Pacific Gas & Electric has issued its annual plea for the public to use extra care in handling helium-filled metallic balloons common to Valentine's Day, saying lost balloons caused 290 power outages in Northern and Central California last year.

The shiny balloons can cause a short circuit when they come into contact with energized power lines and in 2012 cut power to 134,000 customers just in the northern half of the state, PG&E said.

The incidence of outages caused by metallic balloons has more than doubled in the past decade, PG&E said.

Anyone possessing the balloons is asked to keep them indoors, use weights to keep them near ground level or keep them tethered to avoid a problem.

If a balloon does become tangled in a power line, it is dangerous to try to retrieve it, PG&E said.

Any such situation should be reported to PG&E at 1-800-743-5000.