Mylar balloon causes transformer explosion in Huntington Beach

What happened

A Mylar balloon became tangled in a power line in Huntington Beach, California, causing a transformer at 6371 Down Drive to explode at about 12:13 p.m. The event produced a loud popping sound and a big spark, which prompted a flood of calls from nearby residents. Some wires came down and Southern California Edison crews were called to the site. Nearly 2,800 customers were initially without power. By 1:30 p.m. the utility said this had fallen to 161 customers, with power expected to be restored within the hour.

At about 1:30 p.m. fire officials said the outage in the immediate area could last five hours. The outage boundaries were Melbourne Drive, Windemeir Lane, Ventura Drive and Countess Drive. No injuries were reported.

Contributing factors

A Mylar balloon contacted an energised power line. The source notes that the silver metallic coating on Mylar balloons conducts electricity, which is why they must be kept away from power lines.

Lessons learned

1. Metallised balloons can bridge energised conductors and cause transformer faults, so exposed overhead lines and their surroundings should be treated as a known hazard.
2. Utilities and fire services should give public and event organisers clear guidance on keeping balloons away from power lines.
3. Restoration estimates from utilities and fire agencies should be reconciled and communicated consistently, as the estimates here differed markedly (one hour against five hours).

More lessons on design, standards and commissioning, fire suppression and firefighting, from every incident on the register.

Source

patch.com