AGNEW — “Notoriously unreliable” insulators at the Clallam County Public Utility District’s Agnew substation were blamed for a six-hour power outage to about 2,500 customers Monday morning.

Clallam PUD’s board of commissioners received an update later Monday on that power failure as well as a Friday mornings outage in the Carlsborg area.

Chief Engineer Dave Proebstel said the design of the insulators, which protect transmission lines where they are connected to the substation, allows moisture to get inside.

The freezing and thawing of the past few days probably cracked some of the insulators, causing them to fall off and grounding the substation about 8:30 a.m., he said.

The substation was shut off for repairs, knocking out power to customers in the Agnew area, Proebstel said.

The work included replacing 41 insulators, and power began getting restored in sections by about 2:30 p.m., he said.

The same type of insulators will be replaced this summer at the Beaver Camp substation, Proebstel said.

Friday’s power outage in the Carlsborg area was the result of cold weather coinciding with a project to hook up power to a new car wash next to Sears, Proebstel said.