¡§Recent accident investigations and inspections revealed that an improperly maintained switch may result in arc interrupter blades that do not fully open from the arc chute and would still conduct current,¡¨ the agency said, adding that compliance to regulations effects not only the operation of equipment, but also the workers counting on the disconnection.
Not properly maintaining switches, MSHA added, can create a situation were an arc interrupter blade will not fully open from an arc chute ¡V this means that, with the handle in the open position, that current can still be conducted.
It recommends a series of best practices for mines to consider for both equipment condition and miner safety. They include:
High voltage switch gear should only be operated by qualified electricians who have received thorough training on the disconnecting switch being used;
Always wear suitable high voltage Personal Protective Equipment (PPE), such as electrical gloves, while operating such devices;
Ensure that the main and arcing contacts have visually separated, and the circuit has been properly frame grounded before electrical work begins on the isolated electrical circuit;
Follow the manufacturer¡¦s maintenance schedule program for each electrical device; and
Review and establish regularly scheduled maintenance procedures to ensure that the proper service has taken place.
