Xmas light etc and Hot Tubs

[RickH]

I understand requirements for power supply to HotTubs… covered well on:
https://professional-electrician.co...allations-how-to-stay-out-of-hot-water-napit/

What about about garden lights, seeing plenty of pictures of people who have festooned their hot tubs … typically under a pergola or decking roof. Particularly now extra Xmas lights.
This put them often less than 2m horizontally, and 2.5m vertically.

Do the ‘power’ requirement dimensions apply equally to lighting …. typically these are the multi LED strings .. powered by an indoor power supply plug-in transformer.

Or are these considered safe (SELV) … they are designed for outdoor usE, but unsurprisingly they say nothing about use near Hot Tubs.


Apologies if seen as simplistic Q.

 

[ericmark]

The hot tub, EV charging point, and other items used outside the homes equipotential zone presents special problems.

In the main we aim for class II, read this about broken PEN it not as simple as earthing/bonding or not earthing/bonding, selecting what method to use has for many years caused problems, back in 2005 the IET was giving special instructions for outbuildings and things like petrol stations, narrow boats, and caravans have for many years been banned from using a TN-C-S supply.

So what we are looking at is a risk assessment, how likely is it that the water in the hot tub is a different potential to it's surroundings, the same applies to patio heaters, and lights, this case where a 9 year old is killed in a pub does in many ways show the problems.

Two people were involved with the electrics, and it seems reading from the reports uncertain who did what, the fact one also did other things points to him being the one to blame and he went to jail, but all too easy for errors to be made when advising some one, and since the dangers are so high with a hot tube, I would say either do it professionally, or do like my brother-in-law and heat with a wood burning boiler, with no electric anywhere near.

The problem with a broken PEN is you could be electrocuted even when the main isolator is off. And a RCD will not offer any protection as it does not switch the PEN.

 

[SUNRAY]

The problem with a broken PEN is you could be electrocuted even when the main isolator is off. And a RCD will not offer any protection as it does not switch the PEN.

One most certainly can get nasty shocks by placing one across 2 different earth points.

See post #2 in this https://www.diynot.com/diy/threads/a-real-moan-tonight.552183/page-6
And that was with the CU isolator and all MCB's off

 

[ericmark]

I have only found broken PEN on a few times, it is rather rare, just as well as it caused loss of equipment never mind the change of getting a shock, so very likely an electrician could fit 100's of out door hot tubes connected the the TN-C-S earth and not have a problem reported.

The same applies to EV charging points, I am told the one at work has a TT supply, but is within arms length of the building metalwork, so one could touch both earths at the same time, but since the building is connected to 8 mile of railway, it seems highly unlikely even if with did have a broken PEN that there would be much of a voltage rise between the two earths.

On the one time in the UK when I found a PEN had broken, road works not theft, it caused the earth wire from house to radio shack to melt, and all power had been turned off before I got there, so saw the volt meter show the varying voltage, but was some 25 plus years ago so can't remember the reading.

And most hot tubs seem to use wooden frames, so not sure if even in the garden the voltage difference would exceed safe levels?

So more looking at worse case scenario, and I have looked at work where caravans and motor homes of volunteers are parked within a meter of the accommodation building and plugged into a commando socket, which I don't think is TT earthed.

This has been a question raised a few times, if the socket is fitted to use garden equipment, drills, grinders etc. does it really need to be TT? Just because some one has plugged in their motor home, does not mean the socket was fitted with that in mind.

It is only class I equipment which can cause a problem, most hedge cutters and the like, are class II. All I can say is I am not the safety officer.

 

[bernardgreen]

Differences in potential between PEN "Earths" and true Ground should be considered with care.

A gas meter reader wore gloves after getting a shock when he touched a meter.

Where I used to live the village sewage pumping station was on the same supply cable as the 11 houses. The potential difference between the incoming PEN and a ground rod in the banks of the stream was very variable. I didn't record it but did see voltages of more than 10 volts. This was due to phase unbalance and voltage drops along the Neutral in the network,

The situation improved when a new dedicated supply was installed to supply the pumping station.

A cable fault on the supply cable to our part of the village ( phase to Neutral, then open circuit phase ) was "quick fix repaired" by strapping the lost phase to one of the other two phases. This created a large unbalance and hence high currents in the Neutral to the substation causing significant potential differences between PEN "Earth" and true Ground potential.