Some advice on electrical please

[amcjam]

I'm putting a sauna in the garage 4.5kw,
Electrics in garage now is the following:
Consumer unit 1x16a mcb feeding 1 double socket
1x6a mcb Feeding 1 fluorescent light
Can I change the 16 mcb's house and garage to 20a mcb's and fit a changeover switch for the socket and sauna.

Thanks in advance

Amc

 

[Gossy]

What size is the cable and MCB from the main consumer unit to the garage consumer unit, is there an RCD in the main consumer unit?

 

[Yellow Peril]

Same basic maths 4.5kw / 230 v. =. 18.5 amps Your call

 

[Myke Rocks]

I'm putting a sauna in the garage 4.5kw,
Electrics in garage now is the following:
Consumer unit 1x16a mcb feeding 1 double socket
1x6a mcb Feeding 1 fluorescent light
Can I change the 16 mcb's house and garage to 20a mcb's and fit a changeover switch for the socket and sauna.

Thanks in advance

Amc

Technically correct answer: I do not know if you can or not.

Answer to the question you are not asking but should:

2.5sq cable used for sockets is rated at circa 21a. Since your garage is probably fed by such a cable, a 20a mcb on the supplay is ok in place of a 16a one.
I suggest keeping the garage socket circuit as is, and fitting an additional 20a MCB to the garage distribution board for the sauna.
Be sure the sauna is RCD protected. This may be fitted in your house already. If not, fit a 20ma RCD in the garage distribution board.
Yes, you could fit a changover switch, but why bother?
If you overload the incoming supply, the 20a mcb you are going to fit will trip. That's what it will be there for.
Myke

 

[morty]

i presume you don’t want to have your sauna in the dark??don’t forget by the time you add lighting not including whats there already etc,etc there goes your max limit.any extraction being used?not enough detail on the job.

 

[AberdeenAngus]

Nope, suspect you'll need a dedicated feed with a 32A breaker for that.
Have a word with Den. He'll sort you out.
Tis not a thing for the inexperienced.

 

[JumboSi]

Definitely not for the inexperienced. The cable size, the length of the run of cable from the house CU to the garage CU, the rating of the appliance and the way in which your system is earthed all have an effect. Anything above 3.5kW has to be hard wired in to the system and, as has been said above, this is over 19 Amps of load. Also, saunas have the potential to leak current to the extent that they are substantial contributors to RCD trips in the CU. I would quote a job like this based on installing a 6mm sub main running to the garage CU, ie bypassing the main RCD. Depending on the site this might require steel wire armoured cable and a trench to lay it in, maybe. The garage CU would need RCD protection and I'd run the sauna via a 20A CB using 2.5mm cable. The other services I would use probably one circuit on a 16 Amp CB operating the light via a switched fused spur.
These situations are immensely site affected, just to give you an idea, I did one job where I had to use 16mm SWA to run such a sub main, to a higher load, I grant you, because the outbuilding was so far from the house.


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