Discussing some work with an electrician including upgrading the tails from 16mm2 to 25mm2
We are on a TT system. All circuits are protected by 30mA/30ms RCBO or RCD as well as 100mA/100ms Type S as the main switch on the CU.
He said that the cable going to the earthing point needed to be increased in CSA.
That got me thinking - Why is there a minimum size requirement for any of the earth conductors? What fault condition could cause more than 100mA to flow down any cable for more than a short period before the RCD or RCBO trips?
I read this, but it didn't answer my question.
https://www.voltimum.co.uk/articles/sizing-main-protective-bonding-0
I did ask the electrician but he couldn't really explain why it was needed. Just curious.
We are on a TT system. All circuits are protected by 30mA/30ms RCBO or RCD as well as 100mA/100ms Type S as the main switch on the CU.
He said that the cable going to the earthing point needed to be increased in CSA.
That got me thinking - Why is there a minimum size requirement for any of the earth conductors? What fault condition could cause more than 100mA to flow down any cable for more than a short period before the RCD or RCBO trips?
I read this, but it didn't answer my question.
https://www.voltimum.co.uk/articles/sizing-main-protective-bonding-0
I did ask the electrician but he couldn't really explain why it was needed. Just curious.