Hot tub install

[Sb8389]

Hey guys
This may have being touched on before.
I have got to install a 32amp Hot tub for a customer.
The installation is a dual RCD board
TNCS
All bonding in place.
I am going to install a 6mm 3core armoured surface cleated to garage wall and the hot tub will be installed behind the garage where I will put in a 32amp rotary isolator.
I have heard many discussions on weather acceptable to export the PME and you should TT the hot tub in case of loss of neutral and the potential dangers that could arise, now I’m not sure if the hot tub is class 2 although speaking to the manufacturer they have said the frame is metal but the actual surroundings and the centre are all plastic.
What’s your thoughts and past experience on what you do with these installs

Thanks

 

[buzzlightyear]

no you do not require a TT for that ,just wire in normal .

 

[MFS Electrical]

Where did the whole hot tub earth rod argument appear from?
I'm still to be convinced either way. Both sides have good points.
Buzz, any chance of some enlightenment as to why you think its not needed?
and is there actually any regs to say that it would be required?
I know about the reg talking about exporting PME but to be honest I'm not convinced that's what's meant by it.

 

[remedial]

what does the manufacturers instructions say?

 

[telectrix]

what does the manufacturers instructions say?

if sold in Wales, MI will probably say "this is not a sheep dip".

 

[davesparks]

Where did the whole hot tub earth rod argument appear from?

It comes from the regulations and guidance notes.
The guidance notes advise that an indoor hottub should be treated as a bath and an outdoor hottub should be treated as a swimming pool.

There is a note in the regulations advising the connection of a suitable earth electrode (I believe less than 21 ohms is mentioned) to the equipotential bonding system of a TNCS supply for outdoor swimming pools.
People misread this advice as saying it should be seperated from the earthing system and a TT system created. If you actually read the note it does not say this, it advises the connection of an earth electrode to the equipotential bonding system. That is to say connecting an earth electrode of suitable Ra to the MET in addition to the connection to the TNCS earth.

 

[MFS Electrical]

It comes from the regulations and guidance notes.
The guidance notes advise that an indoor hottub should be treated as a bath and an outdoor hottub should be treated as a swimming pool.

There is a note in the regulations advising the connection of a suitable earth electrode (I believe less than 21 ohms is mentioned) to the equipotential bonding system of a TNCS supply for outdoor swimming pools.
People misread this advice as saying it should be seperated from the earthing system and a TT system created. If you actually read the note it does not say this, it advises the connection of an earth electrode to the equipotential bonding system. That is to say connecting an earth electrode of suitable Ra to the MET in addition to the connection to the TNCS earth.

Nice one very informative. Which guidance note is this in?

 

[Midwest]

No personnel experience myself, but having read quite a few threads on the subject, I think a lot depends where the hot tub is installed, not withstanding #6. That is if its going inside a wooden shed or on decking, to just being sat on the lawn.

 

[sinewove]

It comes from the regulations and guidance notes.
The guidance notes advise that an indoor hottub should be treated as a bath and an outdoor hottub should be treated as a swimming pool.

There is a note in the regulations advising the connection of a suitable earth electrode (I believe less than 21 ohms is mentioned) to the equipotential bonding system of a TNCS supply for outdoor swimming pools.
People misread this advice as saying it should be seperated from the earthing system and a TT system created. If you actually read the note it does not say this, it advises the connection of an earth electrode to the equipotential bonding system. That is to say connecting an earth electrode of suitable Ra to the MET in addition to the connection to the TNCS earth.

So if the RA of 21ohms can,t be obtained the tub would be TT,ed,if outdoors?
Regards,S

 

[davesparks]

So if the RA of 21ohms can,t be obtained the tub would be TT,ed,if outdoors?
Regards,S

No, it doesn't give any advice on what to do if the Ra of 21ohms isn't achieved. That would be up to a technically knowledgeable person to decide how best to proceed.

 

[Ian1981]

Nice one very informative. Which guidance note is this in?

Gn7 special locations
It gives guidance to other types of installations that are not necessarily special installations or locations but can be treated as such if the installer/designer chooses, like a hot tub is advised to comply with section 702 , swimming pools.

 

[littlespark]

Or you buy a hot tub from Homebase or Tesco’s or whatever and plug it into an extension lead out your kitchen window.

I’ve seen inside one of the 6 seater tubs that need a 32A supply. Has an rcd behind the control panel which needs a screwdriver to open to reset the thing.
Not very user friendly. I see joe public just leaving the panel loose so it’s easier next time.