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Occupational safety course.doc
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4.1.1. Lightning-proof installation

Lightning-proof and protection from atmospheric electric is ensured by:

  • installing lightning-rod;

  • installing metallic grounded cells around outside objects;

  • grounding facilities inside the building;

  • making electric connection among close metallic elements of the building, such as pipelines, and grounding them.

Protection from lightning stroke is made with separate lightning-rods or ropes set on building.

Lightning-rods are selected in accordance to building’s plan. Lightning-rods of objects referred to category I are not set on the building however they should have dielectric stand 8 m above the building, grounding resistance up to 10 ohm and be situated 8 m as nearest. Grounding resistance is to be 20 ohm as maximum in category III .

To protect buildings and structures referred to categories II and III from lightning stroke lightning-rods are set separately or on the building as not insolated rods and ropes, or as metallic cell made from wire of 6-8 mm in diameter.

Connecting nearly situated metallic components of building, such as pipelines, in the places where less 10 cm is between them along every 20 - 25 m prevents electric induction. Resistance of that connection should be 0.03 ohm as maximum.

Grounding metallic parts of communication and other systems prevents transferring high electric potential inside building.

4.2. Fire safety systems

4.2.1. Fire safety

Variety of technological processes and occupational objects poses many methods for fire prevention. Fire safety of areas with computer terminals is maintained by Fire Safety Rules in Ukraine “DNAOP 0.00-1.31-99” and other standards.

Buildings and their areas equipped with computers should have second degree of fire resistance as minimum. Neighboring areas can’t be referred to A and B category of fire and explosion risk. B category areas should be isolated from areas with computers by fire resistant walls.

Fire rated floors in computer areas is made from incombustible materials (or hard-combustible ones with fire resistance 30 min as minimum). Space under detachable floor is separated with incombustible supports. Fire resistance lower limit of the supports is 75 min. Communication cables are mounted through the supports in special rings using incombustible seal to prevent spreading fire from one area into another.

Soundproof equipment is also made from incombustible or hard-combustible material.

Areas equipped with computers should have automatic fire alarm system with smoke detectors and manual fire extinguishers in quantity 2 units for each 20 m2 of the total floor area what considers limits of acceptable concentration of extinguishing substance also.

Cables situated under the floor should be cleaned from dust quarterly at least.

4.2.2. Automatic fire detectors installing.

Automatic fire detectors are mounted all over the work area to cover all fire dangerous zones. Point fire detectors are recommended to instal in the area using scheme of triangle or square locating.

Detectors are mounted under cover. In exceptional cases it’s allowed to set them on the wall, beam, column, or hang on the rope also.

Inside the area having width up to 3 m the distance between smoke point detectors is allowed to increase up to 15 m along the length, besides first and last detectors should be distanced from the wall at least at 7.5 m.

Inside the area of height over 8 m linear detectors are set in two rows.

Maximal and maximal-differential heat detectors are activated by temperature from at least 20С up to 70C over maximal acceptable air temperature. Maximal distance from source radiating heat (incandescent lamp etc) to detector makes 0.5 m.

Fire detectors are mounted under cover, on the walls or another construction components of the building. Detection angle, maximal detection distance and controlled area of one detector shouldn’t exceed values established in its technical documents.

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