The Day I Melted a Switchboard

THE DAY I MELTED A SWITCHBOARD

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The company I was working for was wiring a towering skyscraper in the centre of Auckland CBD.

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At the time, I was still an apprentice electrician.
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I was a decent apprentice through, well known for my meticulous approach to every task.

I took pride in the precision and neatness of each of my installations

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This week my assignment was to install a builder's temporary supply,

a lifeline that would power the construction site from the ground up.

How it works:

- We place a large electrical box on each level of the building, 30 in total.

- The boxes have a dozen or so power outlets on their sides for tradespeople to use.

- A thick cable then runs between each floor, looping each box together like a long, vertical daisy chain.

On that fateful day, I was connecting the first box to the main switchboard supply in the basement.

I meticulously terminated the cable into the circuit breaker and conducted all necessary safety tests - twice.

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True to my nature, I wanted to ensure everything was perfectly organised and secure before switching anything on.

After testing, I noticed that the large cable looked slightly out of alignment,

so I pulled a cable tie tighter, striving for that clean, professional look.

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With a final visual check over the system, I was fully confident in the precision of my setup and test results.

The switchboard was mounted on the floor, so I bent over and flipped the 1000 Amp circuit breaker ON to energise the system.

Instead of the quick 'snap' of the circuit breaker, a deafening boom and a blinding explosion erupted right before my eyes.

I saw in front of me a giant white orb - about the size of a basketball - appear for a microsecond,

accompanied by an enormous low boom, felt through my bones.

The force of the blast knocked me back against another switchboard behind me.

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For what felt like an eternity, my world was nothing but a bright, disorienting white.

My ears rang painfully loud, drowning out everything else,

Like how they depict a shell blast in war movies.

The shock overwhelmed me, rendering me frozen as I tried to process what had just happened


What went wrong?

When I pulled the cable tie to straighten the cable, the sharp edge of a steel backing plate had penetrated the outer cable layer,

Just enough to touch the copper conductor inside.

Fortunately, an upstream circuit breaker had done its job properly,

Switching off power to 1/3 of the tower - preventing any further danger.

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The loud boom had travelled through the lower floor basement.

Co-workers quickly rushed in from various locations to help, removing me from the main switchboard room.

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Afterwards, we learned that workers on the upper levels of the building had also heard and felt the blast.

After the shock wore off, I noticed small burn marks all over my safety vest and pockmarks embedded into my safety glasses

Silent witnesses to the molten copper from the explosion.

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The switchboard was black with carbon from the arc flash,

and a large chunk of the solid steel plate had vaporised.

The incident was not just a scare but a profound learning experience.

It reinforced the importance of vigilance when working with power,

contributing to my respect for the immense amount of potential energy we deal with daily.

Reflecting on that day, I am so grateful for the safety protocols that had been drilled into us

Especially the strict adherence to personal protective equipment (safety glasses and cotton long sleeves in particular).

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These electrical safety measures allowed me to walk away from that event with nothing more than a valuable lesson.

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