Discuss A 32amp hot tub and a 40amp sauna on a regular, domestic 80amp supply in the Electrical Forum area at ElectriciansForums.net

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Hi all

I’m new here so hello and thanks for looking.

I’m looking for what is, I’m hoping, a quick bit of advice.

I’m having an 8kW sauna heater fitted and also want to buy a hot tub. I’m going to get someone in as I need a new circuit, consumer unit etc. But hot tubs have a long delivery wait time at the moment so I want to get on and order one.

I’ve got the option of a plug and play type hot tub which just plugs in a 13amp plug or the superior 32amp tub which obviously has its own circuit and draws more power. I think the 13amp ones maybe pull 2kw and the 32amp about 4.5kw

My question is: The hot tub will always be on so it will inevitably be on at the same time as the sauna for periods. Is this going to be too much on a regular domestic supply with the 32amp hot tub? If it even could be a problem, I’ll just order the 13amp but I’ve no idea. Oh, the main fuse coming in is 80amp.

Thanks.
 
TL;DR
32amp hot tub on at the same time as an 8kW sauna heater. 80amp fuse incoming. Single phase supply. Is this too much?
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telectrix

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one solution would be a changeover switch. hot tub on normally, and the switch would switch off the hot tub when you wanted to use the sauna. then switch back after.
 
What other large load items do you have on the consumer board? Ovens/induction cooker/shower etc. How big is the house? 2/3/4 bed?
 
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  • #5
Thanks guys. I’ll answer all in one post if that’s ok. Tbh we are probably a large load household. 4 bedrooms, 2 kids with computers on both with big TVs, the lounge has a big tv and big amp for the sound (which someone will be using even if I’m in the tub). Electric oven which could possibly be switched on when everything else is happening. On the plus side, Philips hue low energy lighting everywhere, oh and a gas hob

Aside from a switch as suggested, which I’m not sure about as I can see me jumping out of the sauna and into the tub (via a shower - on a saniflo 🙈) I’m getting the impression that my options here are the 13amp or upgrading to 3-phase - am I feeling this right?

I’m not too bothered if it has to be the 13amp, you can probably direct all the pump power into one seat for a bit for a better massage. Won’t be the end of the world but if I could, I’d get the 32amp.

Thanks again.
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Oh and there is an electric shower here but it’s coming out for a mixer shower so I can bring that forward.
 

James

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the electrician responsible for the installation of these items should be able to do some calculations for you.

it is not as simple as adding up the amps suggested for supply.
work on 4A per Kw
even if the 8 kw sauna is on and the 4.5Kw hot tub is on and they are both pulling maximum power then the total requirement is likely to be under 50 Amps

best guess is you will be fine, however it is down to the spark installing to calculate and certify.
 

James

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Thanks, that sounds positive. Not impossible then.
It may be running a bit close to the wind but my best guess is that you will be fine.

Can’t give a definite answer without knowing the whole installation.
And to be fair, it’s not my word that matters, it’s the spark installing that will have to sign it off as compliant.
However I see no problems.
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nothing is impossible to an electrician, except possibly giving a plumber an IQ in double figures.
You can get to ten just using your fingers and thumbs,
Oh sorry you were on about IQ not counting!!

Not so sure now.
 
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  • #10
Thanks all. Sounds like I’ve got 3 options. Wait until I’ve had someone here before ordering, be on the safe side and order the 13a or take a gamble and order the 32a with my fingers firmly crossed!
 

telectrix

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first option is the best.
you'd think the 13A would cost less to run but that's wrong. the 32A option will draw more current, but will be heating for less time. basically you need to put in the same amount of electrical energy in both cases. just saying.
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If it is worked out and there is a problem with demand, then maybe a priority switching unit could be used like this:


these switch off one of the loads if the priority load is taking more current
see post #2. :sunglasses: .
 
first option is the best.
you'd think the 13A would cost less to run but that's wrong. the 32A option will draw more current, but will be heating for less time. basically you need to put in the same amount of electrical energy in both cases. just saying.
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see post #2. :sunglasses: .
Doh, sorry I thought you meant a manual change over switch
 
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  • #14
Thanks all. Telectrix, I realised there’d be no energy saving, the 13a will just take longer getting up to temperature, I guess the extra pumps will use more energy on the 32a but you do get benefit from this extra energy. With the priority switch, does this automatically knock one thing off when another is switched on or do you operate it manually? Also, if I used a priority switch, could both items be connected to the same supply on the same rcd? Also, are these switches expensive? I’m minded to consider this further tbh and I guess it would be no problem to switch the sauna off to jump in the tub for 20 mins and then back. Both would probably retain sufficient heat between uses.
Thanks again.
 

7029 dave

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Those priority boards look just the job.
Today's electrical accessories have come along way over the decades.
 
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