OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 36 Mining

Section 566 Batteries

Subsection 566(1)

Clause 5.5 of CSA Standard CAN/CSA-M421-00 (R2007), Use of Electricity in Mines, defines the safety requirements of surface storage battery rooms and battery changing stations.

“5.5.1 Location
Stationary-type storage batteries whose aggregate capacity is 5 kW at the 8 h discharge rate shall be located in storage-battery rooms or in areas with equivalent enclosures.”

Adequate ventilation is one of the most important requirements of the standard. Since charging operations generate hydrogen which is highly flammable and explosive, the area must be continuously ventilated to be safe.

Subsection 566(2)

For underground coal mine battery charging rooms, clause 6.10.4 of the CSA Standard applies and is closely followed by the Director.

“6.10.4 Storage Batteries
Storage batteries that are stationary when in use shall be located in storage-battery rooms or equivalent enclosures if the aggregate capacity at the 8 h discharge rate exceeds 5 kW, and the batteries are in unsealed jars or tanks.
Storage-battery rooms or other enclosures and battery-charging areas shall be provided with ventilation adequate to prevent the accumulation of an explosive mixture of battery gases.
Storage-battery rooms or other enclosures and battery-charging areas shall be in accordance with the applicable requirements of Clauses to, and they shall be ventilated by an intake-air split adequate to ensure the diffusion of gases discharged into the return airway.
The location for battery-charging stations shall be designated as such and shall not be used for other purposes.
The construction of the battery-charging station shall be rendered fireproof.
An air vent shall be installed at the highest part of the structure to allow any gases generated to escape into the atmosphere.
All stations shall be equipped with adequate firefighting apparatus suitable for fighting Class C fires.
Heating, if required, shall be of the forced-air type, with the heating element located outside the charging station and arranged so that fresh air shall flow over the heating element when the element is operating.
The battery-charging station shall be adequately and continuously ventilated during battery-charging operations.
Material, other than standby batteries and material required for routine battery maintenance, shall not be stored in the battery-charging station.
Electrical equipment shall either be approved or be located so as to ensure that no possibility for the ignition of hydrogen exists.
Battery-charging equipment shall be located at or near floor level and shall be permanently connected to the main power supply.
Battery-charging cables installed after January 1, 2001, shall be contained within a protective jacket having an FT5 rating as specified in CSA Standard C22.2 No. 0.3.
Battery repairs shall be permitted only after precautions have been taken to ensure the dissipation of flammable gases. Battery-charging shall be discontinued for the duration of the time taken to effect the repair.”

Air flowing into the storage room or battery charging station must come from an uncontaminated source that will not bring with it any additional flammable gases. The volume of air must be sufficient to dilute gases generated by the battery charging process. The flow of air must be directed into the return air flow so that the hydrogen gas does not flow into working areas of the mine.

An approval by the Director ensures that adequate consideration has been given to identified safety issues. The room design should include air quality monitoring and automatic power disconnects for situations where flammable gas accumulates above defined lower explosive limits.

Subsection 566(2)

Because of the potential for initiation of explosive gases, repairs to batteries must not be performed underground or in any hazardous location. A spark from a short circuited battery could be catastrophic.