PARIS — Work to insulate the attic of the Oxford County Courthouse hit a snag when contractors found knob and tube wiring in the roof area.

On Tuesday, commissioners decided to wait for estimates on replacing the outdated wiring before proceeding with the work, which also includes the installation of a new wood pellet boiler and converting the building’s heating system from steam to hot water.

The pellet boiler system is expected to be up and running next week, County Administrator Scott Cole said.

Richard Grondin, the County Commission’s consultant for the boiler installation project, reported to commissioners Tuesday that the wiring should be replaced before insulation is installed.

According to the International Association of Certified Home Inspectors, knob and tube wiring was an early means of wiring buildings for electricity, connecting electrical tubes with porcelain knobs. Installing insulation over knob and tube can be dangerous and is illegal in most cases. The wires are meant to run through empty wall spaces, as the porcelain knobs vent heat. Foam or blown-in insulation around one of the porcelain knobs can prevent the knobs from venting heat and can cause insulation to ignite, the association said.

Grondin said estimates for replacing the wiring range from $6,000 to $22,000. He said he’s waiting to get bids.

He said Electrical Systems of Maine, which is installing the wiring for the new burner, gave the $22,000 estimate.

“I think we should wait until we get a more accurate, second opinion,” Commissioner Stephen Merrill said. Commissioner Caldwell Jackson agreed.

The commission is also looking for a vendor for wood pellets.

The energy efficiency upgrades have been paid for by a $235,000 grant. The total cost of the project is about $275,000, Cole said.

[email protected]