Extraneous conductive parts

[Deleted member 26818]

No not really.
It indicates that the metallic pipe is in contact with earth but as I’ve said, it’s not connected to the MET and has no continuity to it when using a wander lead to test it from the MET to the pipework.
The test I’ve done says to me it’s extraneous as it has a very low resistance to earth.
If it was connected to the MET then I’d have continuity

No, it does not indicate that metallic pipe is connected to earth. It indicates that there is a reliable connection between the metallic pipe and the MET.

Your second posts states: you have zero resistance between the metallic pipe and the MET and no continuity between the metallic pipe and a known earth.
Now you appear to be saying the opposite.
Please clarify.

 

[Ian1981]

No, it does not indicate that metallic pipe is connected to earth. It indicates that there is a reliable connection between the metallic pipe and the MET.

Your second posts states: you have zero resistance between the metallic pipe and the MET and no continuity between the metallic pipe and a known earth.
Now you appear to be saying the opposite.
Please clarify.

Right there’s no continuity between MET and pipe when carrying out a continuity test.
There a reading of 0.00 Mohms between the source of earth to the installation (not at the MET as I disconnected it doing the IR test).
Conclusion is that the metallic pipe is in good contact with earth(externally) and is extraneous but it is NOT connected to the buildings earthing.
Got it??

 

[Pete999]

Right there’s no continuity between MET and pipe when carrying out a continuity test.
There a reading of 0.00 Mohms between the source of earth to the installation (not at the MET as I disconnected it doing the IR test).
Conclusion is that the metallic pipe is in good contact with earth(externally) and is extraneous but it is NOT connected to the buildings earthing.
Got it??

I have thanks

 

[Ian1981]

The discussion isn’t or isn’t it extraneous , it’s if it’s accessible in the sense that it requires bonding and it probably should.

 

[Deleted member 26818]

So why did you say this:

Testing from the MET or rather the source of earthing to said pipe.
Main earthing conductor disconnected from source earth
IR set to 500v reading of 0.00 Mohms
Also no continuity between said pipework and a known earth source

If you tested IR between the MET (with the Main earthing conductor disconnected) and the pipe, to obtain a reading of 0.00 Mohms, that would indicate a reliable connection between the pipe and the MET.
To then state there is no continuity between said pipe work and a known earth source, would indicate no connection to earth.
Are you now saying, you did not test IR between the MET and the pipe, that in fact you tested between the Earthing conductor and the pipe?
If so what does the statement that there is “also no continuity between said pipework and a known earth source” mean?

 

[Ian1981]

So why did you say this:

If you tested IR between the MET (with the Main earthing conductor disconnected) and the pipe, to obtain a reading of 0.00 Mohms, that would indicate a reliable connection between the pipe and the MET.
To then state there is no continuity between said pipe work and a known earth source, would indicate no connection to earth.
Are you now saying, you did not test IR between the MET and the pipe, that in fact you tested between the Earthing conductor and the pipe?
If so what does the statement that there is “also no continuity between said pipework and a known earth source” mean?

The source of earthing is what the DNO provide for the installation.
A known earth source is exactly that, a point in the installation such as the MET that’s connected to the earthing arrangement in the building.
My 2nd post in the thread is clear enough.
Testing the metallic pipe was done in accordance with gn8 pages 74 and 75.
Testing between earth and the suspect pipework using an insulation resistance tester set at 500 volts D.C. and the reading being less than 22Kohms or as displayed on my instrument 0.00 Mohms.
Have a read up on it why don’t you?

 

[magnoliafan89]

Guys im confused. If you wanted to know if a pipe or say tap could have a potential difference. What tests would you do? What results would you expect? You'll have to make the answer simple as im still just a trainee

 

[Ian1981]

Guys im confused. If you wanted to know if a pipe or say tap could have a potential difference. What tests would you do? What results would you expect? You'll have to make the answer simple as im still just a trainee

Check out pete’s uploaded videos.
Generally the formula is 230/0.01 amps (10mA being the let go threshold)
To assess whether Earth potential is liable to be introduced by a conductive part that is connected to the general mass of Earth through a resistance, a measurement should be made of the resistance between the conductive part and the main earthing terminal of the installation.
As generally our continuity meters won’t read that high say (22Kohms) then an insulation resistance meter is used set to 500v D.C. and a measurement is taken between the suspect pipework and the earth arrangement to the installation.
Also For a better technical explanation check out gn8.

 

[westward10]

The discussion isn’t or isn’t it extraneous , it’s if it’s accessible in the sense that it requires bonding and it probably should.

Bet you are glad you asked now
I think you have to say it is accessible, amen.

 

[Ian1981]

Bet you are glad you asked now
I think you have to say it is accessible, amen.

I don’t post very often problems on site and this experience has put me right off

It’s gone down as a C2 on the report

 

[westward10]

Don't be put off you are a forum member who knows his eggs.

 

[Deleted member 26818]

Be useful if he explained himself better.

 

[Pete999]

No I just wanted you to explain your statement, it seems we are getting mixed up here Spin, of course I know the reason, it was just I thought your statement was a bit far reaching. And why you feel the vids are misinforming people that's all.

What do you think Spin?

 

[Deleted member 26818]

I would be surprised if the vids are mis-informing people.
Was concerned that you appeared to be unaware that Main Equipotential Bonding relates to extraneous-conductive parts.

 

[Pete999]

I would be surprised if the vids are mis-informing people.
Was concerned that you appeared to be unaware that Main Equipotential Bonding relates to extraneous-conductive parts.

Not unaware at all Mate, maybe a wrongly worded question.

 

[DPG]

I'm sure Pete knows full well what it refers to.

 

[Deleted member 26818]

You said this:

That is for main Equipotential bonding the OP is on about extraneous two different Animals, please see the vids I have posted.

If the vids are telling you that Main Equipotential Bonding and bonding of extraneous-conductive parts are two different animals, they are mis-informing you.

 

[Pete999]

You said this:

If the vids are telling you that Main Equipotential Bonding and bonding of extraneous-conductive parts are two different animals, they are mis-informing you.

I don;t think the vids are saying that, I think what caused the confusion especially in JW's Vid is that the different Animal, comes from the description of the differences of exposed conductive parts ie part of an electrical installation that is NOT normally live, electric metal heater framework , and an Extraneous conductive part, as in water,gas, oil pipework etc that doesn't form part of the electrical installation.

 

[Deleted member 26818]

As far as I am aware, the OP was referring to a dry riser, which would not be part of the electrical installation.
The OP started off stating there was an IR of 0.00 Mohms between the riser and the MET and that there was no continuity between the riser and a known earth.

I stated that 0.05 ohms is the maximum resistance for parts bonded to the MET.
In the OP’s case, I would use a low ohm meter to determine whether the IR reading of 0.00 Mohms is below 0.05 ohms.

 

[DPG]

Is this the 5 minute argument or the 10?