The Science Behind Balloon-Caused Outages

Boquet of balloons near power linesOn a hot summer day, you’re barbecuing in the backyard to celebrate a birthday with family and friends. The yard is filled with great food, crepe decorations, and birthday balloons. In good spirits, your friend hands a shiny metallic balloon to your young nephew, who promptly releases the balloon into the sky.

As you look up, the balloon quickly approaches a power line just above the backyard. The balloon makes contact. Suddenly, there is a flash, with sparks shooting in every direction, and the power goes out throughout the neighborhood.

Why does this happen? The shiny balloon is made of a material called Mylar. While Mylar is a nonconductive plastic, the external coating of this type of balloon contains metal, making it a conductor of electricity. When the balloon’s conductive coating hits the active electrical line, this creates a momentary spike in electricity and short‑circuits the power line, resulting in potential outages, fires, and damage to equipment. The explosive reaction often resembles this clip of a Mylar balloon hitting a power line in Long Beach, California.

In addition to its dangerous coating, a Mylar balloon is also more likely to run into a power line than any other type of balloon, such as a latex balloon. The metal coating makes the balloon airtight, preventing the helium from escaping through the material and allowing the balloon to stay inflated for up to two weeks longer than other balloons. This significantly increases the chances of power line contact. While any helium balloon can create damage from hitting an electrical line, Mylar balloons tend to be the worst.

To avoid unnecessary power outages, damage, and injuries, follow these precautionary steps when celebrating with helium balloons:

  • Keep balloons indoors when possible
  • Tie down balloons with a weight
  • Never release balloons outside
  • Puncture balloons before disposing of them

If you see a balloon stuck in a power line, don’t try to remove it or touch the power equipment. Call our Utility Control Center at (408) 615-5640 for assistance.