As I stated in my other thread I believe 5839 is wrong on this issue and it hasn't been thought through by the people writing the standard. In James first post i'll just highlight what is wrong and why. I am of the personal belief that fire alarm cables can be ran along side mains with no issues what so ever. I have ran this idea past many tradesmen, technicians and manufacturers and not one has yet to disagree other than "regulations say so" 5839 is a good practice guide for the installation of an electrical circuit. Nothing more, nothing less. It doesn't have different characteristics and doesn't behave any differently from any other type of circuit and should be treated exactly the same in terms of use, protection and segregation. What is stipulated in 5839 is GREY at the best of times and to me, is just plain old best practice. We all know best practice is what we strive towards and work with but it's not always achievable. The situations that i'm referring to when I say that 5839 is when there is no segregation available, the situation is too awkward to provide it or you have the chance to save yourself some money and hours.
I understand that if you work in this way it's not to best practice and requires a variation. Which in itself is silly because you can do anything you want to a fire alarm as long as you pass on the responsibility so hey, who cares? But 5839 is too grey to be considered a concrete technical document. If they don't want people to interpret and implement then they need to remove the factors that allow it in the first place. In my opinion a solid technical idea should be used over best practice. The inspectorate would rather you spend time and money and have everything done to the letter of the law because at the end of the day it's not their time, nor their profit that they are pissing down the drain. They get to come at the end of the job, when all the hard work and swearing has been done and then pick things off.