Hot Tub Wiring

[Morph123]

Hi All,

A quick question for which I am hoping someone can give a quick response..please.

I am setting up the installation for a new hot tub, I have an electricial coming out to wire into the Consumer board for me once I have the wiring in place to ensure Part P compliant.

The tub is rated 20amp which I am told will need 2.5mm T&E from the consumer unit (wired into the RCD side of the busbar!), I have a length of 6mm T&E can I use this instead?

I need to install a 20amp isolator, can I install this indoors rather than outside, it would be located on the wall inside a door around 2 metres from the hot tub which is outside?

From the isolator I will wire a length of 20amp armour cable through the wall to the outside where the hot tub is.

Thanks
Kevin.

 

[ColJack]

nothing at all wrong with using larger cable than is needed.. you might want to check the spec's of the isolator thought to make sure it can take 6mm cable..

if you're having a sparky come out to wire it for you then the best bet is to ask him what he wants and where since it's his ass on the line once he's signed..

one question I would ask though is would the isolator be easilly accessible?

you sure it's only 20A?
that doesn't sound like much for a hot tub with heating, lighting and pumps..

 

[Morph123]

Thanks for the confidence boost about the 20amp hot tub I've just spent £4500 on....I am sure it's 20amp, it's got a single 2.5HP pump and a 3kw heater with a few LED type lights sprinkled around it and a iPod connection and speakers!

The isolator would be easily accessible and I was thinking the switch is a lot easier to operate than one of the rotary type isolators that go outside?

I was going to get the electricial to do the whole job but he doesn't have the time and I offered to do everything but the hook up to the consumer unit, he said this was fine and told me 2.5mm but I have a length of 6mm.

Thanks for speedy response.


Kevin.

 

[ColJack]

2.5HP = 1.9KW ( close enough. )

4.9KW / 240V = 20.4A.. so it's just over the 20A... not counting the bells and whistles of the LED's and IPOD dock..

might need 25A breaker.. or if you're installing 6mm then go for 32A..

 

[dave68]

2.5HP = 1.9KW ( close enough. )

4.9KW / 240V = 20.4A.. so it's just over the 20A... not counting the bells and whistles of the LED's and IPOD dock..

might need 25A breaker.. or if you're installing 6mm then go for 32A..

with most hot tubs when pumps are running , heater switches off and then back on when pump turned off. as pointless trying to heat water traveing through heater at xxxx speed per minute

 

[electronicsuk]

2.5HP = 1.9KW ( close enough. )

4.9KW / 240V = 20.4A.. so it's just over the 20A... not counting the bells and whistles of the LED's and IPOD dock..

might need 25A breaker.. or if you're installing 6mm then go for 32A..

with most hot tubs when pumps are running , heater switches off and then back on when pump turned off. as pointless trying to heat water traveing through heater at xxxx speed per minute

How do you figure? I've never owned, operated or had the pleasure of sharing a hot tub, but I do remember a little physics from school. If the water isn't being pumped over the heating element then surely this will prevent the water from being heated in an even fashion? What's more, if you're putting in 3kW of electical energy into the element then it has to go somewhere, in this case the water, regardless of the flow rate across the element. Too little flow and the water will boil, but in a closed system such as a hot tub, there is surely no upper limitation on flow rate.

 

[sparkyspike]

If the hot tub instructions specify 20A, then use a 20A supply. You can have a double pole 20A switch indoors running from a 20A breaker. I would still recommend a rotary isolator outside. The good thing about these is, as well as being accessible because they're in the same space as the hot tub, they are usually lockable which is handy for kids/maintenance etc. Also, as you are using 6mm cable to it, you can fit a 32A isolator (which will do the same job) which will mean you can upgrade/add to your existing hot tub without having to change the wiring inside.

2.5mm cable will be ok for a 20A breaker (unless you're running for 30m or so!). 6mm will obviously be ok too, although it would be easier to wire it into a rotary isolator than a 20A DP switch.

PS, don't worry - hot tubs are much more efficient nowadays, 20A is fine.

 

[mattysupra]

i think mine pulls 38 amp when fully running. It does however have 3 pumps + 3kw heater + blower +the led lights + t.v/dvd (the t.v/dvd set on FIRE so no longer working)

The heater is normaly located on a seperat pump that is part of the filtering system. This is always running, even when off and set in ECO mode etc.

I would be supprised that you have one pump doing filters/ heating / jets etc. by the time it has passed through the filter, the jets will be about as powerfull as a Hamsters fart!


If however it does all run of one pump, i think i would be swapping the fancy crap that breaks after 2 weeks for some more pumps!


Out of intrest, how many jets does it have?

 

[ban-all-sheds]

I knew someone once who bought a house with a pool, and very excited he was by it.

He was less excited when he contemplated the gas bills for the 250,000 BTU boiler which heated it...

 

[bernardgreen]

Speaking with my old first aid / accident recovery hat on the isolator for an outdoor pool / hot tub should be obvious in case it has to be found by emergency people arriving to deal with an accident.

It isn't "law" but it does make it easier to react knowing that the area is (probably) safe from electrical shock hazard.

 

[Morph123]

Thanks everyone for the advice.

I have just completed the install;

32amp MCB, from this 6mm T&E to rotary 32A 3 pole isolator 3 metres away then 2.5mm 3 core armoured cable from isolator through wall to hot tub located outside about a metre from exit of cable.

Just waiting for electrician to visit and connect to consumer unit on the RCD side.

The instructions for the isolator were non existant, but the earth from each cable is on a 2 screw connection next to the Neutral connection again both Neutrals and the lives go either side of the 3 pole switch, elected T2 on both sides, assuming now I could have got away with a 1 pole switch or the live and earths should go into the other 2 terminals on the switch?? I have just realised that my mistake here is that the earth, live and neutral go into the central switch so they are all isolated, the extra connections on the inside threw me, still don't understand why they are there??

Rgds
Kevin.

 

[bernardgreen]

I have just realised that my mistake here is that the earth, live and neutral go into the central switch so they are all isolated

YOU DO NOT ISOLATE THE EARTH....... That MUST remain connected and continuous at all times.

 

[ElectricDunc]

2.5mm on a 32A supply? Even if it is an armoured cable that sounds a bit small. The isolator is designed to disconnect both live and neutral. Double pole isolation is mandatory in this case. The earths are never switched so must be permanently connected together and never via a switch. In my opinion the isolator should be external to the property as well. What would happen if the house was locked, you couldn't isolate the supply to the hot tub in an emergency.

Oh and did you remember to earth the armouring of the cable?

 

[Morph123]

Right, I have now put the earth back to the permanently joined connector.

I know the 'ideal' is to locate the isolator, but it is very easy to locate, the armour cable leads the way and it is no more difficult to find than if it was located outside (first thing you see on wall inside rear door of garage) and HOT TUB written on it. There is no chance of door being locked as we leave it open (in this day and age I know!).

Whilst it is a 32 amp supply from the consumer box to the isolator from then on I have used 2.5mm cable from this point onwards as the tub needs a 20amp supply. In any case the 2.5mm cable I purchased states it is rated at 36 amps.

Rgds
Kevin.

 

[ban-all-sheds]

Right, I have now put the earth back to the permanently joined connector.

So, basically, you decided you could tackle this job even though you must realise that you don't know what you're doing, and your ignorance is such that you didn't realise how dangerous and illegal it is to switch the earth.

Whilst it is a 32 amp supply from the consumer box to the isolator from then on I have used 2.5mm cable from this point onwards as the tub needs a 20amp supply.

It's an isolator - it doesn't do any fusing down!

In any case the 2.5mm cable I purchased states it is rated at 36 amps.

Really?

At what temperature?

And for what installation method?

You see, because you decided it would be OK for you to design circuits even though you don't know how to do it, you've gone wrong.

I have an electricial coming out to wire into the Consumer board for me once I have the wiring in place to ensure Part P compliant.

Given the mistakes you've made due to your ignorance, don't be surprised or disappointed if he won't connect anything up.

And did you actually notify LABC in advance about this work? If so, what did you tell them you'd be doing to comply with P1?

What do you expect to happen now that you've failed to comply with it?

If you didn't notify, just what are you expecting this electrician to do to in terms of "ensuring compliance"?