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Cross sectional area of a protective conductors

MS01
Can someone give me a some advice on if we have a earth electrode system made up of the structural rebar when using the adiabatic equation to size of the bonding conductor comes out at 300mm. MY questions is does each bond need to be this size or can it be made up via a series of smaller bonds that are equal or exceed the 300mm requirement? My opinion is each bond needs to be this size to deal with the fault current as the direction it will flow is unknown. What are peoples thoughts? I cannot see anything in the regs on this.

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    MS01 - I'm sure you are confusing potential fault current PFC (Live to Live or Live to Neutral) with potential earth fault current PEFC (Live to earth). 


    I'm no engineer so I hesitate to comment (Let alone with an installation of this size) but the I understand that the impedance of the Live to Neutral fault path  give you an approximation of the PFC - and if you multiply this by root 3 you'll get an approximation of the live to live fault current.


    The live to earth (PEFC) size depends on the live to earth impedance. As shown above by AJ - this'll only be 168 Amps......And that'll be your main earth fault path I believe. 


    When you say you have an earth electrode system made up of structural rebar - is this what needs bonding?


    I must be missing something.........


    If you look at Table 54.8 in the regs book - page 203 - this would indicate that your main bonding size should be circa 50mm if its PME or if you look at 544.1.1 - 25mm if TNS. It doesn't seem to have any limitations on this size.....


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    MS01 - I'm sure you are confusing potential fault current PFC (Live to Live or Live to Neutral) with potential earth fault current PEFC (Live to earth). 


    I'm no engineer so I hesitate to comment (Let alone with an installation of this size) but the I understand that the impedance of the Live to Neutral fault path  give you an approximation of the PFC - and if you multiply this by root 3 you'll get an approximation of the live to live fault current.


    The live to earth (PEFC) size depends on the live to earth impedance. As shown above by AJ - this'll only be 168 Amps......And that'll be your main earth fault path I believe. 


    When you say you have an earth electrode system made up of structural rebar - is this what needs bonding?


    I must be missing something.........


    If you look at Table 54.8 in the regs book - page 203 - this would indicate that your main bonding size should be circa 50mm if its PME or if you look at 544.1.1 - 25mm if TNS. It doesn't seem to have any limitations on this size.....


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