Discuss Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgrade! in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

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TeeJay711

Continuity test results from the board to the isolation valve to the house and from the board to the nearest radiator has o.oo resistance on a 4mm cable do i still have to upgrade to a 10mm.
It means ripping up the floor and kitchen units in the kitchen and laminate in the hallway to put in a cable that will still give me 0.0 results.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Continuity test results from the board to the isolation valve to the house and from the board to the nearest radiator has o.oo resistance on a 4mm cable do i still have to upgrade to a 10mm.
It means ripping up the floor and kitchen units in the kitchen and laminate in the hallway to put in a cable that will still give me 0.0 results.


Tell us, ....What do you think???
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Thats some dam good 4mm
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Well, I used a 2.5mm single as a fly lead and that had 0.00 ohms and so I am concerned that the tester is incorrect but has been calibrated recently.
I can just see the cables under the floor but cant see where they are connected, my gut instinct is to rebond the whole house but i am tempted to try another tester first, what do you think!
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Humm, I think you will need to learn how to null your tester lol
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

OK, I am a bit rusty on the testing its been a few years but joking aside, there is bonding there and if my "revised"results come back low, do I have to upgrade to the 10mm.....?
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

all depends on the earthing arrangements, TNC-S you need 10mm. TN-S and TT systems, use adiabatic to determine the min. size.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

yes, by association. use adiabatic to determine the min. size for the main earth, then ensure bonding conductor/s is/are at least 50% of the csa of the main earthing conductor.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Are you sure its 4mm and not 6 mm that's installed. If it is 4 mm you can't use that as a bonding conductor its too small ! Even if TT .
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Are you sure its 4mm and not 6 mm that's installed. If it is 4 mm you can't use that as a bonding conductor its too small ! Even if TT .

Tony if he's getting 00.00 it will be a very large conductor!
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

Tony if he's getting 00.00 it will be a very large conductor!
I agree but the OP has said the CSA of the cable is 4 mm. IMO the conductor is not disconnected from the MET and other earth paths are giving false readings or something else has gone wrong with the test with 4mm giving 4.61 m/ohms /m. But in any case 4 mm as a main bonding conductor :)38:) I wonder what the job is that is being carried out !
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

all depends on the earthing arrangements, TNC-S you need 10mm. TN-S and TT systems, use adiabatic to determine the min. size.

yes, by association. use adiabatic to determine the min. size for the main earth, then ensure bonding conductor/s is/are at least 50% of the csa of the main earthing conductor.

I realise this thread is a few months old but it was similar to one I was going to start.

May as well be bluntly honest, I am trying to avoid putting in new main bonding for a CU change as the chap wont accept the job if the bonding has to be upgraded.

It a TT with 4mm Main Earthing and 4mm Main bonding.

The OSG states 6mm minimum for main bonding on a TT (which I cant quite get my head around if 2.5mm is ok for main earthing), but after reading Tel's posts above I am wondering if a lower csa is acceptable if it meets the adiabatic and is at least half of the Main earthing?
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

I realise this thread is a few months old but it was similar to one I was going to start.

May as well be bluntly honest, I am trying to avoid putting in new main bonding for a CU change as the chap wont accept the job if the bonding has to be upgraded.

It a TT with 4mm Main Earthing and 4mm Main bonding.

The OSG states 6mm minimum for main bonding on a TT (which I cant quite get my head around if 2.5mm is ok for main earthing), but after reading Tel's posts above I am wondering if a lower csa is acceptable if it meets the adiabatic and is at least half of the Main earthing?

The adiabatic equation is there to calculate the worst case fault current and usually associated with shared cpcs found in metalwork. You would then size the MPB conductor to half that size for anything other than PME systems, to a minimum of 6.0mm2.

Now an earthing conductor has a different function to a MPB conductor. The former is there to clear earth faults within the installation within the specified maximum allowable time from table 41.1 which will comply with the other tables in part 4 , 41.2, 41.3, 41.4 etc;

the latter is there to provide protection against external faults keeping the metalwork in the installation at an equal potential. It also aids protection by reducing the R2 of a faulted circuit and thus reducing the potential difference on any metalwork connected to the MET.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

if this were my job and the adiabatic confirmed that the MEC was adequate, and both MEC and MBC's showed no sign of damage, client refuses to pay for upgrade of these on a CU change, i'd go ahead with the CU, but make sure it's noted in the comments box that the earthing and bonding is not up to current standards. at the end of the day, you are making the installation safer than before, and also testing the circuits as to be safe for continued use, fixing any faults as part of the CU change.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

I would also specify that the upgrade of the bonding to meet the requirements of the regulations has been refused by the customer, but that the MPB does meet the requirements of csa when considered in relation to the minimum earthing conductor csa.
 
Re: Domestic Bonding test results has o.oo resistance on a 4mm cable do i still upgra

What sort of test equipment is he using???????
 

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