Fire alarm panel supply

OK - agreed, that there is no mention now of skilled and instructed persons - I was just trying to get the OP to think about the risk hierarchy that he is trying to address with the design given the supply is a part of a life safety system


If the fire alarm supply cable is buried in zone, then is there a very real, credible risk of a "strike" to that cable in this environment - I suspect not


It may well be that the selected cable is already compliant in terms of an earthed metallic screen or sheath - it may take some calculations to prove that


It is a requirement for a lockable isolation position so it seems entirely credible to me that the 230V supply cable would easily be installed in a length of earthed conduit from the ceiling void to the lockable isolator and then to the panel, as a flush installation


Personally, I would try to avoid at all cost the provision of RCD protection to this circuit from a life safety safety perspective.


BS 7671 excludes fire alarm systems compliant with BS 5839-1 - is the 230V feed to the panel actually a 230V fire alarm circuit ? -  and not covered by BS 7671 anyway.


Regards


OMS

OK - agreed, that there is no mention now of skilled and instructed persons - I was just trying to get the OP to think about the risk hierarchy that he is trying to address with the design given the supply is a part of a life safety system


If the fire alarm supply cable is buried in zone, then is there a very real, credible risk of a "strike" to that cable in this environment - I suspect not


It may well be that the selected cable is already compliant in terms of an earthed metallic screen or sheath - it may take some calculations to prove that


It is a requirement for a lockable isolation position so it seems entirely credible to me that the 230V supply cable would easily be installed in a length of earthed conduit from the ceiling void to the lockable isolator and then to the panel, as a flush installation


Personally, I would try to avoid at all cost the provision of RCD protection to this circuit from a life safety safety perspective.


BS 7671 excludes fire alarm systems compliant with BS 5839-1 - is the 230V feed to the panel actually a 230V fire alarm circuit ? -  and not covered by BS 7671 anyway.


Regards


OMS