Automatic Circuit Reclosers Probed as Potential Cause of California Fires – IEEE Spectrum

https://spectrum.ieee.org/energywise/energy/the-smarter-grid/utilities-probed-as-potential-cause-of-california-fires

Automatic reclosers are pole-mounted circuit breakers that can quickly restore power after outages. Reclosers make quick work of many line faults, the great majority of which result from temporary insults such as a tree branch striking a line or the electrocution of an unlucky squirrel. Reclosers usually try restarting a line 2-3 times before giving up and “locking out” a line. 

Reclosers solve many problems automatically and quickly, but they have also one potential disadvantage: they can increase fire risk from damaged lines. During restarting high-temperature electrical arcing often happens at the site of the fault. It can burn away hung trees or tree limbs, and sometimes spark a fire. 

It is estimated that reclosers have had their part in Australia’s deadly Black Saturday bushfires in 2009 and fires in California in recent months.