CHICAGO (CBS) — Electric bills are going up for ComEd customers next month. WBBM’s Nancy Harty reports that follows a move by state regulators to approve a rate increase.

The increase amounts to about $5.50 per customer and is on delivery charges so it doesn’t matter if you have another electric supplier.

Executive director of the Citizens Utility Board David Kolata says the increase wasn’t a surprise given a new law that sets a formula for rate hikes.

“It is never a good day when you have a big rate increase like this. The commission’s hands were tied a bit by the law that passed last year,” said Kolata.

He pledges that CUB would hold ComEd accountable.

“The key thing is to make sure that the smart grid investments that these rate increases are paying for are done appropriately,” said Kolata.

In a statement, ComEd says the $340 million increase follows a drop in energy prices and will allow the utility to invest in the smart grid which should increase reliability.