Section 50.63. Unit systems

(a) Limitations. Unit battery systems shall provide the required intensity of illumination for a minimum period of 1 hour.

(b) Cabinet design. Emergency lighting units of this class shall be compact and self-contained. Batteries, relays, charging equipment and controls shall be assembled in a substantial metal cabinet. The cabinet shall be well ventilated and designed so that the equipment can be easily maintained. The emergency lighting load shall be connected automatically to the battery in the event of power failure.

(c) Type of batteries. Lead acid batteries shall be the glass jar or the heat resistant plastic jar type or other approved types assembled with 1.200-1.225 specific gravity, full charge electrolyte. At least one pilot cell shall contain a suitable means for indicating the approximate state of charge, which shall be visible from outside the unit case. Other types of batteries may be approved.

(d) Battery charger. Units shall contain a suitable dry disc type of charger capable of charging the battery at a high rate and also at a suitable maintenance of trickle rate. The high rate charge shall be capable of replacing the maximum charge taken out in 1 hour emergency discharge period within 12 hours. The unit shall be designed to provide for automatic high rate charging and restoration to trickle rate. After power failure or when the battery becomes discharged so that the unit cannot provide 1 hour of illumination of required intensity, the battery shall be charged at a high rate, until it becomes fully charged at which time the charging rate shall be reduced to the trickle rate. No device which could render the charger ineffective shall be permitted.

(e) Test switch. All units shall be equipped with a suitable test switch mounted outside of the cabinet and connected to simulate a power failure to the unit.

(f) Signals. All units shall be equipped with a visual signal to indicate when the battery is being charged at the high rate. Units equipped with a switch to disconnect the emergency lamp load in the event of power failure when the building is not occupied shall have a visual signal to indicate when the switch is in the normal position and the equipment is ready to provide emergency lighting.

(g) Wiring and mounting. All units and lamps connected remote from the units shall be permanently mounted. Units shall be mounted so that they may be readily tested, inspected, and serviced and shall be maintained in satisfactory working condition. When remote lamps are used, wiring shall be of sufficient diameter to provide not less than the minimum required illumination. No switch shall be used to cut off the remote lamps.

(h) Hydrometer. A hydrometer shall be available, and the batteries shall be tested with the hydrometer at least once every month. A record of tests shall be maintained and shall be available for inspection.

(i) Nameplate. The nameplate required by § 50.61(g) (relating to general requirements) shall also contain the capacity of the system in watts, rated nominal voltage and current.