Is it necessary to use the protection shield on the top side of the Compact NS>630 if the breaker is mounted in horizontal position.

The white protection shield at the top side of the breaker is for protection and isolation of the bare cable connectors against gas exhaust.

Hence it is always necessary to use protection shield irrespective of the breaker mounting position.

Note: It is not necessary at the down side because the hot gas exhaust is always from the top.