and how does a managed protocol stop the untrained 'handyman' having a go?

It doesn't and I doubt whether anything will ever stop that. It does however stop the 'Mr yesterday I was an electrician today I am a fire alarm engineer' working on the system, and therefore offers peace of mind for the client as he knows the engineer working on the system is suitably qualified.

how?

Because the engineers are suitably trained prior to working on the systems and have the correct tools for the job.

I get you mate i really do, but in all honesty.

If using a pro company with the correct ideals who wouldnt work on a system they had no access to (ie us) id agree. But a spark who thinks he knows fire.... whats the difference between them and the handyman. It can still be worked on, just they are more likly to disable things or bodge thing

I think we've established that nothings gonna stop the handyman having a go at anything, be it fire, intruder or....servicing the MD's car.

I'm looking at it from a clients perspective, at the end of the day he has a duty to ensure that his fire system is maintained by a suitably trained engineer, if he chooses to have it done by the handyman or local spark who claims to know what he's doing he's leaving himself at risk of the system failing or not functioning correctly. Managed protocol eliminates this risk as only trained engineers have the correct tools and support to work on the system.

I'm sure the MD wouldn't choose to have his Merc serviced at the local Fiat dealers.

lol maybe.

Id hope that companies wouldnt allow 'just anyone' to service / work on their fire system. Unfortunatly and the amount we turn down i know that isnt the case. Many people with mercs now dont have em serviced by merc..... till they go wrong then that