Hot tub help!

[Pauldicker]

I have been asked by a customer to quote for the wiring to a hot tub. I have not done one yet so some advice would be appreciated.

consumer unit is a lewden, i plan on using 6mm 3core swa (max distance 20m) to a weatherproof isolator, then to a female blue commando socket required by the company. Can only find ip44 at present looking for an ip56 as it will be outdoors albeit under a lean too.

so here's the question the company want provided a 16A mcb/rcbo type c,
I cannot seem to find a type c Lewden rcbo , is there a compatible brand?
Am I correct in thinking that the commando socket has to be at least 2.5 m away from tub as per 17th edition for swimming pools. Or more than 2.5 m high?

Anything else I need to consider.

 

[Brightspark2]

What about putting a 16A C MCB in db then out to an RCD in a separate enclosure adjacent to db?.

As you shouldn't really be mixing manufacturers of mcbs and dbs.

 

[Pauldicker]

What about putting a 16A C MCB in db then out to an RCD in a separate enclosure adjacent to db?.

As you shouldn't really be mixing manufacturers of mcbs and dbs.

Its an idea. I could install a separate consumer enclosure and make it completely independent including separate tails, like a shower unit.

 

[davesparks]

If installing a commando socket you could use one which includes and RCD in it.
An IP56 commando socket will not achieve any more than an IP44 one unless they fit an IP56 plug. If they only fit an IP44 then it won't have the locking collar etc which give the added IP

 

[Pauldicker]

If installing a commando socket you could use one which includes and RCD in it.
An IP56 commando socket will not achieve any more than an IP44 one unless they fit an IP56 plug. If they only fit an IP44 then it won't have the locking collar etc which give the added IP

If I did that would it then mean that I could just use a 16a mcb in db. There is no rcd on db as they are all on rcbo's.

would this method still meet 7671?

 

[Brightspark2]

If I did that would it then mean that I could just use a 16a mcb in db. There is no rcd on db as they are all on rcbo's.

would this method still meet 7671?

Yes as you would be providing RCD protection on the socket outlet.

You need to check if the circuit needs additional protection too though. Does it?...

 

[davesparks]

If I did that would it then mean that I could just use a 16a mcb in db. There is no rcd on db as they are all on rcbo's.

would this method still meet 7671?

Without knowing the earthing system I couldn't say for definite.
It is up to you as the designer to decide whether it meets 7671 or not.
What I don't understand is why you want to install an isolator and a socket? Why not just one or the other?

 

[Pauldicker]

Without knowing the earthing system I couldn't say for definite.
It is up to you as the designer to decide whether it meets 7671 or not.
What I don't understand is why you want to install an isolator and a socket? Why not just one or the other?

Its a TNS, the isolator idea was for servicing, but then all they have to do is pull out the plug, I've not used a commando socket, and with the existing consumer unit I am unable to get a manufacture rcbo, and because it's a new circuit I know it needs to be rcd protected. Although the socket outlet may be rcd protected the cable between db and socket won't be.

just after advice if anyone has fitted them before.

 

[Leesparkykent]

Its a TNS, the isolator idea was for servicing, but then all they have to do is pull out the plug, I've not used a commando socket, and with the existing consumer unit I am unable to get a manufacture rcbo, and because it's a new circuit I know it needs to be rcd protected. Although the socket outlet may be rcd protected the cable between db and socket won't be.

just after advice if anyone has fitted them before.

Use an installation method that doesn't require RCD protection and use a unit at the far end with a combined RCD and commando socket.

 

[davesparks]

Its a TNS, the isolator idea was for servicing, but then all they have to do is pull out the plug, I've not used a commando socket, and with the existing consumer unit I am unable to get a manufacture rcbo, and because it's a new circuit I know it needs to be rcd protected. Although the socket outlet may be rcd protected the cable between db and socket won't be.

just after advice if anyone has fitted them before.

Based on what information do you 'know' that the cable needs RCD protection? I'm not aware of a regulation which requires RCD protection for SWA?
Installing an isolator and a commando socket you would basically be installing two isolators immediately next to each other. I could almost understand it if you wanted to fit a switch before the socket, but not an isolator.

 

[Pauldicker]

Use an installation method that doesn't require RCD protection and use a unit at the far end with a combined RCD and commando socket.

I'm still fairly new to this so please forgive me. ( everyone needs to start somewhere, lol)
i assumed as it is an outdoor location it would need to be rcd protected, I do not know if swa is exempt from rcd protection, the idea of putting an isolator and rcd commando does seem pointless.
And as it's a new circuit I thought all new circuits needed to be rcd protected and I will be certificating it under part p.

 

[Pauldicker]

What would you suggest leesparkykent, by the way thank you everyone for your input.

 

[davesparks]

I'm still fairly new to this so please forgive me. ( everyone needs to start somewhere, lol)
i assumed as it is an outdoor location it would need to be rcd protected, I do not know if swa is exempt from rcd protection, the idea of putting an isolator and rcd commando does seem pointless.
And as it's a new circuit I thought all new circuits needed to be rcd protected and I will be certificating it under part p.

Are you an electrician? You are asking questions which suggest you don't fully grasp some of the basics.
It is not a case of SWA being exempt from additional protection by RCD, it is a case of additional protection sometimes being required in certain situations. You are very unlikely to need RCD protection for an SWA connected to a TN earthing system.
You cannot 'certificate' (if that is even a word?) under part p, an installation should be certified in accordance with bs7671. Some domestic work should be notified in accordance with part p, but there is no certification attached to this

 

[Leesparkykent]

What would you suggest leesparkykent, by the way thank you everyone for your input.

I wouldn't bother with a commando socket I would put a rotary isolator in. If you can't find an rcbo then you could come out the existing board using an mcb, in to an enclosure with an RCD and run a swa out from the enclosure to the rotary isolator outside.

 

[davesparks]

I wouldn't bother with a commando socket I would put a rotary isolator in. If you can't find an rcbo then you could come out the existing board using an mcb, in to an enclosure with an RCD and run a swa out from the enclosure to the rotary isolator outside.

He's already said the commando socket is required by the hot tub company

 

[Leesparkykent]

He's already said the commando socket is required by the hot tub company

Cool, didn't see that. Then install a commando socket instead of the rotary isolator :smile5:

 

[Leesparkykent]

I appreciate that every one has to start somewhere but as already pointed out this is pretty basic stuff so getting an experienced spark in for you to work along side on the job maybe a better option.

 

[Pauldicker]

I have been asked by a customer to quote for the wiring to a hot tub. I have not done one yet so some advice would be appreciated.

consumer unit is a lewden, i plan on using 6mm 3core swa (max distance 20m) to a weatherproof isolator, then to a female blue commando socket required by the company. Can only find ip44 at present looking for an ip56 as it will be outdoors albeit under a lean too.

so here's the question the company want provided a 16A mcb/rcbo type c,
I cannot seem to find a type c Lewden rcbo , is there a compatible brand?
Am I correct in thinking that the commando socket has to be at least 2.5 m away from tub as per 17th edition for swimming pools. Or more than 2.5 m high?

Anything else I need to consider.

i have aver also calculated the following.
3core swa, Approx 3kw 16a, 25m distance, clipped direct.

That gives me a cable size of 2.5mm with a percentage drop of about 3.4%
correct or go larger?

 

[Pauldicker]

Ok it's an error on my part. I will be notifying the work under part p, it might seem basic to some very experienced people, but I was just after ideas as I've not done a hot tub.

 

[davesparks]

Ok it's an error on my part. I will be notifying the work under part p, it might seem basic to some very experienced people, but I was just after ideas as I've not done a hot tub.

Not having done a hot tub shouldn't affect your knowing when and why an RCD is required!