IL SB1494

Defines "underground" or "undergrounding" as routing and constructing electric transmission lines and associated components below ground consistent with sound engineering practices.

Requires public utilities to underground any 138 kilowatt or greater electric transmission lines constructed after the effective date if located within 26,000 feet of a municipality-owned airport in a city with population between 70,000-80,000 in/contiguous to a county with over 1,000,000 residents, or if spanning 4 or more contiguous municipalities with population density of 1,000 per square mile or more.

Allows the Illinois Commerce Commission to permit public utilities to recover all reasonable and prudent undergrounding costs from all retail customers in their service territory, rather than only from customers in the specific municipalities where the lines are undergrounded.

Requires utilities to record and defer undergrounding costs as a regulatory asset included in the utility's rate base and amortized over a period equal to the expected life of the transmission line.

Takes effect immediately upon becoming law.