10mm meter tails 60amp fuse 6mm bond

[simpson93]

Afternoon all been a while since I've posted.


at today's job I noticed 10mm meter tails with 6mm bonding and although my first thoughts were tails should be min 16mm and bonding 10mm

so at the risk of sounding stupid I couldn't find the exact reason why this was wrong as the 10mm would take 61amps

could anyone clear this for me?

 

[JohnS888]

V/Ze= 766A

I=766
T=0.16
K=143 (not incorporated in a cable or bunched)

766x766=586756

586756x0.16=93880

square root of 93880=306

306/143=2.13mm for your main earthing conductor.

Taking reg 544.1.1 in to account the 6mm bonding conductor is adequate.

Edit: Based on a BS1361 fuse

Hi Lee or anybody else. Can you confirm what the T value of 0.16 relates to with this calculation?

Thanks

 

[JohnS888]

V/Ze= 766A

I=766
T=0.16
K=143 (not incorporated in a cable or bunched)

766x766=586756

586756x0.16=93880

square root of 93880=306

306/143=2.13mm for your main earthing conductor.

Taking reg 544.1.1 in to account the 6mm bonding conductor is adequate.

Edit: Based on a BS1361 fuse

Hi Lee or anybody else. Can you confirm what the T with value of 0.16 relates to here?

Thanks

 

[ronalsparks]

The supply authority and utility provider will expect to see 16mm tails and therefore a 10.0mm bond is required to satisfy their requirements also. The regs and calculations can determine other values but to ensure you meet the minimum requirements of the energy supplier this is what I would install as a contractor.