New London — Tanko Lighting will begin an inventory of every street light in the city Thursday as the city begins the process of replacing all of its roughly 3,000 street lights with more efficient, brighter fixtures equipped with LEDs, or light-emitting diodes.

The inventory is expected to take two or three weeks, during which time trained auditors wearing safety vests and traveling in marked vehicles will capture data on each existing street light throughout the city, including wattage and location coordinates, the Department of Public Works said.

The conversion, which was approved by the City Council in May, carries an upfront cost of about $1.1 million, but various rebates would result in a net cost to the city of about $430,000, according to estimates provided to the city by Tanko Lighting.

In April, then-DPW Director Tim Hanser said the city’s annual electricity usage is about 3 million kilowatt-hours, which costs about $550,000. Switching to energy-efficient LEDs would induce a 73 percent decrease in the city’s electricity usage — to 820,000 kilowatts — and a 69 percent drop in its electric bill — to $170,000, Hanser said.

Once the new LED lights are operational, Hanser said, the program would pay for itself in about 13 months.

For information, contact William Camosci, DPW’s assistant director of engineering services, at wcamosci@ci.new-london.ct.us or (860) 440-6645.

— Colin A. Young