Shocking discovery.

[SUNRAY]

Had a nice experience earlier today... Not.
Hotel swimming pool had to be closed off due to filter plant failure.
The power was isolated while some leaking pipes were replaced but it would not restart on power-up.
The big clue was the shock I got off the contactor enclosure when I pushed the green button. At some time in the past the 400v coil contactor (still laying on the floor) had been replaced with a 230v version and as there was no neutral in the pump circuit it was connected to earth instead. As the metal pipes had been replaced with plastic there was now no earth either.
The 3phase supply was a 3core flex with those long established phase colours of: black, blue & yellow!

 

[securespark]

Jesus H Christ.

Condemn!!!

 

[Mikefromlondon]

shocking !

 

[stillp]

A hotel swimming pool, of all places to have an unsafe electrical installation!

 

[SUNRAY]

shocking !

Oh yes it was shocking but no one else had experienced it

Jesus H Christ.

Condemn!!!

I was testing with a view to repairing, not condemming.

A hotel swimming pool, of all places to have an unsafe electrical installation!

They are in the process of adding some facilities to the hotel and generally updating for which the water supply to the plant room had to be isolated and re-routed, hence repairing the leaks while it was off.
There was a lovely offcut of 5core armoured there and scrubbing around in the extention found enough bits of ss and brass glands and locknuts to make a grand repair between the wall mounted isolator and pump.

This was an overnight job by their own maintenance guys, they actually replaced all of the steel pipework (30ish m) and fully expected it to work afterwards. The rest of the pool plant is only 2 years old and controlled by telemeq plc in a panel.
I checked earth resistance to all of the electrical parts and everthing else is OK as observed by their maintenance guys.

 

[stillp]

the 400v coil contactor

So there's 400V on the Start pushbutton? In a wet area?

 

[SUNRAY]

So there's 400V on the Start pushbutton? In a wet area?

And this is rare?

 

[ericmark]

So there's 400V on the Start pushbutton? In a wet area?

Would not have thought so, maybe 400 volt phase to phase, but only 230 volt phase to earth. Also current limited to what coil will pass, but could be some back EMF which could exceed 400 volt.

Some one was clearly at fault, and it would seem they knew what they were doing, as to if one could trace who did it is something else, clearly had some one died as a result then there would be a full investigation, but the expense of finding the guy likely means he will get away with it.

I expect if it is reported, i.e. Sunray has gone to hospital for a check-up, they have to then report it, the HSE may be involved, but I would guess Sunray like I have done many times, had some expletives, but did nothing else.

However good reported on here, as it may make us more aware, and get the neon screwdriver out again?

 

[stillp]

Would not have thought so, maybe 400 volt phase to phase, but only 230 volt phase to earth.

I would have expected the pushbutton to be in series with the coil. What does the current have to do with it?

 

[ericmark]

If we consider earth used instead of neutral any current going to the earth must go through the coil with the earth disconnected that current must go through the coil, and the person, and something which is in contact with the person and so to earth. It is therefore going to be less than the total voltage across the person and the total voltage can only be 230 volt RMS.

We are allowed some earth leakage, not got the regs with me, but seem to remember around 5 mA, so 230/0.005 = 46 kΩ now we don't know what the resistance would be of the coil, but it is highly unlikely that some one getting a shock would get even a full 230 volt never mind 400 volt.

However it is still wrong, and unless people who do things like this are caught and brought to task, then it will continue to happen, every time I completed a minor works or installation certificate I was well aware so time in the future some one could be taking me to task, but with repairs it was common not to log all repairs specially when busy, if the repair is not logged it would be near impossible to find who did it.

However hotels does not normally have a in house electrician, so there is a chance that some one has invoiced for the work. As to if it is worth the effort is another thing, if there was loss by the hotel due to the pool failure maybe, but likely the guy will get away with it.

 

[stillp]

If there is 400V supplied to the coil when the start button is closed, but the other end of the coil is disconnected, then a person could be in contact with the 400V from the pushbutton, and also in contact with earth.
In some countries (e.g. the US) it is illegal to use 400V coils in manually-operated motor starters.

 

[SUNRAY]

If we consider earth used instead of neutral any current going to the earth must go through the coil with the earth disconnected that current must go through the coil, and the person, and something which is in contact with the person and so to earth. It is therefore going to be less than the total voltage across the person and the total voltage can only be 230 volt RMS.

We are allowed some earth leakage, not got the regs with me, but seem to remember around 5 mA, so 230/0.005 = 46 kΩ now we don't know what the resistance would be of the coil, but it is highly unlikely that some one getting a shock would get even a full 230 volt never mind 400 volt.

However it is still wrong, and unless people who do things like this are caught and brought to task, then it will continue to happen, every time I completed a minor works or installation certificate I was well aware so time in the future some one could be taking me to task, but with repairs it was common not to log all repairs specially when busy, if the repair is not logged it would be near impossible to find who did it.

However hotels does not normally have a in house electrician, so there is a chance that some one has invoiced for the work. As to if it is worth the effort is another thing, if there was loss by the hotel due to the pool failure maybe, but likely the guy will get away with it.

Yes of course the maximum voltage to earth is 230 nominal even though it was originally a 400 coil across 2 phases. The average resistance of a human body is in the order of MΩ's and my guess is the coil resistance of 10KΩ so the real voltage across the body is 100:1 of 230 = 227.7v minimum at best, in reality it will be more like 500:1. So yes it really is full mains voltage but limited to 23mA (at my guess of resistance).
In this case I was standing on some nominally dry wooden duck boards so the voltage across me was nowhere near 230 but it still b!@@θy hurt and yes there were some other simarly spelt words used to describe the experience. Maintenance guy reckons it hadn't been changed in the 5 years he's worked there so the chances are it will not be investigated further.

BTW, The shape of the 'earth' wire indicates if was obviousely on ph2 originally.

 

[SUNRAY]

If there is 400V supplied to the coil when the start button is closed, but the other end of the coil is disconnected, then a person could be in contact with the 400V from the pushbutton, and also in contact with earth.
In some countries (e.g. the US) it is illegal to use 400V coils in manually-operated motor starters.

The 400v phase voltage is still only 230v relative to earth. In UK 400v coils are very common as most 3ph motors don't require a neutral connexion.

 

[ericmark]

If there is 400V supplied to the coil when the start button is closed, but the other end of the coil is disconnected, then a person could be in contact with the 400V from the pushbutton, and also in contact with earth.
In some countries (e.g. the US) it is illegal to use 400V coils in manually-operated motor starters.

USA has some really odd systems, including DC, one of their systems uses delta wound secondary with one winding centre tapped and earthed, so with a three phase supply you have two phases quite low to earth but third is much higher.

I worked on a Robin tunnel boring machine in Hong Kong which was made in USA, 10,000 volt to machine, transformed to 660 volt three phase quite common with mines and quarries, for main motors then a delta secondary 220 volt phase to phase with an IT earth system. It was a nightmare, everyone had neon screwdrivers, you tested every bit of metal before touching it.

Fault finding was an art, you had to find another phase to compare readings to, earth could be anything. Just glad I did most of my work in the UK which is relatively safe, having also worked with Algerian and Dutch I realise how good the UK system is.

 

[SUNRAY]

I guess I need to clarify this thread and apologise for not putting it into 'outside UK'.
I was actually on holiday in Spain and my granddaughters, along with 500 other guests, were complaining bitterly that the pools were out of bounds and it was starting to look ugly.
We had already established a good relationship with the entertainment staff as this was our 6th visit and a little chat with them soon got to the bottom of the reason. The electricians had been called but would not be in attendance until Monday, Saturday was hot and my offer to take a quick look was received enthusiastically. There was an excellent tool kit available including an unexpected amount of test kit and all in calibration. It took me less than an hour to get running and a further 2 hours to stabilise the dosing.
The hotel refunded the all in part of the holiday (1400 Euro) but I was surprised how many strangers became aware of the situation and tried to buy drinks, I reckon 50 is not an exaggeration.