Electric bills are going up by about $5 a month.

Hawaiian Electric Co. said yesterday that the state Public Utilities Commission granted its request for a 3.3 percent interim rate hike to pay for major capital improvements over the past 10 years.

The increase, which went into effect yesterday, is HECO's first in its base rate since 1995, when it raised rates by 1.3 percent.

On top of the base rate, electric bills have been rising because of higher fuel costs. In the past year, fuel costs have added about 16 percent to the typical bill.

"We know any rate increase is tough on our consumers," said Robbie Alm, HECO's senior vice president for public affairs. "As Hawai'i's economy has struggled, we have worked hard over the past decade to avoid asking for an increase. At the same time, we have invested close to a three-quarters of a billion dollars in major service improvements to our transmission system, upgraded underground cables and other reliability projects."

Under the PUC's order, the average residential household using 600 kilowatt-hours a month will see its bill rise from $112.69 to $117.74, HECO said.

HECO lowered its original request for a 5.4 percent rate increase earlier this month after objections were raised by the state consumer advocate and the Department of Defense, which is a major electricity user.

HECO has asked for a separate 1.9 percent rate increase that is still before the PUC. The latter rate increase, to pay for the expansion of HECO's energy-efficiency and energy- conservation programs, probably won't be decided until next year.

The rate increase announced yesterday will generate about $41 million in additional revenues to pay for major capital investments that HECO made in the last decade, including: