On Monday, 24 April 2017 08:20:05 UTC+1, Brian Reay wrote:
On 24/04/2017 06:53, F Murtz wrote:
tabbypurr wrote:
On Sunday, 23 April 2017 09:21:57 UTC+1, F Murtz wrote:


I have a strange situation in my bathroom, all the copper water pipes
are bonded to earth externally but I sometimes get a tingle to taps when
standing in the shower, (About 5 volts measured from metal round drain
to taps)
I can only assume that when the house was built(on concrete slab) the
reo steel in the concrete was not bonded to earth which is a requirement
today

You need to fix that.


NT

I can not be bothered at the moment am not the slightest bit worried
that it is ever going to electrocute anyone, Some day I may jackhammer a
bit of concrete to expose some reo and bond it,


The 5V isn't but it is a sign of something more serious- it looks like
you may have a PME earth and have 'imported' an external (real) earth.

PME earths are fine but rely on your not 'mixing' a PME earth and a real
earth in case there is a earth neutral fault- specifically a break in
the combined Neutral and Earth conductor which supplies your property.

It is indeed a hazard. A nearby strike would also put a massive voltage gradient across anyone in the shower.


NT