BANGOR – Bangor Hydro-Electric customers will see their rates go up soon.

The company said Friday that transmission rate increases will result in residential customer bills increasing by about 4 percent, or roughly $3.50 a month on average for an $85 bill. Commercial and industrial customers will see their bills go up 4 percent to 5 percent, depending on their size.

The new rates go into effect on July 1.

“Transmission rates are adjusted annually every July 1. Last year, our rates actually decreased 1 percent,” Bangor Hydro spokeswoman Susan Falloon said Friday.

She said the price hikes are due mainly to increased work on transmission lines to make sure they remain reliable.

Large and medium-class customers were notified with calls or letters. Residential customers will be notified on their next bill.

“We couldn’t have let customers know any sooner because we don’t know exactly what the rate will be until it’s actually in effect,” Falloon said.

BDN staff writer Eric Russell contributed to this report.