These are LV devices? ACB = Air circuit breaker and MCCB = moulded case circuit breakers have the AF/AT concept. I have only ever seen this AF/AT used in a limited number of countries (e.g. Singapore) and only on low voltage. So installing an 800 A trip unit in a 1200 A CB means that the circuit...
I assume that the ground is either sand or poor soil or a mixture of these, and is quite dry most of the time. Not sure why you say the earths are only 1 m deep ; is this as far as they can be driven before hitting rock?
One method is to run the earth grid to a place where the ground is damp...
