bonding services

[davie spark]

If the' part' is part of the electrical installation or it is bonded to part of the electrical installation, you do an earth continuity test.

 

[IQ Electrical]

To test if something is extraneous do you not do an ir test to earth

Precisely, an IR test is the only way to define an extraneous-conductive part.

If the reading between the part and the MET is greater than 22kOhms then the part is not considered to be an extraneous-conductive part.

 

[i=p/u]

Think thats it stuck forever...

 

[davie spark]

To test if something is extraneous do you not do an ir test to earth

Only if the part is not already bonded, if it is already bonded, as it might be, you would carry out and earth continuity test on the bonding conductor. Whilst not wishing to confuse this thread further, there are instances where extraneous conductive parts may be required to be bonded (to provide equalisation of voltage under fault conditions), but not earthed and where transformers and data wiring is present the testing of non earthed bonding of these types of extraneous parts can only be confirmed by earth continuity testing.

 

[IQ Electrical]

Only if the part is not already bonded, if it is already bonded, as it might be, you would carry out and earth continuity test on the bonding conductor. Whilst not wishing to confuse this thread further, there are instances where extraneous conductive parts may be required to be bonded (to provide equalisation of voltage under fault conditions), but not earthed and where transformers and data wiring is present the testing of non earthed bonding of these types of extraneous parts can only be confirmed by earth continuity testing.

You have confused the thread further, in your previous post you mention a continuity test and a reading of 0.5 Ohms, where is this test defined?

 

[i=p/u]

0.05 ohms, dont think its a reg but is in some guidance and learning books

 

[IQ Electrical]

0.05 ohms, dont think its a reg but is in some guidance and learning books

The 0.05 Ohm figure is between parts that require supplementary bonding but NOT back to the MET.

There is no maximum resistance specified in BS7671:2008 for main protective bonding conductors.

 

[i=p/u]

Jus the set csa sizes in regs i.e 6mm tn-s 10mm tn-c-s etc. So the 0.05 ohms is to see if it requires supplementry bonding but in which case doesnt be required if you have main bonding fulfilled???

 

[i=p/u]

ALSO THE ADIBIATIC IS NOT FOR MAIN BONDING AS THESE ARE SPECIFIED, BUT CAN USE TO CHECK OLDER INSTALLATIONS??? IL READ YOUR AWNSER WHEN I SIGN Back on, gotta shoot, cheers wise one, i will learn regs inside out and make you proud... and earn myself a small fortune is the plan...

 

[IQ Electrical]

ALSO THE ADIBIATIC IS NOT FOR MAIN BONDING AS THESE ARE SPECIFIED, BUT CAN USE TO CHECK OLDER INSTALLATIONS??? IL READ YOUR AWNSER WHEN I SIGN Back on, gotta shoot, cheers wise one, i will learn regs inside out and make you proud... and earn myself a small fortune is the plan...

Too late tonight to go through your last 2 posts but I'll take a look in the morning!

 

[MarkieSparkie]

The 0.05 Ohm figure is between parts that require supplementary bonding but NOT back to the MET.

There is no maximum resistance specified in BS7671:2008 for main protective bonding conductors.

GN3 2.7.5 Continuity of protective conductors including main and supplementary bonding. Test Method 2. The “water is muddied” here in the usual IET fashion, by a less that explicit inference, that leads to alternative interpretation.
“To confirm the continuity of a bonding conductor, the leads from the instrument are connected to each end of the conductor and a reading is taken. One end of the bonding conductor and any intermediate connections with services may need to be disconnected to avoid parallel paths.”
“This method can also be used to confirm a bonding connection between extraneous-conductive-parts where it is not possible to see a bonding connection, e.g. where bonding clamps have been 'built in'. The test would be done by connecting the leads of the instrument between any two points such as metallic pipes between which a bonding connection was required and looking for a low (minimal deflection) reading of the order of 0.05 Ohms or less.”
IMO this does apply to Main Bonding Conductors by inference.
The resistance (R) of Supplementary Bonding Conductors between simultaneous accessible exposed-conductive parts and extraneous-conductive-parts need only meet the generally less onerous (most domestic installations certainly) R<= 50V/Ia in an AC system where Ia is the operating current of the protective device, for RCDs Idelta n and for overcurrent devices, the current cause automating disconnection in 5s, 415.2.2

 

[GaryM]

Short answer, you can combine both bonds in one cable as long as you don't cut the cable. Double over the cable at the first bonding point and fit a crimp of suitable size, then bond the remaining utility using a crimp suitable for the cable size. Appropriately label the conductor at the main earth terminal.

You crimp a 'doubled over' 10mm2 conductor? In what, a 25mm2 lug? I'm not convinced that will be a reliable connection. Also you're not following the MI for the lug so therefore in breech of BS7671.
As I said above, nothing to stop you cutting the bonding cable and fitting two 10mm2 lugs then loop to the next service. There's a warning label in place at each location to warn about removal.

 

[malcolmsanford]

I have never liked the idea of 6mm and now 10mm conductors, somehow connected as a whole onto a BS 951 clamp. The clamps are not the greatest of design IMO and to be honest it never seems to be a good mechanical connection.

I would always try to run separate bonding conductors to the services, but if I did need to daisy chain the services I'm with Gary a 10mm crimp connector IMO makes a much better connection mechanically than "eyeing" a 10mm cable and trying to get a good connection. As Gary said they are all labeled with advice about not removing and if a plumber can't read then so be it.

 

[IQ Electrical]

GN3 2.7.5 Continuity of protective conductors including main and supplementary bonding. Test Method 2. The “water is muddied” here in the usual IET fashion, by a less that explicit inference, that leads to alternative interpretation.
“To confirm the continuity of a bonding conductor, the leads from the instrument are connected to each end of the conductor and a reading is taken. One end of the bonding conductor and any intermediate connections with services may need to be disconnected to avoid parallel paths.”
“This method can also be used to confirm a bonding connection between extraneous-conductive-parts where it is not possible to see a bonding connection, e.g. where bonding clamps have been 'built in'. The test would be done by connecting the leads of the instrument between any two points such as metallic pipes between which a bonding connection was required and looking for a low (minimal deflection) reading of the order of 0.05 Ohms or less.”
IMO this does apply to Main Bonding Conductors by inference.
The resistance (R) of Supplementary Bonding Conductors between simultaneous accessible exposed-conductive parts and extraneous-conductive-parts need only meet the generally less onerous (most domestic installations certainly) R<= 50V/Ia in an AC system where Ia is the operating current of the protective device, for RCDs Idelta n and for overcurrent devices, the current cause automating disconnection in 5s, 415.2.2

Hi Mark, just leaving your opinion to one side, read the text above again with regards to the 0.05 Ohm value.

Then check out this thread http://www.electriciansforums.net/e...o-you-work-out-when-go-up-10mm-16mm-so-4.html , there is an email from Paul Bicheno from the IET Standards & Compliance explaining the above.

 

[i=p/u]

it says in chris kitchers book max lengths of bonding conductors ,10mm 27M, 16mm 43M.. so doesnt exceed 0.05 and you saying he is wrong.... i thought was great book too...