Shower Electric shocks but not everyone

R

Roger

Got a call today to go to a old flat as the lady was getting shocks when she was having a shower.
She explained that when she touches the tap and then the shower unit she gets a tingle and now here daughter is getting them as well.
Considering the property is a rental I was amazed to see a old rewireable fuse with some retrofit Wylex MCB put in there.No RCD ,bit of old twisted uninsulated earth wire coming up from the supply cable buried in the wall.The fuse box was not a stand alone type unit it was integral in a metal type service cabinet about 2 foot tall.
The property has an earth 0.6 (TN-S) however it only goes to power circuits,the lights have no earth and the circuit feeding the shower pump.Pulling of a cover in the cabinet revealed about 3 cables out of 8 actually had a cpc in them.
Incoming water is bonded ,but not gas to this flat and next door.Wondering around my R2 Long lead could get no continuity on any taps ,shower.
There is no supplementary bonding anywhere,lots of plastic unions so continuity if it was there is now broken.
The shower has a pump and the boiler is a conventional type with a hot cylinder upstairs.No bonding in the airing cupboard.
Now I assume she is experiencing a difference in potential which is why she is getting shocks.I could not get any shocks with the shower running and checked for any voltage present just with my volt stick and direct measurement,non existed.

But why does she get it and the previous tenant did not ?

Apart from saying the flat should really be rewired and it is not really suitable for renting i need to provide a detailed explanation as to what is going on and why it has not happened previously.

If i upgraded and put in main bonding to services and run upstairs to bathroom from MET,also supplementary bonding in bathroom under bath and sink and airing cupboard would that fix it.

She has just signed for 6 months so not really practical to rewire now,if he actually wants to go ahead.
Any help greatly received
 
I wouldn't suggest he does his testing wet :p

You mean you don't carry your speedos in your tool kit :p

I doubt you'd get a resistance that low, but agreed that could in theory be a worse case.
If the lady is wet and standing in the bath not unusual for body resistance to fall to 1000 Ω (even wiki says so)

Following that logic though the voltage you could be looking for could be as high as 230-2=228V to get a PD of 2V. Depending on what the potential is between.
:confused: a voltage is the difference in potential between two points. Yes if you are in contact between 2 points at 300V and 228V you feel the effects of a 2V potential difference - but the moment one hand touches something approaching earth potential you are going to feel a lot more lol :)
 
you have said the install looks old i would insist that the installation be given a periodic , i had a call once infact the call i had i has been used on several articles one in wiring matters and was an old install rented property , what basically happened i got a call getting shocks of off metal work in the house , went there thinking static , only to find a woman in her dressing gown sat on the floor shaking her kids crying ,quite stressfull to see ,asking what had happend the lady had started to run a bath , during the time the fault had occoured the bath had filled with very hot water due to a faulty tank stat to when she went to get in the bath she felt a tingle and though it was just because the tap was hot , it wasnt untill she put her leg into the bath that and ended across the bathroom she realised it was live switching off the power and carrying out some tests i discovered a fault in the immersion heater 3036 rewireable fuses , the insulation had broken down on the cable causing a short between live and earth , but instead of blowing the fuse the live blew the earth connection and welded its self to the metal work of the heater this caused every part of the water system had become live cast iron bath was live even the flush handle of the toilet was live , although the bonding had been installed it had never been connected if it had it would have blown the fuse the lady was very lucky , i made the install safe and next day carried out a periodic inspection , what you have here may not be anything like what i discovered and the woman too but you cant be to sure , so inspect the shower and recommend a PIR at the end of the day doesnt matter who they are the land lords have a duty of care , print off the ESC 's landlord guide to electricicty and give it to them but make sure you test the shower top to bottom and check the bonding some thing so simple could save a life
 
"I wouldn't suggest he does his testing wet" :p

I'll take me towel !

I did advise her not to use the bath and shower until it is rectified,got 2 kids in there as well.Like you say i touched it last.
The whole place is really shabby and very old.God only knows what else is on the shower circuit and where it is taken from.I''ll give him a day rate and go from there.She's paid 6 months up front so the landlords feeling a bit flush.
Just hope the earthing and bonding solves it.
I ask what he has done about the periodic,I know he has had the gas checked as that bloke recommended me.Either way i will put it in writing so me bum is covered.
Cheers
 
:confused: a voltage is the difference in potential between two points. Yes if you are in contact between 2 points at 300V and 228V you feel the effects of a 2V potential difference - but the moment one hand touches something approaching earth potential you are going to feel a lot more lol :)

Agreed. Think I'd best pack some for future use ;)

So we need options ... how else can we be getting around 2V between a tap and shower head?

Any potentially faulty SELV in the bathroom?
 
Just a thought Roger, we are talking about the bath tap and shower head over the bath here?

Yes the bath tap is at the side and then you have a shower valve in the wall with a head above the bath.We have a shaver point and the lighting is just a ceiling pendant,not really suitable.The lighting circuit has no earth.
 
That is why the PIR is really the way to go - Get the continuities and IRs checked and find all the picture frames that, over the years, have been hung by nailing between the N and cpc :eek:

That was almost my first question as she has just moved in and obviously will be putting the old pictures up and making it homely.
Been there before !
 
Must admit I'm leaning towards a full PIR, as this is a flat though it may be that you're getting an earth potential from elsewhere in the building (just to add to the fun).

Might be an interesting exercise to take some resistance readings between each of those 3 points.
 
That was almost my first question as she has just moved in and obviously will be putting the old pictures up and making it homely.
Been there before !

Me too ! Not just seeing the effects -I even swung the hammer myself when the missus says "not there a little more to the left" :o
 
Re reading this quickly you say that the pump only feeds the shower so there is a pssibility that the differential is between the tap feeds and the shower pipes so I would bond across the pump. As there is no main bond to the gas there is a possibility of an earth leakage on the boiler which is finding its way to the water pipes and the shower pipes being buried in the wall could be getting an earth potential frm a damp wall.

Or am I talking crap?
 
Oh no ,you had me convinced that you knew what you were talking about.After posting it on here at least it gives me a bit more confidence to go down the right route.

Thanks for all the input ,great forum.

Whats the going rate for a PIR about £125-£150 ?

I'll get me shower bag and off i'll go although got a faulty fire alarm to sort out first.

Thanks again
 

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