UK Static/Tingle from shower/towel rad.

[Dunc88]

Hi, working in a property a couple of years old. Earthing System is a TN-C-S.
Customer’s daughter/wife have both complained about receiving a “slight tingle/static sensation” when using the shower in only one of the bathrooms (when touching the shower/or towel rad). I’ve checked the incoming water main & its plastic, so there’s no 10mm water bond. All circuits are protected by 30mA rcbo’s, nothing has tripped to date. Ive only taken a quick look (an hour on the way home yesterday) so running the shower (fed directly from boiler) & turning the rads on whilst checking it with my volt stick is as far as i’ve got, didnt feel anything myself but want to go back again today to have another look. Any advice appreciated.

 

[Pete999]

Hi, working in a property a couple of years old. Earthing System is a TN-C-S.
Customer’s daughter/wife have both complained about receiving a “slight tingle/static sensation” when using the shower in only one of the bathrooms (when touching the shower/or towel rad). I’ve checked the incoming water main & its plastic, so there’s no 10mm water bond. All circuits are protected by 30mA rcbo’s, nothing has tripped to date. Ive only taken a quick look (an hour on the way home yesterday) so running the shower (fed directly from boiler) & turning the rads on whilst checking it with my volt stick is as far as i’ve got, didnt feel anything myself but want to go back again today to have another look. Any advice appreciated.

Yes don't use a voltstick for testing.

 

[snowhead]

The Tingling will be less than 30ma, but a voltage will be measurable between whatever it is they are touching.
Untill it's resolved it would be advisable not to use the shower in question.

YOU probably won't feel it with shoes/socks and dry feet.

 

[Dunc88]

The Tingling will be less than 30ma, but a voltage will be measurable between whatever it is they are touching.
Untill it's resolved it would be advisable not to use the shower in question.

YOU probably won't feel it with shoes/socks and dry feet.

Thanks snowhead, would you recommend testing all circuits in & around the bathroom in question? Not really sure where to start with the next step to be honest as this is a first for me!

 

[telectrix]

firsttest the shower water pipes. seeif they are extraneous ( <22K Ohms to MET ).

 

[Dabbers]

You say that the shower is fed directly from the boiler so the rads will be as well so they should be at the same potential unless the however the water is plumbed in plastic and the rads in copper for arguments sake so I would check the boiler first for any issues and see if you can ascertain what the water and heating is plumbed in ie copper or plastic you will see copper tails and copper pipes at the boiler use a multi meter to find out how much voltage the is between the shower and rad

 

[HappyHippyDad]

Thanks snowhead, would you recommend testing all circuits in & around the bathroom in question? Not really sure where to start with the next step to be honest as this is a first for me!

I'm glad I have not come across a problem like this before as I agree Snowhead it is confusing!
Are the customers getting a shock when they are just touching the towel radiator (without touching anything else, i.e just there feet on the ground) or when touching the towel radiator AND touching part of the shower? Is the shower definitely plumbed and not electric?
Is the towel radiator electric? If so, test the IR of it to line and neutral.
I would also test for voltage between shower and towel radiator. I would also be checking to make sure the house is correctly earthed and do a global IR test.
Does the towel radiator or shower test as extraneous?

Lots of other things keep springing to mind...

 

[Dunc88]

firsttest the shower water pipes. seeif they are extraneous ( <22K Ohms to MET ).

Thanks Telectrix, i’m going over after work so will carry out an R2 test & see what reading I get!
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You say that the shower is fed directly from the boiler so the rads will be as well so they should be at the same potential unless the however the water is plumbed in plastic and the rads in copper for arguments sake so I would check the boiler first for any issues and see if you can ascertain what the water and heating is plumbed in ie copper or plastic you will see copper tails and copper pipes at the boiler use a multi meter to find out how much voltage the is between the shower and rad

Thanks for the reply Dabbers, yes all in copper, I did test between the rad/shower with my voltage tester & all I got was continuity... hope this helps?
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I'm glad I have not come across a problem like this before as I agree Snowhead it is confusing!
Are the customers getting a shock when they are just touching the towel radiator (without touching anything else, i.e just there feet on the ground) or when touching the towel radiator AND touching part of the shower? Is the shower definitely plumbed and not electric?
Is the towel radiator electric? If so, test the IR of it to line and neutral.
I would also test for voltage between shower and towel radiator. I would also be checking to make sure the house is correctly earthed and do a global IR test.
Does the towel radiator or shower test as extraneous?

Lots of other things keep springing to mind...

Very confusing...
Yes when they touch either the towel rad, or the shower. Shower is definitely plumbed & not electric, there is electric underfloor heating which I forgot to mention?
Towel rad also plumbed.
Will test for extraneous later on. Will keep you posted, appreciate your feedback

 

[Lucien Nunes]

Three possible scenarios with different troubleshooting approaches.

A) Full mains voltage through high impedance, i.e. leakage of some sort, with all CPCs intact. This should be detectable by low IR on the leaky circuit / heating element. It approximates to a constant current, maybe in the sub 1mA range. The actual voltage will be unstable and not in itself informative. Remember that a 230V source limited to 0.001mA will not give you a tingle but will read nearly 230V on a high-impedance meter. (I dislike the term 'ghost voltage'!)

B) Normal leakage levels including capacitive leakage of cables, finding its way to extraneous metal because CPC(s) open-circuit. This would be picked up by earth.continuity and Zs tests.

C) Low voltage through low impedance, e.g. difference between local true earth from extraneous conductor and TN-C-S earth from CPC, due to lack of bonding. This approximates to a constant voltage and may vary with installation load. Traceable by the voltage itself and maybe low-range ohmmeter.

 

[Dunc88]

Great, really appreciate the reply! I’ll try and digest it all & make a start after work today! Will keep you posted!

Three possible scenarios with different troubleshooting approaches.

A) Full mains voltage through high impedance, i.e. leakage of some sort, with all CPCs intact. This should be detectable by low IR on the leaky circuit / heating element. It approximates to a constant current, maybe in the sub 1mA range. The actual voltage will be unstable and not in itself informative. Remember that a 230V source limited to 0.001mA will not give you a tingle but will read nearly 230V on a high-impedance meter. (I dislike the term 'ghost voltage'!)

B) Normal leakage levels including capacitive leakage of cables, finding its way to extraneous metal because CPC(s) open-circuit. This would be picked up by earth.continuity and Zs tests.

C) Low voltage through low impedance, e.g. difference between local true earth from extraneous conductor and TN-C-S earth from CPC, due to lack of bonding. This approximates to a constant voltage and may vary with installation load. Traceable by the voltage itself and maybe low-range ohmmeter.

 

[Dabbers]

I know that you have already checked that the Gas or Oil is bonded?

 

[Dunc88]

I know that you have already checked that the Gas or Oil is bonded?

There isnt any, both enter the property in plastic

 

[snowhead]

You also need to know the exact conditions when it's noticed.

For example it could be a nail or screw in the floor that's just into the live of a T&E.
If the floor is then covered in water from the shower and is getting through the floor covering to the nail / screw and someone stands in the water also touching towel earthed towel rail or shower they risk getting a shock.

 

[DPG]

Might be worth getting them to switch the underfloor heating off for a couple of days and see if they notice any difference. In addition to the testing mentioned above obviously

 

[Marvo]

I've fault-found a problem many years ago where there was tingling in a shower. After numerous visits and probably around 14 site hours investigating it turned out to be the drain which was broken under ground outside and a leaking garden light connection box next to it. When the outside lights switched on every evening the drain on the floor of the shower itself was elevating in voltage sufficiently to give someone a nasty tingle when they touched the taps.