sunday shock scenario

Karin · Sep 25, 2016

ok so this is a scenario that i read on another forum that interested me. the solution wasn't mentioned.

shock received from shower tap while standing wet feet on tiled floor.
testing from the tap (PME earth via bonding) to a screwdriver in the garden (true earth) showed a potential difference of a few volts. clearly not a huge amount but enough for a discomfortable tingle in the situation.
bathroom floor then verified to be at true earth potential (so essentially not part of equipotential zone)

just curious as to what you guys would do?

sup a can of 'man up' and deal with it? chuck some plastic mats in the bathroom? rip up the floor and start again? TT the house?

Richard Burns · Sep 25, 2016

Why is the floor of the shower at true earth potential?
Anyway, install a low resistance earth rod to the MET so that the MET is closer to true earth potential and the PD at the shower is not so great.

Marvo · Sep 27, 2016

You'd need to establish if it's the taps that are at an elevated potential or if it's the shower floor. I'd test the earth impedance of the incoming supply and if it's good then run a fly lead from the main earth terminal to the shower as an earth reference for testing. These types of fault can be time consuming to find and repair.

Shocks from Bath tap - http://www.electriciansforums.co.uk/threads/shocks-from-bath-tap.70467/#post-688922

Karin · Sep 27, 2016

presumably ground floor bathroom on some kinda clay tiles, maybe rural/farmhouse scenario.

ok cool, i had read about additional local electrodes on PME, though at the time i'd read that they are no longer installed as routine as (amongst other reasons) you'd really need a fantastically low Ra to have any real effect on reducing touch voltages. so it's taken me a while to write this as i've gone back and forth and read a whole load of stuff on the topic! i notice you've specifically written low resistance earth rod, presumably it'd have to be pretty low Ra to compete with the PME earth impedance and drag the MET down closer to local earth?

i hope i'm reading this right!