Ask an Expert: What's a Cable Fault?

When the lights go out unexpectedly, everyone wants to know: what happened?

There are many causes of power outages, with weather and cable faults being, by far, the two most common.

So what exactly is a "cable fault"? We asked Cableman Jeff.

What's a cable fault?

A cable fault is when the insulation of a power cable deteriorates enough that it's no longer able to contain the voltage, causing a short.

Basically, it's a hole, or a crack, burning through the cable.

Check out what a cable fault looks like. Click on the images above.

What causes a cable fault?

• Moisture, grit and/or contamination make a crack in the cable insulation, and the crack gradually grows close enough to the core to create a short
• Normal aging
• Accelerated aging (e.g. due to environmental stresses), which may lead to issues such as overheating
• Corrosion of the cable-protected insulation
• Degradation of the cable insulation
• Third-party damage (e.g. someone damaging a cable during excavation work)

How do we find cable faults?

Faults are easily identifiable on aerial wires, but what about on cables buried three feet underground?

A two-man crew uses a special vehicle — the only one in the EPCOR fleet — called a fault locator truck (a.k.a. the "thumper truck") to pinpoint where a cable fault is underground.