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INDOORPLANT

RADIO TRANSMITTING AND RECEIVING SAFETY REQUIREMENTS

5.2.1 Fixed Station (Point-to-Point; television, FM & AM Radio; Space Communication)This section covers radio transmitting and receiving stations at fixed locations used for point-to-point overload or space communications and video, AM and FM transmissions.

A. Fixed radio station building is not to be struck directly by lightning because of the shielding effect provided by the antenna tower/s. However coaxial cables and high frequency antenna transmission lines can conduct hazardous currents into building. The grounding system shall be designed to reduce the earth potential gradients around the station building.

B. Radio site protection involves special consideration because direct lightning hits are usually expected. The protection plan shall be very carefully engineered, maintained in order to hold differences of potential between various parts of the station to safe values.

C. For solid state component protection, low voltage protection devices shall be used and because low voltage protection devices have limited surge capability themselves, several stages of protection may be employed.

D. Most electronics and communication equipment installation require A.C. power for certain components. Shall necessitate protection considerations to prevent damage to equipment connected to such lines.

E. The earth electrode shall be a combination of made electrode specified in rule 3.2.4C. The ground resistance shall not be greater than 5.0 ohms at all times as measured by the fall of potential method as specified in rule 3.4.1 B. The minimum wire size specified in table 5-1 is for electrical protection consideration only and if the system design calls for portions of the grounding system network to carry operating currents, the conductor size shall be increased correspondingly.

5.2.2 Mobile Station (Land Mobile; Maritime mobile; Aeromobile)Covers radio transmitters, receivers, transceivers and allied equipment at mobile locations;

Land Mobile2. Maritime Mobile3. AeromobileInstallations of transceivers, handsets, control panels, microphones, loudspeakers, shall not increase the risk of injury of the driver or pilot and passenger in case of accident or collision.Battery cables shall have insulation strength rating of not less than 10 times the maximum voltage to which it is to be connected and adequate mechanical strength to withstand the expected abrasion; exposure to dirt, heat (150 C), humidity and the extreme environmental conditions mobile installations encounter.Electronic and communication installations in larger water craft or trains are mostly powered from normal A.C. supply and in such cases, rules in this code to meet general rule 5.1.1 apply. Cables used for watercraft installations shall be those approved for marine application.

5.3 SWITCHING EQUIPMENT SAFETY REQUIREMENTS (Telephone, Telegraph, Telex)

This section covers equipment installation employed for selective interconnection of channels of communication using electro mechanical and/or electronic circuit elements to perform the function.

5.3.1 Switching materials is subjected to damage from lightning and power fault currents which may conducted from outside plant cable. For protection for the user and the equipment these foreign potential surges shall be effectively limited by application of suitable protective devices.

5.3.2. Surge arresters of suitable type and rating shall be connected on all wire circuit entering the building except on wire lines meeting all of the following criteria:

The entire length is underground;Not bunched with a circuit any portion of which is installed above ground level;Not bridged to any wire circuit that may be exposed to foreign potential by contact or induction.

5.3.3. Depending on the desired protection level adopted, arresters should be fitted on power services serving the station.

5.3.4. The switching office earth electrode shall be any or a combination of made electrodes specified in Rule 3.2.4 C. The ground resistance shall be 5.0 ohms or less at all times.

5.3.5 The earth electrodes shall be bonded to the following:

Continuous buried metallic public water pipe system;Continuous buried metallic private water pipe system with at least 3.0 meters of buried pipe; Deep well metal casing.

5.3.6. Connections to earth electrodes shall be made using methods and clamps acceptable to the entity enforcing this code.

5.3.7. For big offices, a ground bar shall be used, connected to the earth electrodes. For small offices ground bar may be omitted and grounding conductor connected to earth electrode, on one end and running the full length of the equipment line-up , where equipment rack/s shall be bonded.

5.3.8. Ground conductor sizes, shall be in accordance with Table 5-1.

5.3.9. Insulation of all cables shall be polyvinyl-chloride (PVC) or equivalent formulation with equal or better resistance to burning.

5.3.10. Office furniture required in the operations should be of metal construction or other non-combustible material contents.

5.3.11. Stationary and other office and maintenance supply shall be stored in areas external to the switching rooms. It shall be prohibited to store combustible materials in transformer vaults, switch gear rooms and power distribution