Electric Shocks

What did the reporters tell us?

The first report concerned an auxiliary feed water pump starter panel. An alarm sounded, indicating a trip, followed by a fire alarm; smoke was coming from the panel. Although there was no fire, the thermal relay unit and the electrical cables were burnt. No injury was incurred, thanks to insulated rubber gloves being worn. The cause was use of a metallic brush part of which touched two live wires. There was no daily job meeting, meaning there was no opportunity to assess the risks.

The second case concerned a diesel generator tripping out on a cooling water temperature alarm. The stand-by generator started automatically; electrical power was restored. Subsequent investigation revealed that cable insulation had peeled off; two cables then made contact, leading to a short-circuit. Following the repair, all other generators were inspected and several damaged cables were identified that required immediate attention

The lessons to be learnt

In the first case, Insulated gloves saved the engineer from injury. However several necessary measures were lacking (see below).

In the second case, the stand-by generator started automatically; power was restored. However the inspection and maintenance of cabling beforehand was below standard.

CHIRP Suggests

Electricity can be a killer; working with it demands the utmost respect. A risk assessment, electrical permit to work, isolation of the equipment by tagging or locking out, a toolbox talk and proper supervision should have been in place and would have mitigated all risks. The UKCOSWP 2015 chapter 14 refers.

Electrical cables should be inspected periodically. The inspection of generators is routinely covered by planned maintenance   schedules.

However are procedures intelligently followed with the right supervision and training? Or do we blindly follow the worksheet (ticking boxes)? This is a continuously recurring theme.