The Energy Safety Service recently published its
summary of reported accidents.
As part of its
strategic goal to make all information available
the Board will reproduce the summary of reported
accidents that relate to registered workers and
trainees in this and future issues of ELECTRON.
The Board wishes to advise that any
conclusions relating to the accidents reported
are conclusions of the Energy Safety Service.
Accident 1
A trainee electrician working in a substation
received burns to his hands and chest when he
came in close proximity to live 11,000 bushings
on a bank of capacitors.
The trainee's task was to isolate the
capacitor bank and then examine the metalwork
for rust and carry out repairs.
The 33,000 volt section of the substation had
been isolated and the plastic covers of the
capacitors removed.
When the trainee approached the capacitor
bank to inspect it, a flashover occurred.
The trainee received burns and was found
lying on the ground.
It was later discovered that isolating the
33,000 volt section of the substation did not
isolate an 11,000 volt capacitor bank.
The company concerned reviewed its procedure
for working in substations.
Accident 2
A trainee electrician was fitting a miniature
circuit breaker for a new circuit in a
switchboard installed at a college.
The trainee had isolated the switchboard, but
when a teacher complained that the computers
were not working, the trainee restored the power
and continued working.
The trainee was having problems with the
switchboard connection not lining up with a MCB
termination and as he attempted to adjust the
connection, his pliers contacted a busbar,
causing a flashover.
The trainee received burns to his finger as a
result.
Most of the MCB rail connection block was
melted, showering blobs of copper inside the
switchboard.
The company concerned reviewed procedures for
working 'live' to ensure every effort was made
to isolate power.
Accident 3
An 11,000 volt switchboard at a major
substation was being replaced over a three-month
period.
The switchboard had been livened, the access
permit for the stage of the project having been
signed off and returned.
A trainee electrician was assigned the task
of removing temporary cables from one new
circuit breaker cabinet for transfer to another.
The trainee was working with an electrical
fitter who was to wire control and metering
circuits on the switchgear.
A second cabinet was not available for
re-termination of the cables until its metering
had been calibrated and tested by another team
still awaiting an access permit.
Once the tasks were assigned, the supervisor
proceeded to mark panels not being worked on
that day with crosses in red tape.
The trainee and the electrical fitter removed
the back cover from the second cabinet,
apparently in order to change over the cable
gland plate.
The trainee and electrical fitter may not
have realised the cable termination was live,
having been confused by the absence of a red
cross on the panel. No access permit was held
for this task.
The metering calibration team was preparing
for work in front of the cabinet when there was
an explosion in the back, and the fitter and
trainee ran outside with their clothing on fire.
Fellow workers extinguished the flames and
poured on water until emergency services
arrived. Both the trainee and the fitter had
received extensive burns, from which the trainee
died soon after.
Evidently one of the men came too close or
contacted the live 11,000 volt terminals,
initiating a flashover. The major causes of the
accident were the failure to follow the industry
safety rules regarding access permits, the use
of an informal system of marking the permit area
and poor hazard identification procedures.
Accident 4
A meter test technician was performing
calibration tests on a revenue meter when he
received an electric shock from a test lead on a
bench test unit. He was taken to hospital for
ECG tests.
The technician had forgotten to isolate the test
bench when making the connections. He was advised to
obtain registration as an electrical service
technician. Improvements to the safety of the test
room were also recommended.
Accident 5
A line mechanic received flash burns to his
eyes when he applied portable earths to a live
33,000 volt overhead line in a substation
structure.
The 33,000 volt SF6 circuit breaker was
opened and the breaker panel indicated that the
mechanism had opened but, when the line mechanic
tested the lines for isolation, he found one was
still live. He discussed the test result with a
switchroom operator, who suggested that it was
possibly induction and he should carry on and
earth the lines. As the line mechanic applied
the earths, there was an explosion and the lines
tripped. One of the contacts on the circuit
breaker was not fully open.
The company subsequently reviewed its procedures
on testing and the use of voltage detector probes,
requiring further tests to be performed when in
doubt.
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