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DTE Electric 4.8kV Technical Conference

The DTE Electric distribution system has overhead and underground lines at varied voltages.  The two dominant voltages in its system are 4.8kV and 13.2kV. 

Higher voltage distribution systems have greater capacity, allowing them to deliver more electricity to the areas they serve. As Michigan households and businesses increasingly electrify by purchasing electric vehicles and other electric powered technologies, the capacity limitation from lower voltage distribution systems may present issues.  DTE Electric recognizes that all 4.8kV systems must be converted to 13.2kV.  However, the process takes time.

Currently, DTE Electric addresses the 4.8kV system challenges in two main ways: conversion and hardening.  In conversion, the company converts the 4.8kV system to the higher 13.2kV system.  In hardening, the company makes investments to the existing 4.8kV system to improve reliability and safety while it awaits future conversion. 

“Arc wire” refers to the remaining wires of the former Detroit Public Lighting Department system.  These arc wires, though no longer in service or energized, can pose safety hazards when they fall, becoming a “downed wire,” and contact energized overhead electric distribution lines.   

In the 2022 DTE Electric rate case (Case No. U-20836), the Commission ordered the company to conduct one or more technical conferences by the end of the first quarter of 2023 on the 4.8kV system to fully explore the benefits and costs of hardening the 4.8kV distribution system in DTE Electric’s territory versus other potential alternatives such as conversion and tree trimming.  The Commission also requested a status update regarding the company’s arc wire removal efforts.


The Commission identified the following objectives for the 4.8kV Technical Conference:

  • Complete a full analysis that demonstrates the specific costs of hardening, conversion, DERs, tree trimming, and/or other alternatives compared with the benefits, such as improving safety and reducing SAIDI and SAIFI;
  • Conduct an analysis of the capabilities/constraints of the 4.8kV system and how it affects the use of DERs and EVs compared to conversion to a 13.2kV system;
  • Complete a full analysis and comparison of alternatives to hardening including, but not limited to, the use of DERs such as solar, storage, energy efficiency, and microgrids;
  • Complete a full analysis of optimal reliability-focused distribution technologies and plan a course of action for arriving at an equitable future for environmental justice and other disadvantaged communities; and
  • Calculate the miles of arc wire removed to date, the estimated miles of arc wire remaining, the level of confidence that all arc wire is captured in the company’s inventory, and the cost of removal with the 4.8 kV hardening program and the cost without the program.

Actions to Date

On March 22, 2023, the first technical conference on the DTE Electric 4.8kV system occurred.

On March 13, 2023, the Request for Proposals (RFP) for the Utility Distribution System Audit for Consumers Energy and DTE Electric was issued.  Responses to the RFP are due by April 25, 2023.

On November 18, 2022, the Commission order in Case No. U-20836 established the need for one or more technical conferences in the first quarter of 2023 with the objectives listed above.

On October 5, 2022, the Commission ordered a third party audit of the electric distribution systems of DTE Electric and Consumers Energy in Case No. U-21305.  This audit will compare the relative benefits and costs of different options to improve reliability, including grid hardening, tree trimming, other O&M, and conversion to higher voltage levels where applicable.  The audit findings should shed light on the 4.8kV system and alternatives to improve reliability.

Next Steps

DTE Electric will review related comments and questions from the March 22, 2023, technical conference and follow up with additional information.  This information will be posted to this website after it is received by MPSC staff.

Stakeholder Sessions

March 22, 2023: Technical DTE Technical Conference (Teleconference Only)

Agenda | Presentations | Recording | Follow-up Responses
Due to technical difficulties with the recording, brief moments of the recording may be missing.  We apologize for the inconvenience.

Staff Lead

Joy Wang

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