You will notice the image here of a breaker locking device.  The device complies with NEC 110.25 as a permanent locking means for the fire alarm and does a great job of directing firemen to the disconnect during a fire response call.  There are many of these devices on the market, all of which do a great job.  Before you install one in your area, you will want to check with the local Fire Marshall.  Sometimes your local jurisdiction has specific types of equipment they would like you to use, to keep all panels in their area uniform.