Several factors could have triggered fire in manhole which caused downtown outage

HONOLULU (KHON2) — An electrical engineer says several factors could have played a role in causing the fire that led to Monday night’s outage.

Although the cause of the fire is still unknown, there could be a few reasons why the fire started.

“Electrical fires are are not uncommon,” said Steve Durbin, UH Manoa Associate Dean of Engineering. “And when you’re running high voltage transmission lines, especially underground, it’s one of the things that you have to prepare for.”

Durbin said putting more demand on our infrastructure could be a cause too.

“As population increases, and as it gets warmer, and your air conditioners are used more, as we look to recharge electric vehicles, we just put more and more demands on the existing electrical infrastructure,” he said.

“Anytime you have a connection or a disconnection, something switches on and off so you can generate sparks and sparks are easy to generate with high voltages,” he added. “Again, we use high voltage and transmission so that we can use smaller wire carry lower current so it’s safer from that perspective.”

When it comes to having underground lines there are pros and cons. He said having underground cables are good when it comes to safety and high winds, but access is very limited.

“You can’t just walk along the transmission line until you see something that obviously looks like it failed,” Durbin explained. “You have to generally pull through it or send some cameras down, and that takes time.

He said it’s not an easy fix either, which is why the repairs can take so long.

He said other areas with underground lines around the same age could fail too, but it’s difficult to balance a time to do maintenance or repair something not already broken.

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“But doing a lot of replacement for electricity generally means taking the power grid down temporarily, and that’s usually not very popular,” he added. “If we proactively go through and replace everything we can as often as we can, that cost would have to be borne by the customer, and then we’d be upset that we’re spending so much money replacing things that were still good. So it’s just a delicate balancing act.”