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I do seem to getem!

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Piratepete

Hoping to get sensible suggestions for this.

Family in semi-detached house are getting 'tingles' from the basin taps in their bathroom. They're the sensible sort so I have no reason to doubt them. Hubby is technical. He says they've only noticed it recently. But it also happens with the consumer unit turned off!

I've been in and could find nothing wrong. Did bonding tests on pipework and the bath (metal), insulation tests at the CU. All seems fine. Western Power guys had a look, changed the cutout (old one probably 60 years old). The floor is lino (very high IR to earth)

This is an extract of their latest email about the problem.

>'Update on the bathroom problem:

With regard to the odd bathroom problem; it still happens, intermittently, and is definitely apparent when in the bath - despite your measurements showing decent continuity between the two. I can’t explain it, but it is definitely not in my head!! Via a cheapo multimeter I think I’ve ascertained the following...


  • It measures about 1.5V AC between bath water or wet floor and taps/radiator
  • If measured on DC setting, it shows about 0.8V with positive polarity on the water end
  • It is present even if our consumer unit is isolated from the supply
  • The duty cycle setting on the meter shows 50Hz
Could it be something dodgy in the neighbouring property, coming through the ground/drainage? I don’t understand it and can’t explain it - but it’s there. Sometimes.
Is it worth adding some additional bonding between the bath an the pipework, or at least retesting the impedance between the two? I don’t want to worry about nothing, but with a small child and pregnant wife it’s bugging me still.'<

So guys, what should I do next. Nothing rude please!
 
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What type of supply is it? How old is the installation? EEBAD?
If I was in your position I would carry out a full PI of the property and fully document my observations,etc.
Hopefully the problem(s) will be discovered.
You need to be very methodical, don't be tempted to go off on a tangent checking randomly as the fault could be down to a multitude.
Start at the source, earthing and bonding, working your way through the installation and don't leave the property until it is sorted.
 
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Via a cheapo multimeter I think I’ve ascertained the following...



  • It measures about 1.5V AC between bath water or wet floor and taps/radiator
  • If measured on DC setting, it shows about 0.8V with positive polarity on the water end
  • It is present even if our consumer unit is isolated from the supply
  • The duty cycle setting on the meter shows 50Hz
Click to expand...


I'd completely ignore that for starters!
 
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OP Here.
Tingley Taps link very interesting. Details of my problem below.
House is a 30s semi in a village street. Supply is underground TN-S, new (yesterday) 100 amp cutout.
Zs at CU 0.16, PFC 1.45 kA, Earthing in 16mm, Bonding 10mm. CU 16th Ed.
IR All circuits L+N/E 1.44 MOhm.( It's the downstairs ring cct bringing it down but boiler has no proper isolator (unswitched FCU) and couldn't disconnect the fridges). But it passes and is not relevant!

With CU off, current through main earth is 0.4mA DC, 2.6mA AC
With CU on, current through main earth is 0.4mA DC, 5.0mA AC

The bath taps are effectively (measured) well bonded but between the metal plughole and the taps the resistance is 960 Ohms. The voltage between the plughole and the taps is 0.47 VDC and 0.51 VAC. Ohms law gives you 0.48 mA DC which ties up nicely with the current I measured on the main earth.
The client's testmeter (which cost a bit more than £5) gives the same readings.
He says that the voltage rises to 1.5 VAC and 0.8 VDC when they get the tingles (with the CU off).

Can't see under the bath due to the side panel being (permanent) but the bath waste coming through the wall is in lead, no doubt all the way to the trap!

I'll be having a word with Western Power Distribution in the morning!

Cheers
Pete
 
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Piratepete said:
OP Here.
Tingley Taps link very interesting. Details of my problem below.
House is a 30s semi in a village street. Supply is underground TN-S, new (yesterday) 100 amp cutout.
Zs at CU 0.16, PFC 1.45 kA, Earthing in 16mm, Bonding 10mm. CU 16th Ed.
IR All circuits L+N/E 1.44 MOhm.( It's the downstairs ring cct bringing it down but boiler has no proper isolator (unswitched FCU) and couldn't disconnect the fridges). But it passes and is not relevant!

With CU off, current through main earth is 0.4mA DC, 2.6mA AC
With CU on, current through main earth is 0.4mA DC, 5.0mA AC

The bath taps are effectively (measured) well bonded but between the metal plughole and the taps the resistance is 960 Ohms. The voltage between the plughole and the taps is 0.47 VDC and 0.51 VAC. Ohms law gives you 0.48 mA DC which ties up nicely with the current I measured on the main earth.
The client's testmeter (which cost a bit more than £5) gives the same readings.
He says that the voltage rises to 1.5 VAC and 0.8 VDC when they get the tingles (with the CU off).

Can't see under the bath due to the side panel being (permanent) but the bath waste coming through the wall is in lead, no doubt all the way to the trap!

I'll be having a word with Western Power Distribution in the morning!

Cheers
Pete
Click to expand...
couldnt you bond the waste outside then so its all bonded as a tempory measure.

that way there will be no potential between all the metal work
 
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So you have an unbounded extraneous conductive part in close proximity to bonded metalwork.
Might I suggest installing main bonding to the extraneous conductive part sometime soon?

When you measured the current in the earthing conductor how did you manage to measure AC and DC seperately?
What were you looking for when you measured this current?
 
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Had same problem but with a sink in a hall cloak rooms, it could be the PD from the metal bath waste to the taps when wet pipe works are different PD cross bond it should do it.
 
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davesparks said:
When you measured the current in the earthing conductor how did you manage to measure AC and DC seperately?
What were you looking for when you measured this current?
Click to expand...

My multimeter measures AC and DC seperately (I've no idea where the DC component comes from!). Metrel MD 9030. I was testing to see if the supplier's earth was truly at earth potential. There are other more direct ways to do it but I wanted to see what was actually happening in the house.
 
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I agree with a couple of you that bonding the bath waste to the taps should solve the 'tingles' problem but that will be masking a possible issue with the supply earth. I will do it anyway. But I'm not happy with the PD between the suppliers earth and ground.
 
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Piratepete said:
My multimeter measures AC and DC seperately (I've no idea where the DC component comes from!). Metrel MD 9030. I was testing to see if the supplier's earth was truly at earth potential. There are other more direct ways to do it but I wanted to see what was actually happening in the house.
Click to expand...

How can it measure AC and DC current seperately in the same conductor? I think you will find it is measuring AC current on both ranges but is giving a false reading on the DC range as it is trying to make sense of an AC!
That looks like multimeter according to google, did you disconnect the earthing conductor and inset this meter in to it? Or do you have a clamp type adaptor for it?

Of course the suppliers earth isn't at the earth potential of the local ground, did you expect it to be?
 
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