Hawaiian Electric Co. will begin a three-week series of overnight outages tonight that will affect customers in the Iwilei, Kakaako and Ala Moana areas.

The outages are part of a $1.5 million infrastructure upgrade of underground cabling that is expected to improve service reliability for customers in the affected areas.

The outages, which will affect approximately 400 businesses and 2,500 residential customers, will occur Mondays through Fridays, 10 p.m. to 6 a.m., concluding on or before Aug. 2, HECO said.

Work will be done on separate circuits affecting different areas each night, so while no customer will be without power every night, some will be affected by multiple outages, according to HECO.

The scheduled repairs come after a string of more than a dozen outages involving six circuits that are to be upgraded.

HECO previously reported that its engineers had traced the problem to flaws in coupling devices (known as splices) that connect high-voltage cables to the circuits that supply power to customers.

HECO said the faulty splices can affect reliable service and pose a safety risk to crews that work in manholes.

The repairs will begin in Iwilei and proceed to Kakaako and Ala Moana. To safely make repairs and minimize disruption, the crews will need to shut down equipment in about 70 manholes, which will result in the outages.

Motorists are being asked to exercise caution while driving in areas in which HECO crews are working. Up-to-date lane closure and parking restriction information will be shared via HECO’s Twitter account at @HwnElectric.

For more information, call 548-7311 or visit hawaiian electric.com/Underground Upgrades.