The Mine Safety and Health Administration has issued an electrical safety alert after several miners were injured in underground coalmine accidents.
In one incident, a miner working near a 480 VAC scoop charger circuit breaker received flash burns to his eyes. In another incident, while a miner was repositioning a 575 VAC permissible water pump, he grabbed the pump cable and received an electrical shock. In a third incident, when a mine foreman attempted to pull a roof bolter trailing cable out from under a rock fall, he received an electrical shock. Finally, when an electrician contacted an energized component in the control panel of a 995 VAC continuous mining machine, a miner was shocked.
The mine safety agency’s recommended best practices include:
- Do not perform any electrical work until a circuit is de-energized, locked, and tagged out, remembering that “electrical work” is installing or maintaining electrical equipment or conductors.
- Be knowledgeable of the hazards of electricity, never touching any ungrounded electrical component until you are sure it is de-energized.
- Identify all hazards and then develop and follow a safe plan to perform work or troubleshoot to protect the safety of all miners. Always de-energize equipment, except when it is necessary for troubleshooting or testing.
- Always handle de-energized cable instead of energized cable or wear properly rated and well-maintained electrical gloves when handling energized cables.
- Protect electrical cables from damage by mobile equipment and falling roof. When cable damage is suspected, immediately notify a qualified electrician so a potentially dangerous condition can be corrected.
- Install sensitive ground fault relays with instantaneous trip setting of 125 mA or less on all face equipment. Use trailing cables with a grounded metallic shield.
- Wear properly rated personal protective equipment (PPE) to protect against Electrical Shock, Arc Blast, and Arc Flash by following the National Fire Protection Association (NFPA) 70E Standard for Electrical Safety in the Workplace.