Hot Tub

[Bri.James]

Ok here goes, ready, steady...................... GOoooooo.

Ok advise time.

Been out of the electrical game now for over 20 years no interested in returning as I'll basically have to start from fresh anyway question.

Installing a hot tub in my summer house with its own feed and I cant remember what's what so hence why I'm here.

The tub is rated at either 16amp or 32amp dependent if you want to run the heater with the blower so my plan is to run it as 32amp as follows...

Old type rewritable DB protected by RCD with a spare carrier, this spare I'm going to use a 32amp MCB and run 10mm 6242Y T&E up from the DB into the attic, through the attic and terminated feeding armoured SWA.

Now specs says that if the "Above a plasterboard ceiling covered by thermal insulation, insulation thickness greater than 100 mm" then the 10mm is sufficient the run length in 6242Y is 20mtrs and armoured outside clipped is 15mtrs terminated into a Locking Off Safe Shut Down - IP41 IP65 isolator.

The calcs says:

70°C Thermoplastic Insulated and Sheathed Flat Cable with Protective Conductor
Tables Apply to: 6241Y, H6242Y, H6243Y

Voltage: 230V
Load: 7.36kW / 32A
Length: 20m

Method of Installation: H6242Y ONLY above a plasterboard ceiling covered by thermal insulation exceeding 100mm in thickness

Cable Size: 10mm²

And....

Multicore 90°C Armoured Thermosetting Insulated Cables
Tables Apply to: H6942XL, H6943XL, H6944XL, H6945XL, Tuff Sheath,

Voltage: 230V
Load: 7.36kW / 32A
Length: 15m

Method of Installation: Clipped direct

Cable Size: 2.5mm²

So would I be ok to carry out the above?

Or can anyone that's up to date enlighten me?

Regards

 

[foxhole]

Are you sure blower and heater run together?, my tub is configured to shut off heater if blower is in use. Heater normally runs with the pump at low speed when tub is not occupied.

 

[Bri.James]

The supplier has said there are two ways to wire the tub 16amp so it runs heater and when blowers are turned on the heater goes off and at 32amps you can run both at the same time.

The tub is the Passion Refresh and different suppliers quote different ratings 16amp, 20 and 32 so I'm covering my arse with 32 just in case.

 

[EFLImpudence]

Now specs says that if the "Above a plasterboard ceiling covered by thermal insulation, insulation thickness greater than 100 mm" then the 10mm is sufficient

Maybe - but there is the option of not installing it that way.

Otherwise it seems alright.

Is there any point using 90° cable?

 

[Bri.James]

I'm not looking at the temp ratings that's what showed up on the calcs used I'm more interested in the end result.

 

[Bri.James]

The reason for 3242Y is I can hide it in trunking when it drops from the attic through the bedroom and then to the DB and if I use armoured its more a hassle to bend and hide.

 

[ban-all-sheds]

Is there any point using 90° cable?

Not when you can't run it at 90° because nothing you connect it to can run that hot.

 

[Bri.James]

Yep.

 

[EFLImpudence]

I'm not looking at the temp ratings that's what showed up on the calcs used I'm more interested in the end result.

I expect that is because 70° has a rating less than 32A; 90° only just enough.

I think you will need 4mm².

Having said that, I presume you just worked out the 7.36kW as the maximum for 32A @ 230V.
What is the actual rating of the tub?

 

[ban-all-sheds]

So would I be ok to carry out the above?

Does your "OK" encompass the requisite Building Regulations approval for the new circuit?

Or can anyone that's up to date enlighten me?

http://electrical.theiet.org/wiring-matters/63/hot-tubs/index.cfm

 

[Bri.James]

Part P applies to electrical installations located in outbuildings such as detached garages, sheds and greenhouses.

Notifiable work includes new installations, house re-wires, and the installation of new circuits. Notifiable work also includes additions to existing circuits in kitchens, bathrooms, outdoors and in other special locations. (See question 5 note 5.)

What types of electrical work are 'non-notifiable'?
The following types of work are non-notifiable:

• Replacing accessories such as socket-outlets, control switches and ceiling roses
• Replacing the cable for a single circuit only, where damaged, for example, by fire, rodent or impact (1)
• Re-fixing or replacing the enclosures of existing installation components (2)
• Providing mechanical protection to existing fixed installations (3)
• Installing or upgrading main or supplementary equipotential bonding (4)
• Work that is not in a kitchen or special location and does not involve a special installation (5) and consists of:
  - adding lighting points (light fittings and switches) to an existing circuit (6)
  - adding socket-outlets and fused spurs to an existing ring or radial circuit (6)
  

Where As Ive said been out of the game for over 20 years I intend to get the circuit commissioned and signed off I'm just laying down the ground work ready.

 

[EFLImpudence]

Part P applies to all work in dwellings.


New instructions 2013 in England -

http://www.legislation.gov.uk/uksi/2012/3119/regulation/6/made
New circuits are notifiable.



Still the same as before in Wales

 

[Bri.James]

What baffles me is even the smallest Hot Tub would usually require at least a 16 amp supply and bigger Hot Tubs with 3 pumps or more generally require a 32 amp supply.

So the tub I'm getting has only one 3hp pump and a majority of suppliers quote 16amp so am I being an "Overkill" running a feed just in case it is indeed 32amp needed?

 

[flameport]

I intend to get the circuit commissioned and signed off I'm just laying down the ground work ready.

That isn't how it works.
The new circuit you are proposing is notifiable.
There are 2 realistic options:
1. Notify building control, pay the fee, find out what testing they want, and then install it.
2. Have someone registered with a Part P scheme to install it and do the notification through the scheme.
Doing some/all of it yourself and 'signing it off' later is not an option.

The only other choice is to use a 3rd party certifier, which goes along the same route as 1, except you are paying someone else for the notification and testing / inspection.
However there are very few third party certifiers, and paying one of them isn't likely to be much different from paying building control.

 

[ban-all-sheds]

I intend to get the circuit commissioned and signed off

Be aware that Building Regulations certification doesn't work like that.

I'm just laying down the ground work ready.

Talking of ground work...

Unless you like digging trenches, why worry about using a cable which might be too big now? You might get a bigger tub, you might add on a sauna - who knows.