“IEC regulation 20-105V1 “Fire-resistant electrical wires, which do not spread the flame, without halogens, with nominal 100/100V tension, for application in fixed automatic fire detection systems and fire alarm alerts” and the planning standard UNI 9795:2013” Automatic fire detection and fire alarm systems – Design, installation and operation”
The designer’s obligation to observe certain transmission parameters in order to prevent malfunctions is clearly identified.
This obligation is often ignored and not observed, causing the designer and the installer to have to intervene both legally and economically in the event of malfunctions with the fire detection and alarm system.
The reason for this regulatory requirement can be found in the technological evolution and consequential migration of systems from conventional (in other words, analogue) to addressable (in other words, digital) systems.
This technical migration has brought about the need to adapt the interconnecting wires to the actual performance of the equipment with the aim of ensuring protocol is passed on correctly.
Technical specifications where the interconnection line is only assigned the indication EN50200 standard lines expose the designer to possible disputes, already in the design phase, as the indication provided is incomplete, not valid and incorrect.
The importance of passing on the correct information
The communication guidelines ensure the exchange of short sequences of information called posts or frames through BUS stations. They contain commands, checks or measures which can be interpreted by each device placed on the loop or on the line.
All the devices, linked to the means of communication in simple derivation, are normally in a receiving state, ready to decode messages sent to them.
An appropriate control mechanism, created in each device, is able to avoid collisions by preventing the occurrence or by resolving events when they are about to occur.
Identification of the recipient of the message happens through recognition of the address which is a mandatory part of each message.
This identification takes place by setting the device’s unique address.
It can take place through physical setting through various components, for example: DIP switch, Rotary DIP switch, through programming of the address via external devices,… or through automatic settings called auto-configuration.
The term BUS system generally indicates the set of all the devices connected to the same and only communication support (for example, CAM BUS) where there is a real exchange of digital data between the various devices (for example: functional monitoring, detected temperatures, optical chamber cleanliness level, activation commands, device polling,…).
Obviously, in a fire as well (test methodology IEC EN 50200) the wires must be able to ensure the circuit’s integrity, maintaining their functionality.
Within the fire detection system 3 types of main lines can be identified:
For connection of devices with operating voltage equal to or lower than 100 Vac (for example sensors, manual pull stations, interfaces, voice evacuation systems, optical-acoustic sounders, smoke heat evacuation systems, etc.) the use of fire resistant cables is required subjected to testing in compliance with CEI EN 50200 (minimum requirement PH 30) with rated voltage of 100 V (Uo/U = 100/100V) and constructed in compliance with CEI 20-105 V1.
There are two versions of this first type, the one for interconnection of fire detection system and the one for EVAC systems:
- There are two versions of this first type, the one for interconnection of fire detection system and the one for EVAC systems:
- They must be suitable for installation together with electric cables used for systems with rated voltage to ground up to 400V
- Cables for smoke detection systems (operating voltage ≤100V external sheath colour red) ….
- Cables for voice systems with 70Vac or 100Vac lines (RMS value) rated, (external sheath colour violet, for example: EVAC
Both types must be LSZH with a PH 30 minimum requirement and in any case, in the event of two separate zones or compartments, no lower in order to guarantee maintaining operation for a period no less than that required by specific fire prevention technical regulations.
For connection of devices with voltage greater than 100 Vac the use of fire resistant cables is required subjected to tests in compliance with CEI EN 50200, but unlike those mentioned above, the construction characteristics must comply with CEI 20-45 – Uo/U=0,6/1 kV….. for example: FRH
