Another Hot Tub Thread Part 2

[Midwest]

Following on from the last two more technically debated threads:

32A supply for Hot Tub of a PME supply
Another Hot Tub install

I posted a question, in the last one, but didn't get a reply, so starting another one. Hope the Mods don't mind.

So posting my question again, slightly edited.

I’ve been reading lots of threads, about hot tubs & the like, using a PME supply.

I’m thinking of buying one of those inflatable hot tubs Lazy Spa, primarily as a glorified paddling pool for my grandson. I was quite happy to plug into my outdoor socket on my composite (plastic) decking; I have a PME supply.

But since then, I've been reading all sorts things about extending pme (to an outside environment), and I've been contemplating whether to risk it. Manufacturer recommends connecting to equipotential bonding terminal

My options I know, are to either TT just the supply to the tub socket, use my pme supply and try and supplement that with a rod of <20. My sub soil is littered with rocks. Or just use the pme supply without a rod, and don't worry cause its on my plastic decking.

Or just forget it, and keep filling the paddling pool!

Your thoughts?

 

[pc1966]

I’m comfortable with the use of these sockets. Only used for mainly Class 2 stuff by me.

Fair enough. But I would fit a double socket for the hot tub so anyone wanting to plug something else in like a radio, etc, is not tempted to go for one of the PME sockets instead.

 

[bigspark17]

Might it be an idea to put all of them on TT so you don't have to concern yourself about any class 1 stuff plugged in to extension leads, etc, as well?

you cant stop people plugging in extension leads and throwing them in the bath. You cant stop stupidity im affraid! Dont over think it youll go mad otherwise :/

 

[Lister1987]

With regards to Matt:E I (and others) have been pushing them to give an offical line in the sand in the form of a statement on thier website.

 

[marcuswareham]

I’ve got other outdoor sockets on pme. I’ve a plan for services, so shouldn’t be hitting anything hopefully.

Also make sure the Rod is not too close to anything metallic in the ground which would be bonded to the PME MET (gas pipes, etc)

As if you are too close to bonded metal work, the voltage from a PEN fault will appear on the earth rod, and you have situation you are trying to mitigate against
[automerge]1598220309[/automerge]

With regards to Matt:E I (and others) have been pushing them to give an offical line in the sand in the form of a statement on thier website.

View attachment 60354

The single phase Matt:e device is not appropriate to protect a hot tub from PEN conductor faults in my opinion, it gives a false sense of security

It is very possible to have a PEN fault where the voltage between L & N remains within 207v - 253v but the voltage between the PEN and true earth are above 70v, this is due to phase imbalances on the network and also extraneous conductive parts within the installations
[automerge]1598220692[/automerge]

Following on from the last two more technically debated threads:

32A supply for Hot Tub of a PME supply
Another Hot Tub install

I posted a question, in the last one, but didn't get a reply, so starting another one. Hope the Mods don't mind.

So posting my question again, slightly edited.

I’ve been reading lots of threads, about hot tubs & the like, using a PME supply.

I’m thinking of buying one of those inflatable hot tubs Lazy Spa, primarily as a glorified paddling pool for my grandson. I was quite happy to plug into my outdoor socket on my composite (plastic) decking; I have a PME supply.

But since then, I've been reading all sorts things about extending pme (to an outside environment), and I've been contemplating whether to risk it. Manufacturer recommends connecting to equipotential bonding terminal

My options I know, are to either TT just the supply to the tub socket, use my pme supply and try and supplement that with a rod of <20. My sub soil is littered with rocks. Or just use the pme supply without a rod, and don't worry cause its on my plastic decking.

Or just forget it, and keep filling the paddling pool!

Your thoughts?

Following on from the last two more technically debated threads:

32A supply for Hot Tub of a PME supply
Another Hot Tub install

I posted a question, in the last one, but didn't get a reply, so starting another one. Hope the Mods don't mind.

So posting my question again, slightly edited.

I’ve been reading lots of threads, about hot tubs & the like, using a PME supply.

I’m thinking of buying one of those inflatable hot tubs Lazy Spa, primarily as a glorified paddling pool for my grandson. I was quite happy to plug into my outdoor socket on my composite (plastic) decking; I have a PME supply.

But since then, I've been reading all sorts things about extending pme (to an outside environment), and I've been contemplating whether to risk it. Manufacturer recommends connecting to equipotential bonding terminal

My options I know, are to either TT just the supply to the tub socket, use my pme supply and try and supplement that with a rod of <20. My sub soil is littered with rocks. Or just use the pme supply without a rod, and don't worry cause its on my plastic decking.

Or just forget it, and keep filling the paddling pool!

Your thoughts?

In the hot weather I looked at how much those Lay-Z-Spas cost, then realised I am short on money from covid plus space to put the thing!

When i was looking into them although, its appeared to me they are class 2 double insulated, I believe the newer models have a heating element sounded in plastic or something like that. So in that case it doesn't matter what the earthing arrangement is as the device doesn't have a connected CPC for any PEN fault voltage to cause a problem.

 

[Midwest]

Think I mentioned that I watch a John Ward video (posted June 2020) that he has his doubts about the likes of the Matt:e charger, for the reasons given by @marcuswareham. in fact he suggested the only real fix is item ii of that reg, being a large earth mat under drive or bond to reinforcing bars in foundations, something @davesparks might like to hear.

I have a new build, so all the services are in plastic, so no metal pipes about. The only other issue is neighbours car chargers. One neighbour has an ev, but he’s gone for a podpoint, which is one of those rod less chargers.

Re the Class 2 issue, Lay-z-spa says Class 2 on their web page spec, but Class 1 in the manuals (it also states the pump should be ‘grounded’, lift from US instructions I suppose). I’ve emailed them for clarification.

 

[pc1966]

I would go for rod(s) that are fairly close to the hot tub location (within safe and practical fixing, of course), after all the goal is not so much "true Earth" as a low voltage difference to anyone stepping in/out of the tub.

 

[marcuswareham]

I wonder how much a 3kw isolation transformer would cost, possibly more than the hot tub

 

[telectrix]

37 posts discussing how to fi a plug and play hot tub. the mind is flabbergasted, and on reflection, gets flabbered again.

 

[Midwest]

37 posts discussing how to fi a plug and play hot tub. the mind is flabbergasted, and on reflection, gets flabbered again.

The manufacturers instructions say to ‘ground’ the pump. I’d rather spend some time getting opinions, before exposing my grandson to any possible dangers. Course I could just not get one.

 

[Midwest]

Lay-Z-Spa have confirmed that my appliance is Class 1.

 

[nicebutdim]

And yet their website clearly states Class II for that very model. Wonder how many of their customers would go to the lengths that you have in order to verify what they might need to do, prior to installing one of these products that are advertised as 'plug and play'.

Very few I suspect.

 

[pc1966]

Once you get the hot tub you will know for sure - just a continuity meter's probing away.

So ladies and gentlemen, what do we think the time to thread resurrection will be?

 

[Midwest]

Once you get the hot tub you will know for sure - just a continuity meter's probing away.

So ladies and gentlemen, what do we think the time to thread resurrection will be?

I’ll let you know when I’ve put me spike in; won’t be anytime soon though. Mainly because they haven’t any tubs for sale.

 

[partplonker]

If you haven't bought it yet, you could make sure you buy a class 2 tub and save yourself some work? I've got an Mspa inflatable tub, which is both class 2 and has an inline 10mA RCD.

 

[Midwest]

If you haven't bought it yet, you could make sure you buy a class 2 tub and save yourself some work? I've got an Mspa inflatable tub, which is both class 2 and has an inline 10mA RCD.

The manuals I’ve read online, refer to attaching to grounding point etc. No mention of what Class electrical appliance they are? It suggest the pump is 12v.

Yours definitely Class 2.

 

[partplonker]

The manuals I’ve read online, refer to attaching to grounding point etc. No mention of what Class electrical appliance they are? It suggest the pump is 12v.

I'll be honest, I started out thinking this thread was a bit daft, but you're right. I'm not sure where I got the class 2 from because I've just looked and I can't find a double insulated logo on the unit or any mention of device class in the manual. It does state that the filter/pump is 12V and the heater/jets are mains voltage and their peak demand but that's about it.

The manual states "This appliance must be connected to a grounded mains supply socket and a supply cord fitting with a plug and PRCD equipped with a tripping current of 10mA. The appliance with earthing must only be plugged directly into an earthed socket-outlet of the fixed wiring."

Ok, so far so good.

It then says "A qualified electrician shall wire the spa control unit to the household equipotential terminal using a minimum 1.5mm2 solid copper conductor".

I wonder if this is really aimed at other countries where sockets without an earth are still a possibility?

I can't really see your average consumer buying one of these and being expected to crack open the tub electrics, whip out some singles and lugs and start bonding things, so I have no idea what they're on about.

Interesting that they state a minimum CSA for the earth conductor though. I'm pretty sure there are still older installations around that used 2.5mm2 T+E with a 1mm2 earth.

Thankfully, I have a TN-S supply so I'll not give it any further thought and enjoy my hot tub!

 

[Midwest]

I'll be honest, I started out thinking this thread was a bit daft, but you're right. I'm not sure where I got the class 2 from because I've just looked and I can't find a double insulated logo on the unit or any mention of device class in the manual. It does state that the filter/pump is 12V and the heater/jets are mains voltage and their peak demand but that's about it.

The manual states "This appliance must be connected to a grounded mains supply socket and a supply cord fitting with a plug and PRCD equipped with a tripping current of 10mA. The appliance with earthing must only be plugged directly into an earthed socket-outlet of the fixed wiring."

Ok, so far so good.

It then says "A qualified electrician shall wire the spa control unit to the household equipotential terminal using a minimum 1.5mm2 solid copper conductor".

I wonder if this is really aimed at other countries where sockets without an earth are still a possibility?

I can't really see your average consumer buying one of these and being expected to crack open the tub electrics, whip out some singles and lugs and start bonding things, so I have no idea what they're on about.

Interesting that they state a minimum CSA for the earth conductor though. I'm pretty sure there are still older installations around that used 2.5mm2 T+E with a 1mm2 earth.

Thankfully, I have a TN-S supply so I'll not give it any further thought and enjoy my hot tub!

Bear in mind these products were originally designed for US market, so they would be adapted for European markets accordingly. The manuals are probably just a cut paste from the US ones, with certain bits changed, like the voltage etc. Thats why I think, words like grounding are used. The Lay-z-Spa instructions, suggest a 2.5mm solid conductor.

On your last point, you may wish to reconsider your TN-S supply. From what I heard and read, most TN-S supplies would of had repairs carried out on the DNO cables, at some point. Any such repairs would convert it to TN-C-S. If you have what you think is TN-S, you should treat as TN-C-S.

 

[telectrix]

with these modern hot tubs, you are more in danger of being clouted round yer 'ed with a frozen turd dropped from a 747 @ 37,000ft.

 

[partplonker]

On your last point, you may wish to reconsider your TN-S supply. From what I heard and read, most TN-S supplies would of had repairs carried out on the DNO cables, at some point. Any such repairs would convert it to TN-C-S. If you have what you think is TN-S, you should treat as TN-C-S.

I heard about that and I think that happened in the previous house I lived, where the supply was a 1960s lead sheathed cable.

I currently live in a flat in a converted former hospital/mental asylum/country house. We have our own 11kV transformer and all the feeds to our flats or communal areas are mostly in MICC with some SWA for later additions. Earth is separate from neutral all the way back to the transformer. It's quite an interesting setup because the DNO are only responsible for the transformer. All the LV switchgear and cabling is our responsibility (the tenants) to maintain. But I digress ...

 

[pc1966]

with these modern hot tubs, you are more in danger of being clouted round yer 'ed with a frozen turd dropped from a 747 @ 37,000ft.

Or a stray 737 MAX...

 

[Midwest]

with these modern hot tubs, you are more in danger of being clouted round yer 'ed with a frozen turd dropped from a 747 @ 37,000ft.

That won’t happen. I live near Brize, so all the military planes keep them away and the store aways away.