A hot tub like no other

[grumpyjohn01]

Hi All, Havent posted for a while but would appreciate some opinions..
See pics for hot tub arrangement that I've been asked to provide power for..
A local tradesman had already built this when I was brought in and the clients are existing customers of mine who had booked in lots of other work.
He has used 2 plug and play pump/heater sets that are coupled together in some way and all the pipework within the structure is plastic apart from 2 copper bends as seen in pic.
I have provided power into several adjacent buildings from a remote 3 phase incoming supply. The whole site is on TT earthing.
The structure sits on a steel reinforced slab and is constructed of concrete / natural stone / brick.
There will be no class 1 equipment in zones 0 or 1 (sec 702 applies I'm sure) but I'm sure there will be plugged in stuff everywhere , they are party types and have 4 sons teens/20s.
Bonding..? rebar in slab is inaccessible (builder told me he'd get to it but hasn't yet) but I'm sure it will be an extraneous conductive part..the copper bends are not as tested today but when everything is wet?
In short I have concerns that the design is a bit of a lash-up but need to do the right thing...should I bond or not?
Forgot to say the thing is surrounded by wooden decking which 1 of the sons has peppered with mickey mouse LEDs, thankfully SELV. Cheers John

 

[buzzlightyear]

Is it a hot for the ducks. Lol.

 

[grumpyjohn01]

? I hate hot tubs at the best of times but this one takes the cake, its leaking like a sieve anyway so hopefully demolition followed by the installation of something more...er....plastic

 

[littlespark]

home brew hot tub.... dodgy AF

Whats the twin and earth just dangling in beside the pipework?
And speaking of which.... the pipes arent lagged... any hot water is going to be cooled before it gets to the duck pond

Why didnt they just buy a proper tub and build the tiki hut around it

 

[Dartlec]

Not sure which is worse the DIY plug in hot tubs that are US made and don't always make it clear when they need bonding, or a 'kit' put in by a builder like this.

Presumably he didn't employ a plumber, looking at all that push fit mess?!

Definitely one for more expert input, but my 2p from a first look...

I don't think the 2 copper bends would need bonding, given all the plastic pipe supplying it...Is it plastic from the source too, or is there copper in that shed?

Rebar might be a different matter and could be tested, but I'd probably supplementary bond it.

As you say, almost certainly they are going to want to plug things in, so I'd be tempted to maybe put in RCD socket(s) in an appropriately compliant place, (maybe 10mA?) in addition to whatever RCD is protecting the supply...

As well as a big sign that says 'DO NOT CHARGE PHONES IN THIS HOTTUB"

 

[pc1966]

If it were me then I would be looking at bonding the rebar or putting in a local earth rod to supplement the main TT earth. In most cases more rods are better!

I think @Dartlec idea of having a couple of 10mA RCD outlets as well as the normal 30mA "additional protection" on the supply side is a very good idea. Even if a supply RCD fails they still have some means of disconnection. The likes of MK make them such as this model:

MK-Electric

Monitor and control plug-in equipment to reduce energy consumption.

www.mkelectric.com

Though quite a few sellers seem to have it listed as 30mA?

Not sure if you get IP65 rated versions, but you might be able to fit on in a IP65 enclosure.

 

[pc1966]

Same for PowerBreaker/GreenBrooke they offer white and metal-clad versions such as these:

Greenbrook K22WPAAN10-C RCD PowerBreaker ACTIVE Range Twin Switch Socket 10mA - White

Electrical2Go Sell Discount Greenbrook K22WPAAN10-C RCD PowerBreaker Twin Switch Socket for Both Trade & Home Use. Big Name Brands, Free Delivery.

www.electrical2go.co.uk

Greenbrook K22MPAAN10-C RCD PowerBreaker ACTIVE Range Twin Switch Socket 10mA - Metal Clad

Electrical2Go Sell Discount Greenwood K22MPAAN10-C RCD PowerBreaker Twin Switch Socket for Both Trade & Home Use. Big Name Brands, Free Delivery.

www.electrical2go.co.uk

 

[grumpyjohn01]

Thanks for all the replies.
I am erring on the side of bonding the rebar, if I can get access to it...the builder assured me at the beginning that he could get at it but is now back pedalling..the pipe bends are over 1/2 a Mohm so not really worried about those, tub supply has its own stake that I fitted already with a pretty low Ra (12 ohm).
Great info about the 10mA RCD sockets, hadn't realised they were available, I have already fitted 2 x single IP rated Sockets in the shed behind hanging off a 30mA RCD but they are BG so should be able to retrofit a standard faceplate socket, if they are available as singles , will have to have a look. The dangling T&e is connected to a bulkhead light fitted by the builder, I was picking my battles with that one but it won't make the final edit...!
As far as heat loss goes, a heating engineer friend says it will be considerable!!

 

[grumpyjohn01]

Why didnt they just buy a proper tub and build the tiki hut around it

Very good question....

 

[buzzlightyear]

good question

Me I think they are qackers for not putting in a pond of the wild life, it must be them then.

 

[pc1966]

Me I think they are qackers for not putting in a pond of the wild life, it must be them then.

I thought hot tubs we all about "a pond of the wild life"?

Or as a friend of dubious reputation told me, "pervert soup". Alas, I was in the tub at that time, make of it what you will...

 

[Dartlec]

Thanks for all the replies.
I am erring on the side of bonding the rebar, if I can get access to it...the builder assured me at the beginning that he could get at it but is now back pedalling..the pipe bends are over 1/2 a Mohm so not really worried about those, tub supply has its own stake that I fitted already with a pretty low Ra (12 ohm).
Great info about the 10mA RCD sockets, hadn't realised they were available, I have already fitted 2 x single IP rated Sockets in the shed behind hanging off a 30mA RCD but they are BG so should be able to retrofit a standard faceplate socket, if they are available as singles , will have to have a look. The dangling T&e is connected to a bulkhead light fitted by the builder, I was picking my battles with that one but it won't make the final edit...!
As far as heat loss goes, a heating engineer friend says it will be considerable!!

Looks like Greenbrook do make a single - expensive in some places, but being sold off here:

https://www.electricalcounter.co.uk...et+Slim+Profile+Switched+10mA+230V/1856694772

Also seems to be a Type A (or claims to be responsive to pulsating DC at least)

The MK 1 gang is still on a 2 gang front for whatever reason....

 

[grumpyjohn01]

just to clarify, were you meaning use the 10mA sockets for the hot tub (2 x 13a) supplies or sockets to be used in the vicinity (within the confines of 702) ?

 

[grumpyjohn01]

I mean installed in accordance with sec 702

 

[buzzlightyear]

I thought hot tubs we all about "a pond of the wild life"?

Or as a friend of dubious reputation told me, "pervert soup". Alas, I was in the tub at that time, make of it what you will...

wash your dirty mind with the a bar of soup .lol.

 

[Dartlec]

just to clarify, were you meaning use the 10mA sockets for the hot tub (2 x 13a) supplies or sockets to be used in the vicinity (within the confines of 702) ?

The pumps are remote (in the shed) I assume?

I was thinking 30mA at the source, then 10mA at any sockets , as a double protection just in case an RCD fails. Exceeds the 7671 requirements, but seems like a sensible precaution given the circumstances.

Though still worth making it very clear that nothing should be plugged in and used in the tub itself - most things will be SELV I guess, but who knows what quality the transformers will be...

 

[UNG]

That tub looks like something that hasn't been properly thought out, looking at it one thing I doubt is that it will be hot it might get luke warm but even that is being optimistic as it doesn't look as if it has any insulation between it and the concrete base