Bay Area heat wave: Rising temperatures trigger power outages

SAN FRANCISCO, Calif. (KTVU) - The Bay Area heat spell could mean trouble for many sweltering neighborhoods suddenly confronted with a power outage. 

More outages are expected to continue into the afternoon and evening. 

Breakdown of Current Power Outages

• San Francisco 11 customers without power
• Peninsula 1,035
• North Bay 1,414
• East Bay 8,725
• South Bay 727
• ## Total 11,912

Pacific Gas &Electric activated all of its local emergency response centers across the entire Bay Area.

PG&E's Santa Rosa materials and equipment yard, like all such Bay Area facilities, is ready with crews, material, and equipment to respond outages. 

Monday's rolling power outages, most notably in the East Bay. 

"Yesterday it reached 104 degrees in a lot of areas. That was the highest temperature that we've seen in a couple of years actually," said Deanna Contreras, spokeswoman for the utility. "Throughout the day, about 10,000 customers were impacted; not all at once but through the day due to heat-related outages. 

Transformers of all sizes can only carry so much load. 

The problem of course whether the transformers are located up on a pole or underground. 

If they carry too much load or simply get too hot, they will shut down.

"The transformers and other equipment just can't cool down fast enough, especially the underground equipment, those in the vault, they just can't cool down," said Contreras. 

That coupled with an increased demand on the system when the weather heats up. 
"People use their air conditioners more," she said. "People use their fans more." 

Transformers step the power down from the main high voltage system to the voltage needed in homes and businesses. 

When a transform fails, it usually need to be replaced and that can take a significant amount of time for crew to climb a pole or enter a vault to swap it out.