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APE37

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Hi guys another q I would like to clear up,
when testing to confirm a pipe is extraneous in an existing install I use the equation 230/0.01 =23000ohms - 1000ohms= 22000ohms.
when carrying out the test I test from the earth block to the pipe in question.
just looking to confirm as I have just read on another post and site that you should pull the main earth out from supply cable and test from that ( obviously isolating the install first) so not to have any parallel paths
just wondering now weather I am right or wrong as in the G N 8 it states to test from MET so just looking for opinions as I have now got confused.
Cheers
 
Hi guys another q I would like to clear up,
when testing to confirm a pipe is extraneous in an existing install I use the equation 230/0.01 =23000ohms - 1000ohms= 22000ohms.
when carrying out the test I test from the earth block to the pipe in question.
just looking to confirm as I have just read on another post and site that you should pull the main earth out from supply cable and test from that ( obviously isolating the install first) so not to have any parallel paths
just wondering now weather I am right or wrong as in the G N 8 it states to test from MET so just looking for opinions as I have now got confused.
Cheers
https://www.youtube.com/watch?v=v38PfIVy2rI hope this helps
 
Pete you linked me that video some time ago, thanks again.

I've summarised it because he doesn't get to the point until the last minute.

IR tester - measure between a known earth and the metal.
A value of equal to; or less 0.02 M ohm it’s a extraneous conductive part.
> 0.02 M ohms it’s just a piece of metal.

Would you, or anyone else, agree with my summary ?
 
Pete you linked me that video some time ago, thanks again.

I've summarised it because he doesn't get to the point until the last minute.

IR tester - measure between a known earth and the metal.
A value of equal to; or less 0.02 M ohm it’s a extraneous conductive part.
> 0.02 M ohms it’s just a piece of metal.

Would you, or anyone else, agree with my summary ?
But when does the piece of extraneous pipe need bonding?
 
I don't believe it does if circuits are protected by RCD even in a special location.
 
There's a reg in section 7 outling the 3 requirements to be met
so you don't need supplementary bonding
one is rcd protection, main water bonding and something else, I'd have to look it up. :D
 
I will watch it again, and will do research all around the topic.
Take advice from experienced people, such as yourself.
And will look out for it in any situation I come across it.
That's how I roll, and that's why I'm here. :D
 
I will watch it again, and will do research all around the topic.
Take advice from experienced people, such as yourself.
And will look out for it in any situation I come across it.
That's how I roll, and that's why I'm here. :D
Trust me, I need to watch videos like this to understand it!. To assist, I think your referring to re 701.415.2. Which go's on to say that all supplementary bonding may be omitted if items iv) to vi) apply. iv) says all extraneous conductive parts are effectively connected to protective equp' bonding. For that, 'Note' at the bottom refers to reg 415.2.2. Have a butchers at John Wards vid, goes into that in better detail than I can explain. Quite long vid, but worth watching to understand the reg. :)
 
Trust me, I need to watch videos like this to understand it!. To assist, I think your referring to re 701.415.2. Which go's on to say that all supplementary bonding may be omitted if items iv) to vi) apply. iv) says all extraneous conductive parts are effectively connected to protective equp' bonding. For that, 'Note' at the bottom refers to reg 415.2.2. Have a butchers at John Wards vid, goes into that in better detail than I can explain. Quite long vid, but worth watching to understand the reg. :)
Thanks I'll check out the JW video, a lot of the time I have to look at dozens of sources explaining the exact same thing to find the one that makes the coin drop for me. When I understand I go back to the expalanations I couldn't understand before, to see what extra I can gain. Thanks again !
 
Is the metal extraneous? If in doubt then a test will confirm this.

Test between the metal in question and the earthing conductor of the installation. The installation should be isolated from the supply before the test is carried out for obvious reasons.
IR @ 500V, A reading greater than 22Kohms will indicate that it is not extraneous. Below this value and Bonding is required.

Ohms Law. GN8 goes more in depth on the subject in regards to calculations and shock currents. The designer is the person who takes account for what is acceptable etc.

Happy to be corrected and learn something myself. Is it not just ohms law at the end of the day and a basic understanding of how to apply principles and science to ensure safety?
 
Reg. 415.2.2 gives an equation or formulae to calculate resistance R (max) between simultaneously accessible exposed-conductive parts & extraneous conductive parts. Below that figure it is effectively connected. Above that figure & below 22000 ohms, it requires bonding. Above 22000 ohms, as Mr Kitcher explains, its just a piece of metal.
 
The way it was explained to us, was each arm of your overalls was clamped in a bench vice by ya fellow apprentices, and another zapped you across each hand with a megger. Shocking.
 
What reading/value of ohms does it require bonding? For circuits protected by RCD e.g.?

Look at the first bit of the video and take note of where Chris derives the formula from, hint RCD operating current.
 
Look at the first bit of the video and take note of where Chris derives the formula from, hint RCD operating current.
Preaching to the converted Pete. I was trying to get the others guys to find out themselves without spoon feeding them. Also useful to note the reg applies to over current devices.
 

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