I can help
What city and state are you located in so I can look at your local Building Code?
Let me know when you come back online
Sorry about the phone call. I am in the US and not sure what a phone call to Australia would be. Do you mind using the online Chat?
1. What type of cabling or conduit do you have buried? (direct burial cable, rigid conduit, etc)
2. How thick is your concrete driveway slab?
Here are the National Electric Code requirements, take a look and let me know if you have any questions.
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Ok, sorry to bother you.
Good Luck with your issue!