Water heater Siemens mild eletrical shock

[kyrre]

I have several water heaters from Siemens.

DH06111

DH12103

After i put proper grounding in the house i get mild electrical current from them.

I have measured the heater with ohmmeter.

Element to element 18ohm. 3kw (Same for both element when disconnected)

Element to earth sho ~35Mohm

I have a copper ground spear and the ground spear the PEA use.(x shaped galvanizes steel connected to 10 mm2 cable)

The electrical current is passing through in water.

If i stay on dry tiles -> no mild shock.

If i stay on wet floor - mild tickeling where i have small wounds. even if i touch the kitchen sink or in the water stream. or the shower hose, taps.

1. Can it be some earth differential due to scaling?
Can earthing of house structure even out this?

2. Is a 500v insulation test the nest step? (I did this when installing the earth with acceptable values accordingly)

Thanks for any answers

[T_Dog]

Yikes! First of all, disconnect the breakers and don't use it. I doubt your grounding system is connected properly, or you have a fault where current is entering your ground system. You should not get a tingle at all from a hot water system if it is connected to a ground pin as you describe, and IF there are no faults in the surrounding electrical connections.

edit: How old are the heaters? Is it possible the heating element has corroded through?

Edited September 4, 2014 by T_Dog

[Crossy]

If you are only feeling a tickle where your skin is broken it must be a very mild shock.

It's quite possible to get a potential between spike ground and 'real' ground (the re-bar in your floor). The solution is to connect your ground spike to the house metalwork and create an equipotential zone covering the whole building.

But before you do that;-

Are your heaters all connected to the same ground spike which is also connected inside your distribution board?

Can you upload a photo of the inside of your distribution board so we can see how the incomer is wired?

Do you have an RCD or Safe-T-Cut device?

[kyrre]

If you are only feeling a tickle where your skin is broken it must be a very mild shock.

It's quite possible to get a potential between spike ground and 'real' ground (the re-bar in your floor). The solution is to connect your ground spike to the house metalwork and create an equipotential zone covering the whole building.

But before you do that;-

Are your heaters all connected to the same ground spike which is also connected inside your distribution board?

Can you upload a photo of the inside of your distribution board so we can see how the incomer is wired?

Do you have an RCD or Safe-T-Cut device?

Hi,

I will try to connect the house structure to the main earth to see if it clears the mild shock.

At least one heater is connected to the ground bar as its on the attic and i have connected it myself. The kitchen one i am not sure as its only a wire coming from the wall. It might be just put in the ground outside.. I will install a new grounding from proper ground and see if it helps.

The distribution board i don't want to show a picture off at current state as its under work. As i am about to change all old breakers and put in new ones with RCD.

It have neutral bar, Earth bar and no MEN link.

Thanks for good answers as always Crossy.

[kyrre]

Just a informal update on the problem...

I connected the house structure to the main earth and the mild shock disapared totally.

So eight er there is a earth differential or an earth leek in the neighborhood.

[Forkinhades]

If your installation was to the current PEA standard, then you would not get shocks.

All info in the pinned threads.

Just to summerise, front end RCD (Safety-Cut ), with adequate earth rod, and MEN connection.

[Crossy]

I agree Forky, with one rider "and the local distribution system is to the latest standards".

Neither of us like the haphazard way that PEA are implementing MEN. It's quite possible that our OP has the only MEN connection in the village that has previously been TT, coupled with a crumby rod and high neutral current his 'earthed' equipment could get quite a few volts above real ground (he was complaining about shocks only on broken skin so the voltage must have been really small).

That's why I suggested making the whole building into an equipotential zone by connecting the building steel to the ground rod (that would improve the ground resistance too by the Ufer effect).

Seems to have had the desired result