kiwi,
Section 51A(??) of the Fire Service Act says that you are not allowed to render a disconnect ineffective by a lock, even if the local Brigade has a key.
One idea would be to render that switch inoperative and switch it by remote control.
Hence making that switch a contactor and having a Fire Switch somewhere else that the Brigade knows about, but not telling anyone else apart from those that should know it's position and function.
Keys are one thing that really hold us fire crews back.
The building might be fully involved, but you can't get near it until the key-holder turns up.
