How do birds sit safely on power lines?
We ask an expert to explain how birds manage to touch high-voltage lines
Posted by Chelsea Watt
I'll make a confession: I'm not a huge fan of birds. In fact, those who know me would tell you that I regularly cower when flocks of crows or seagulls decide to fly towards me.
However, I have a healthy respect for their abilities. Not only can they fly, they sit on power lines like it's no big deal. And as someone employed by an electrical utility, that strikes me as pretty impressive.
In our jobs at BC Hydro, we learn a great deal about the dangers of working near and with high-voltage electricity, and the important safety precautions that our crews need to take when working near these lines. So how is it that birds can perch and snooze on power lines without the heavy insulating gloves, special tools, or isolation orders that power line technicians require?
I needed an answer, so I went right to an expert.
UBC professor explains the science behind safety around power lines
I asked Professor William Dunford, an associate professor with the University of British Columbia's electrical and computer engineering faculty to explain how it works.
In a nutshell, he explained that if we could fly (and were as light as a bird), we'd get away with it, too.
"The advantage that birds have is that they are already far from the ground when they land on the wire, so there is no path nearby for the circuit to be completed," says Dunford.
He explained that, if you start off standing on the ground, like humans usually are, then you either have to move yourself on to an insulator before you touch the wire, or touch the wire through an insulator, such as the rubber-handled tools and gloves that power line technicians use.
One side of the electrical supply is always connected to ground. This is done so that crews know that everything is safe when the switch is off, but it also means that when you are standing on the ground, you provide a possible path from a circuit which is being used.
Although sitting casually on power lines is generally limited to birds, anyone would be safe unless a circuit is completed to provide a current path.
"I heard stories of African birds with big beaks sitting on adjacent lines and making the mistake of letting their beaks touch," Dunford says of one unexpected way that circuits can be completed. That's the same reason you won't see birds straddling two different lines.
Chelsea Watt is a writer-editor with bchydro.com.