Hydro One says an outage that knocked out power to 250,000 Toronto residents Tuesday night was caused by two lines touching.
Mike Penstone, a Hydro One vice-president, says it happened when a transmission line came into contact with a distribution line that was built under it.
Penstone says increased demand causes wires to build up heat, and they sag.
He says that caused the two wires to touch, creating a flash that knocked out the power.
Penstone says to ensure it doesn’t happen again, they will create more space between the two lines, giving them an extra buffer.
Tuesday night’s outage caused some subway service to be suspended because of signal problems until about 11 p.m.