FSIB have run successive newsletters from 2012, 2014, 2016, 2020 regarding cables and cable installations but some contractors continually bend the rules and subject a new installation to false and nuisance alarms, it is time to issue another reminder.
Fire detection cabling is the backbone of the fire detection system and if not installed correctly can be the cause of numerous system problems.
Fire detection cables are either PH30 able to resist the effects of fire for 30 minutes or PH120 able to resist the effects of fire for up to 2 hours. Cables are generally red in colour to identify them as fire cables.
Cables can be run around the building in steel conduit, steel trunking, steel cable racks, in PVC conduit with fire resistant supports or in the open. Whichever method is chosen it must be supported securely so that it will not collapse or fall to the floor in a fire condition.
Addressable systems call for cables to be installed in A-Class configuration, that is cables must be run out of the panel in one direction and return to the fire panel from another direction. This is to ensure that communication to all the fire detection devices can be conducted from either direction.
By keeping the two legs clear of each other by using different routes means there is less chance of both cables being cut or damaged at the same time.
Separate from other services
Fire detection cables must be run separately from other building services, they must occupy their own conduits or trunking and not be shared with security cables, evacuation system cables or mains cables etc.
Fire alarm cables should not be run alongside mains power cables. If this is unavoidable the distance must be restricted to about 30 m.
Earthing and shielding of cables
Within PH30 and PH120 cables the conductors are fitted with a screen covering and drain wire. It is essential that this screen is connected to the building earth to shield it from interference from other services. One end of the cable is connected to the earth of the fire panel, and it must be terminated at every detector on that circuit up until the return leg enters the fire panel again where it is cut off and allowed to “float”.
Cables must be kept clear of power cables as far as is practical.
In some cases it might be cost effective to run a multicore cable in the building and take off pairs of wires where needed. This must not be considered and is a non-compliant issue in accordance with the national standard. If this cable is cut it can disconnect more than one circuit or area of the building.
Joints in cable
Fire alarm cables should never be joined unless inside of a detection device or the fire panel. Cables should be withdrawn, and another cable pulled in its place. If there are no other options, the cable must be joined in termination terminals inside a housing marked “Fire alarm system”.
Cables are the backbone of every system, do it properly the first time will prevent the need to return to site to deal with unforeseen problems.
Every year the FSIB issue “Inspector of the year awards” to companies and individuals that in the inspector’s opinion have excelled during that particular year.
The 2021 awards were all won by one company, MULTINET SYSTEMS of Pretoria.
The inspector witnessed a change in company presentation, contribution to the industry as a whole and big improvement in the quality of their work.
Multinet Systems were awarded the following:
Company of year
Most consistent quality work award
Best technical team award