Background
When considering the hazards associated with electricity there can be a tendency to focus on mains power (alternating current) rather than on the batteries used to start-up, protect or maintain the operation of plant and equipment. For example, battery banks in substations, uninterruptible power supplies (UPS), or equipment power packs.
Recent inspections by the department have raised concerns that the hazards associated with batteries are not always recognised or adequately controlled. There have also been reported incidents involving batteries that resulted in injury, the potential for serious injury, or damage to equipment.
Examples in the past 5 years include:
- two separate instances where electricians received arc flash burns to their hands after incorrectly reconnecting batteries in a UPS
- an apprentice electrician received burns to his fingers after incorrectly inserting multimeter test leads inside a UPS and causing a short circuit
- a worker fault-finding on a vehicle received burns to his wrist when the metal band of his watch caused a short circuit between the battery’s positive terminal and the vehicle chassis
- two batteries at a fire pump exploded, sending fragments several metres away (no one was in the vicinity at the time).
Summary of hazard
The hazards associated with batteries mainly relate to their use, configuration and storage design.
- If the stored energy in a battery is released in an uncontrolled manner (e.g. short circuit), the electric current can cause an arc flash, extreme heat or fire, which can result in thermal burns.
- Many battery chemicals are corrosive and/or poisonous. If these leak, it can harm workers or damage equipment.
- Batteries can burst or explode due to the build-up of gases through excessive recharging, overcharging or short-circuits, leading to chemical burns or shrapnel injuries.
- When batteries are connected in series, the increased voltage between the end terminals can be enough to cause electric shock if touched.
Contributory factors
Incidents involving batteries usually happen when the risk controls are inadequate. Examples are listed below.
- Battery cabinet design not preventing inadvertent contact or providing adequate ventilation.
- Ineffective training and supervision of workers working on batteries and UPS systems.
- Incorrect isolation or not applying suitable barriers or clearances before working on equipment.
- Risk assessment inadequate for the work to be carried out.
- Work performed outside of the required safe system of work (procedure or instruction).
- Inadequate maintenance, test and repair program for batteries and UPS systems.
- Workers using uninsulated tools and not wearing appropriate personal protective equipment.