PG&E power line sensor upgrades may be too sensitive, resulting in shutoffs

In an effort to keep reducing wildfire ignitions, Pacific Gas & Electric has upgraded sensors that can tell it more quickly if a power line has been compromised or might spark a fire. But some of that technology, which has set off some false alarms, has resulted in unnecessary localized shutoffs. It is an evolving work in progress where a unnecessary shut off is far better than the alternative.

Of some 25,000 miles of power lines that deliver you energy, PG&E has determined that 10,000 miles are in the highest High Fire Threat zones. On those lines, PG&E has strategically placed automatic sensors that will shut power off if it shorts out. 

"If something were to touch the line, it shuts off automatically and it doesn't provide a spark. So, it prevents a wildfire," said PG&E Spokesperson Deanna Contreras.

Lightning, animal contact, a branch leaning against the power line or a complete break from a falling tree or limb will cause the sensors to automatically decide if the line should be de-energized. To provide maximum safety, they have tweaked the sensors. 

"Increased the sensitivity basically, so if there's a fault detected on the line it shuts of faster and more often," said Contreras

In recent weeks, this fast trip technology caused at least five outages in the foothills mountains between Fresno and Lake Tahoe.  There have also been such outages in west Sonoma and Marin as well as Half Moon Bay and Santa Cruz. That caused some complaints. So, one of PG&E's goals is to essentially fine tune and adjust the sensitivity of each fast trip circuit breaker to match the actual wildfire risk in its area. 

"And so, we're readjusting them and recalibrating them so they're not so frequent but they are longer duration outages because these are high fire threat areas," said Contreras. Once tripped, the line cannot be energized until PG&E crews have a look at the line. "We are beefing up the patrols to restore power more quickly to finish those patrol faster and move more boots on the ground," said Contreras.

This is now crucial because California has now entered the Diablo and San Ana Wind weeks that will continue, until early rains hopefully come.