An experienced metering technician received medical attention and underwent retinal and cardiac assessments after an arc flash incident.

The technician, working for Spotless, was completing a CT validation and was re-inserting B-phase potential fuse wedge into the fuse holder when a phase-to-phase arc flash occurred.

Spotless released an incident report to highlight the issue and help prevent similar incidents occurring again.

The arc flash incident

An investigation found the three potential fuse holders inside the metal CT Chamber had been installed on a metal mounting plate.

The line side wire passed through this metal mounting plate into the rear of the fuse holder.

 

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The line side wire had not bee completely inserted into the terminal of the B-phase fuse folder. This left the bare copper wire exposed.

As the potential fuse wedge was re-inserted into the fuse holder the copper wire connected with the metal mounting plate, causing a phase-to-phase arc flash. The flash caused all three potential fuses to blow.

A pre-inspection of the terminals of the three potential fuses was not possible due to a clear Perspex cover that had been installed.

What had to be done

The metering technician required medical attention and had to undergo assessment to his eyes and heart.

An immediate “change to work procedure” was then issued to all currently engaged metering technicians to visually check CT Chamber prior to commencing work.

Work is to be aborted if the visual check confirmed potential fuses installed on a metal mounting plate with wires inserted through and into rear terminals of fuse.