I do seem to getem!

[Piratepete]

Isn't that the whole point of Bonding?!

No. The point of bonding is to stop electrocution in case of a fault. It doesn't fix the fault!

It's like taking painkillers so that youcan carry on working! lol

 

[davesparks]

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.

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?

 

[davesparks]

No. The point of bonding is to stop electrocution in case of a fault. It doesn't fix the fault!

It's like taking painkillers so that youcan carry on working! lol

The point of bonding is to maintain an equipotential zone.

 

[Charlie_]

You said that a new TNS supply has just been installed, what was the previous set up?

 

[davesparks]

A new cutout has been installed, the TNS supply is original

 

[shanky887614]

if it is definitely external to the property the only thing you can do is report it and hope the dno follows it up

 

[Geordie Spark]

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

Is this bath an iron bath??

 

[Geordie Spark]

Yes. I'm hoping the side panel will be deconstructd by the morning!

If the pipes supplying the bath taps are copper it could be worth chopping a lump out of both the hot & cold ( say about 8 inches) and sticking a bit of plastic in its place (Speedfit for example)

Same goes for the basin.

If the bath is iron, then consider replacing he lead waste with 40mm plastic.

These measures are not intended to be a substitute to finding and fixing the fault it's more like an extra line of defence if you like.

 

[Silly Sausage]

No. The point of bonding is to stop electrocution in case of a fault. It doesn't fix the fault!

It's to cancel out potentials external to the installation.

You should get a job at NICEICE or a politician!

 

[marc8]

Hi the problem at the hall toilets was:

the earth system was TNS so at the origin of supply you have an earth point at X amount of ohms
you have water & maybe gas bonding connected to this point bringing them to the same potential or close to it.
Then you have maybe your bath waste being metal at a different point could be 10-20 meters away could even be next to the cut out this if metal is going into the ground creating another point to earth at say XX.
When the water is run in the bath or in our cAse was the sink & you touched the taps whilst your hand was in the water you would get the tingling sensation our case was because we got around 65v difference, I believe touch voltage 50v am I correct not sure, now under Dry conditions you would not as likely feel this but when your hands ect are wet you are feeling it. (& touch voltage value is halved)
This is because the earth points are at different potential points as it would be in the above as the mass of the earth at the two different points is different.
also before our problem occurred we had just installed cross bonding to all hot & cold pipe work but could not see the metal waste when cross bonded with others what happened ... They were at the same potential or close to it so no more problem.
What made more Intresting was during testing we found neutral outside was breaking down at the pole joint & we had just had it repaired also.

With regard to chopping out a bit of pipe on the hot &'cold water pipes at the bath, what do you think this will do as water is conductive & unless they are running a sand bath there is nothing this will do. Now if you replaced the bath wate with plastic & into hopper or plastic soil stack that would work why bother though when the simple thing would be to bring them to the same potential by ? Cross bonding them together.

 

[Piratepete]

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?

Well. I thought of that and tested my meter when I got home on known 12VDC and 230VAC supplies. On that limited test the DC setting doesn't recognise the AC and vice versa. Also the DC at the bath is polarity sensitive.

I accept that the suppliers earth isn't at earth potential. But would you expect this current to flow through it? Presumably, if I bond the waste, the current will increase (960 Ohms removed).

Pete

 

[Piratepete]

It's to cancel out potentials external to the installation.

You should get a job at NICEICE or a politician!

Ok! ok!. I know that! Just stating the ultimate goal!

You're not the first to suggest I should be in politics. I did try as a Parish Councillor - not the happiest time of my life!

 

[PEG]

Hi the problem at the hall toilets was:

the earth system was TNS so at the origin of supply you have an earth point at X amount of ohms
you have water & maybe gas bonding connected to this point bringing them to the same potential or close to it.
Then you have maybe your bath waste being metal at a different point could be 10-20 meters away could even be next to the cut out this if metal is going into the ground creating another point to earth at say XX.
When the water is run in the bath or in our cAse was the sink & you touched the taps whilst your hand was in the water you would get the tingling sensation our case was because we got around 65v difference, I believe touch voltage 50v am I correct not sure, now under Dry conditions you would not as likely feel this but when your hands ect are wet you are feeling it. (& touch voltage value is halved)
This is because the earth points are at different potential points as it would be in the above as the mass of the earth at the two different points is different.
also before our problem occurred we had just installed cross bonding to all hot & cold pipe work but could not see the metal waste when cross bonded with others what happened ... They were at the same potential or close to it so no more problem.
What made more Intresting was during testing we found neutral outside was breaking down at the pole joint & we had just had it repaired also.

With regard to chopping out a bit of pipe on the hot &'cold water pipes at the bath, what do you think this will do as water is conductive & unless they are running a sand bath there is nothing this will do. Now if you replaced the bath wate with plastic & into hopper or plastic soil stack that would work why bother though when the simple thing would be to bring them to the same potential by ? Cross bonding them together.

Clean,potable water is not as conductive as you may imagine.

You can actually make a rudimentary speed control rheostat,using the varying proximity of two copper wires,in a bowl of water!

...Just adding a bit of fun :joker:

NB; Also,do not discount a possible fault occurring,in an adjacent property,where your shared soil may be receiving an unwanted input from their supply...

 

[Silly Sausage]

Clean,potable water is not as conductive as you may imagine.

You can actually make a rudimentary speed control rheostat,using the varying proximity of two copper wires,in a bowl of water!

...Just adding a bit of fun :joker:

I tried that once and ended up burning my eyebrows off.

 

[Knobhead]

Archy, ever messed about with an electrode boiler?

Not one of my better ideas but I was bored at work so knocked one up. 8KW boils a pint of water rapidly.

 

[shanky887614]

Archy, ever messed about with an electrode boiler?

Not one of my better ideas but I was bored at work so knocked one up. 8KW boils a pint of water rapidly.

care to tell the tale?

 

[PEG]

Archy, ever messed about with an electrode boiler?

Not one of my better ideas but I was bored at work so knocked one up. 8KW boils a pint of water rapidly.

Did that cup of tea, taste of thoriated tungsten,by any chance...:icon12:

 

[Knobhead]

Your joking, I used off cuts of 2x½” tinned copper busbar about 15” long. Lead, tin and copper would make it your last cup of tea.

I’d read about electrode boilers and as I was bored one Sunday afternoon at work I decided to have a play. It was only a square plastic bowl with the sections of busbar along opposite sides, 250V between them. The power can be regulated by altering the distance between the bars. I got it up to about 12KW 45A before blowing the 32A fuse. It gets downright violent once the temperature is getting close to boiling point. The workshop was like a sauna.

On a Sunday all the plants would be running flat out, if nothing broke down I’d got time to kill. I found something to keep me entertained for a while.

This is not an experiment to try at home! A/ it’s dangerous, B/ you’ll have to pay the lecy bill!

 

[maggot]

I had exact problem turned out to be poor Ze, bonding provided better return path, changed to TT problem solved.
try whacking an earth stake in

 

[Geordie Spark]

Hi the problem at the hall toilets was:

the earth system was TNS so at the origin of supply you have an earth point at X amount of ohms
you have water & maybe gas bonding connected to this point bringing them to the same potential or close to it.
Then you have maybe your bath waste being metal at a different point could be 10-20 meters away could even be next to the cut out this if metal is going into the ground creating another point to earth at say XX.
When the water is run in the bath or in our cAse was the sink & you touched the taps whilst your hand was in the water you would get the tingling sensation our case was because we got around 65v difference, I believe touch voltage 50v am I correct not sure, now under Dry conditions you would not as likely feel this but when your hands ect are wet you are feeling it. (& touch voltage value is halved)
This is because the earth points are at different potential points as it would be in the above as the mass of the earth at the two different points is different.
also before our problem occurred we had just installed cross bonding to all hot & cold pipe work but could not see the metal waste when cross bonded with others what happened ... They were at the same potential or close to it so no more problem.
What made more Intresting was during testing we found neutral outside was breaking down at the pole joint & we had just had it repaired also.

With regard to chopping out a bit of pipe on the hot &'cold water pipes at the bath, what do you think this will do as water is conductive & unless they are running a sand bath there is nothing this will do. Now if you replaced the bath wate with plastic & into hopper or plastic soil stack that would work why bother though when the simple thing would be to bring them to the same potential by ? Cross bonding them together.

Are you sure about that??

Try a little experiment sometime with two bits of copper pipe joined together by a bit of plastic pipe about a foot long, fill with water and stick your meter on it.