that's my experience anyway

 

[Taylortwocities]

That was my trail of thought but it needs to be an s type rcd or either could trip first, that's my experience anyway

Yes But there is absolutely no reason to RCD protect the SWA in the first case.

But, if you must double RCD it (and I've said it before) you can only discriminate with RCDs using time, not current.
So time delay RCD (S type) at origin and 30mA at the tub.

 

[Richard Burns]

got a hot tub to connect in a summer house 10m from a house. customer has put 3c swa 6mm2 in a duct ready. I was going to 100ma TYPE S rcd/ 32 amp mcb inside the house which is tncs (or no RCD just mcb and terminate earth at remote CU). Then at the summer house put a 4 way board with 30ma rcd main switch with hot tub(hot tub installer wants 32A supply but you are also using it for other circuits?), lights(6A), outside socket (16A) coming off this db . I was going to tt this board so that everything in the summer house and ground earth was at the same potential..sounds OK any better suggestions or comments appreciated.!

Comments above and I would tend to put in a 45A at the supply so you have some leeway.