Section 50.62. Storage battery systems

(a) Types of batteries permitted. When lead acid storage batteries are provided as the emergency source of supply, they shall be designed and constructed to adequately meet the requirements of emergency lighting service and shall be contained in sealed glass or heat resistant plastic jars except as otherwise noted in this chapter. The cells shall be assembled with an electrolyte having full charge specific gravity of 1.200-1.225.

(b) Battery charging equipment. Storage battery emergency lighting systems shall be equipped with a device for maintaining the batteries in a fully charged condition. No switch which may render thisdevice ineffective is permitted. Each time the emergency lighting system is used because of the failure of the main supply, a charge at maximum rate shall be given to the battery immediately. The same rate of charge shall be given to the battery as often as necessary to assure its maintenance in a fully charged condition. The charging device shall be capable of placing the batteries in a state of full charge with 12 hours after restoration of power following a power failure.

(c) Care of batteries. Storage batteries used in emergency lighting systems shall be mounted in a well ventilated room or cabinet, and will be maintained at a temperature of not less than 65° F. The mounting of the cells shall be of ample strength and rigidity to carry the weight without appreciable sagging. Batteries shall not be located in places where they would be subject to deterioration through dampness.

(d) Voltmeter required. Storage battery systems shall be provided with a voltmeter having a guaranteed accuracy of 1% of full scale, except that a voltmeter having a guaranteed accuracy of 2% of full scale may be used if the voltmeter received a special calibration at the normal float charge value so that the accuracy of indication at this point on the scale is not less than 1.0% of full scale value. The voltmeter shall indicate the voltage of the battery at all times.

(e) Nameplate. The nameplate required by § 50.61 (g) (relating to general requirements) shall also contain the final rated voltage of the battery under load at the end of the one hour period, the specific gravity of the electrolyte when the batteries are fully charged, capacity of system in watts, rated nominal voltage and current.

(f) Capacity. The capacity of the storage battery when fully charged shall be sufficient to carry the connected emergency load for a period of not less than 1 hour with a final voltage not less than 87% of the nominal lamp voltage.

(g) Trouble indications. Storage battery systems shall be provided with a device that gives an audible and visual signal when there is an open circuit between the trickle charger and the battery. Such signals shall be located so that they may be seen and heard by a responsible person. In place of the signals the voltmeter required in subsection (d) shall have plainly marked zones as follows:

(i) A marked zone to indicate proper trickle (float) charge voltage.

(ii) A marked zone to indicate a failure of the trickle charger or that the battery is discharging into the emergency lighting circuit.

(iii) A marked zone to indicate during normal float charge operation that there is an open circuit between the trickle charger and battery.

(h) Hydrometer. The manufacturer of storage battery emergency lighting systems shall supply with each device a hydrometer and directions for its use in order that the owner may be in a position to test the specific gravity of the electrolyte. Such a test shall be made at least once every 2 weeks, a record of test shall be maintained and shall be available for inspection.

(i) Other use of batteries. The batteries of emergency lighting systems may not be used for any other purpose unless approved by the Department.

(j) Modified low voltage systems. Battery operated emergency lighting systems, not less than 12 volts or more than 24 volts may be used with the special approval of the Department when the emergency lighting illumination required does not necessitate a battery capacity in excess of 250 watts at the rated voltage for a period of 1 hour.