Extraneous and bonding etc

[uksparks]

Hi,

something that cropped up yesterday on my assessment was that I'd done a load of work on a house and new CU etc.

the old boiler had been taken out and a new one fitted but the gas supply had not been put into the new boiler.

the old gas pipe was left where the old boiler was in a different part of the house.

i didn't bond the old pipe as it was about to be removed and a new one put in.

he said why have you not bonded the gas pipe?

i said it was about to be removed.

i said I have done an IR on it to the MET and it suggested it was not extraneous or already bonded somewhere so was not bothered as I felt it to be satisfactory.

he said what do you mean you have done an IR test in it?

so I explained it was less than 0.03M ohms, it was 0.00 as it happens, so it was less that 23,000 ohms. He said that it should be well over 1 meg ohm. I had to agree to disagree, I said yes but I'm proving it's not extraneous....

am am I right or am I being thick?

 

[Simonslimline]

Re: Extraneous and binding etc

A reading greater than 22k ohms would prove it is not extraneous. Show him GN8 if he thinks you are wrong, it is all explained in there.

Edit...

It is 23k i believe but 1k is deducted for the body resistance.

230V / 23000 Ohms = 0.01A

 

[Richard Burns]

Re: Extraneous and binding etc

I can see why you would not bond something that was about to be removed, even thought the regulations would have otherwise (what happens if a fault occurs before it is removed!!).

Electrically you are actually conducting a high value resistance test that is most easily done with an IR tester.

You proved that it was an extraneous part because the resistance to the MET was less than 23 kohms and so it would require bonding.
If you measured with a low resistance ohmmeter and got a very low value (hundredths of an ohm) then you could assume it was electrically connected to the installation, but whether with a large enough conductor is another matter.

Overall from what you say I would say it should have been bonded but this would be redundant in a short time and so had been left as it was electrically (perhaps) connected to the MET anyway.

 

[Baker1988]

Re: Extraneous and binding etc

Hi,

something that cropped up yesterday on my assessment was that I'd done a load of work on a house and new CU etc.

the old boiler had been taken out and a new one fitted but the gas supply had not been put into the new boiler.

the old gas pipe was left where the old boiler was in a different part of the house.

i didn't bond the old pipe as it was about to be removed and a new one put in.

he said why have you not bonded the gas pipe?

i said it was about to be removed.

i said I have done an IR on it to the MET and it suggested it was not extraneous or already bonded somewhere so was not bothered as I felt it to be satisfactory.

he said what do you mean you have done an IR test in it?

so I explained it was less than 0.03M ohms, it was 0.00 as it happens, so it was less that 23,000 ohms. He said that it should be well over 1 meg ohm. I had to agree to disagree, I said yes but I'm proving it's not extraneous....

am am I right or am I being thick?

i think it should be more than 22k so the 0.00ohm reading is too low

 

[uksparks]

Re: Extraneous and binding etc

Greater than or less than? I'm confusing myself now, if I measure a pipe, any pipe and it's say 0.03M then that's greater than 23k.

if it's 0.02 for example then that's less than 23k.

 

[Simonslimline]

Re: Extraneous and binding etc

worth a watch




https://www.youtube.com/watch?v=v38PfIVy2rI

 

[uksparks]

Re: Extraneous and binding etc

Yes you are right, I'm confusing myself that's the issue.

I did explain to him it was less than 0.05 ohms between them on continuity which to me suggests it's bonded.

the pipe is coming out this week anyway.

 

[HappyHippyDad]

Re: Extraneous and binding etc

Was the test 0.00 as in first post UK or 0.05 as in last post? First post suggests it is connected to MET somewhere but I'm confused with the 0.05 figure, that would be 50,000Ω. I guess you could have done a continuity check just to see if the figure was below 1667Ω then if RCD protected it would be ok.

 

[Richard Burns]

Re: Extraneous and binding etc

I think the first is 0.00 Mohms the last is 0.05 ohms.

RCD protection doe not remove the requirement for bonding, bonding is there so that in the case of a fault to earth all accessible conductive parts will be at the same voltage prior to the disconnection occurring.

 

[uksparks]

Re: Extraneous and binding etc

Sorry I realise what I've said.

it was 0.00Mohms IR between the water and gas so zero M ohms.

IR tester will only go down to 10,000 ohm resolution yes?

anyway when I tested with a low resistance ohmmeter between the same two bits of pipe it was less than 0.05 ohms, which would obviously show as zero on IR as it's less than 0.01M ohms ok.

Ok, so can you not say there's clearly continuity between the two pipes yes? Sufficiently to say they are well connected somehow ?

am I just being a total spanner here?

 

[uksparks]

Re: Extraneous and binding etc

Oh just for the record I'm not one for saying it's rcd protected so it's ok.

 

[HappyHippyDad]

Re: Extraneous and binding etc

You're quite right Richard. UK clearly states 0.05ohms on a continuity check. Also quite right about the bonding.. I was getting confused with supplementary bonding. It's too late for me!

 

[uksparks]

Re: Extraneous and binding etc

He was trying to suggest if was extraneous and needed bonding but I could only see that it was like touching the same bits of pipe together from the readings?

 

[HappyHippyDad]

Re: Extraneous and binding etc

Sorry I realise what I've said.

it was 0.00Mohms IR between the water and gas so zero M ohms.

IR tester will only go down to 10,000 ohm resolution yes?

anyway when I tested with a low resistance ohmmeter between the same two bits of pipe it was less than 0.05 ohms, which would obviously show as zero on IR as it's less than 0.01M ohms ok.

Ok, so can you not say there's clearly continuity between the two pipes yes? Sufficiently to say they are well connected somehow ?

am I just being a total spanner here?

I would have thought so! Hopefully Richard will tell us :smiley2:

 

[Silly Sausage]

Re: Extraneous and binding etc

You're quite right Richard. UK clearly states 0.05ohms on a continuity check. Also quite right about the bonding.. I was getting confused with supplementary bonding. It's too late for me!

Time to hit you with this then!

http://www.copperalliance.org.uk/do...thing-practice-pdf.pdf?Status=Master&sfvrsn=0