ComEd GRIT Transmission Project Wins ICC Approval for Four 138 kV Lines

Construction starts this fall with grading and drainage at the Dierking substation near the Elmhurst Road corridor in the Elk Grove Village area. Underground transmission work in the other areas begins in January 2027, and ComEd expects to place GRIT in service in the second quarter of 2029.

Why ComEd Cites Large-Load Growth Near O'Hare

ComEd says GRIT is needed to serve existing customers and new load, including multiple large-load customers that have entered the Wood Dale and Elk Grove Village areas. The release does not name those customers, does not call them data centers and gives no megawatt figure for them. Voltgrid has not seen a project cost or capacity rating in the release either.

The utility says it builds only against demonstrated need, based on actual and forecast customer demand, including service requests and deposits. For developers, the practical point is timing: a line that enters service in 2029 sets when additional load in this area can be served reliably, whatever its type.

The underground design is tied to the airport. ComEd says Federal Aviation Administration height restrictions limit overhead structures near O'Hare, and that underground construction suits the developed and congested area.

ComEd's parent, Exelon, has described a large pipeline in ComEd's zone. As Voltgrid reported, Exelon put about 9 GW of high-probability large load in ComEd's northern Illinois zone, with a further 17 GW in ComEd being studied or awaiting study. GRIT's release does not link the project to those figures, so the two should not be added together.

What Is Still Unconfirmed on Cost and Capacity

The release gives no cost for GRIT, no line capacity in MVA and no breakdown of who pays. It does not say how much of the new load is data centers. Watch the ICC docket and ComEd's project page for the order text, the cost allocation and any appeals, and watch whether construction holds the January 2027 start and the second-quarter 2029 in-service date.