Upgrade 'earthing' conductor on CU im not working on?

[VMan]

ok, been to a job today, put in tail blocks and a shower CU (along with bonding), the existing CU is still in use and only has a 2.5mm earth from earth block to CU earth bar. Its only a short run and going to slap a 10mm in there, but would i have to?

I know its a small job easy and thats why im doing it but the idea of putting in the new CU is so i don't have to alter the existing installation, just wondering where i stand as this could be potentially dangerous if left. and the question was asked by a colleague if i had to do it?

Thanks for advise in advance.

 

[telectrix]

once you do that, you will have to ensure the main bonding is compliant, or have you already done so in with the job you're doing?