Thanks for the suggestion Crosby. Attached is a pic of the main board and breaker box.
You will note that the under/ over current device is currently disconnected.
The Schneider 3P + N MPD has been quoted at Thb12k.
iPRD65r modular surge arrester - 3P + N - 350V - with remote transfert
https://www.se.com/ww/en/product/A9L65601/iprd65r-modular-surge-arrester---3p-%2B-n---350v---with-remote-transfert/