Dr.. Zzeus Q&A: Should main fire alarm insulators be double-pole insulators?


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Dr. Zzeus, Tom Brookes, MD at Zzeus Training and chair of the FSA, answers your questions regarding fire safety compliance. Q: Do fire alarm piping insulators have to be double pole insulators, and do they have to be on a residual current device (RCD)? One of the major changes in the 2017 BS5839-1 standard was the removal of the requirement for fire alarm system insulator to be a double pole insulator. So, the simple answer would be “no”. Many fire alarm technicians and engineers are not fully aware of how much BS7671 to use when installing fire alarm systems, and some are not even aware of BS7671! Paragraph 25.2 of the standard, recommending the provision of double-pole insulation, has been replaced by a recommendation to provide local and safe insulation, which does not need to be double-pole. Note 2 indicates that safe insulation is required under the Electrical at Work Regulations 1989, which means that any insulation device must provide safe insulation. BS5839-1 refers to Table 537-4 in BS7671 for the correct selection of insulation device, which in turn specifies BS EN 600669-2-4 insulation device. It also states that “many switching devices do not meet the required insulation performance standards”. Every insulator, switch and protection device that can cut off the electrical current to the fire alarm and detection system must be placed in a position where it is not accessible to unauthorized persons or protected from unauthorized operation by persons without a special instrument. Note 5: A private tool in this context is a tool that no member of the audience is likely to hold. Screws with holes will not be satisfactory, since many elements can be used as screwdrivers, “there are no flip-down valves”. Every insulator and protective device that can isolate the supply to a fire alarm and detection system, other than the main insulator of a building, shall be glued, clear and resistant to permanent fading. The main final supply circuit for all parts of the fire alarm and detection system shall be exclusively for the fire alarm and detection system and shall not operate with any other systems or equipment. The circuit(s) must be derived from a point in the building’s electrical distribution system near the building’s main insulation device. The supply must not be connected by a card, coin-operated meter or similar device. The minimum number of insulation devices must be maintained between the incoming supply of the building and the power supply of the fire detection and alarm system. In certain systems within exceptionally large buildings, where grid-connected control panels or distributed power supplies are used, the recommendation may be impractical. If, with the consent of the parties concerned, a change is adopted, whereby the main power supply for this equipment is derived from one or more local distribution panels, the quantity of insulation devices between the incoming mains supply and the local distribution panel shall be kept to a minimum. In plain English, what would you like to do? You need an insulator that can only be disconnected by a switch or a special tool that meets EN BS600669 standard, and you must have a “fire alarm”. Do not close the “OFF” label (whether it includes a protective device or not) that only serves the fire alarm circuit. What about the RCD? BS5839-1: 2017 Clause 25.2(i) A circuit providing a fire detection and fire alarm system should not be protected by an RCD unless it is necessary to comply with BS7671. Where a residual current device is essential for electrical safety, a failure of any circuit or other equipment in the building should not isolate the supply of the fire detection and fire alarm system (placed on its RCBO). Do you have a question you’d like Tom to answer? Email your inquiries to: [email protected] Additionally, get more details on Zzeus training and the range of courses on offer by clicking here


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