Plans by the Federal Communications Commission to commercialize radio spectrum currently reserved for critical utility communications is raising concern at high levels.

The Federal Energy Regulatory Commission is asking the FCC to proceed with caution on its proposal to open the 6-gigahertz band, already heavily used by utilities, to unlicensed users.

“As you consider how the FCC will proceed on its 6 GHz spectrum band proposal, we ask that you consider the implications for electric reliability and closely review the rulemaking comments that discuss the potential impacts of the proposal on electric reliability,” FERC wrote in a letter to FCC Chairman Ajit Pai.

“Many electric utilities use the 6 GHz spectrum band to support their real-time operations, including supervisory control and data acquisition that is used to monitor and control generating units, transmission lines, and substation equipment as well as system protection.”

To keep unlicensed users from interfering with utilities’ communications, the proposal relies on a system—Automated Frequency Coordination—that is not fully tested, FERC noted.

If the FCC finalizes this rule, “we strongly urge you to consider requests from electric utilities and state regulators for additional testing of the AFC system prior to implementation,” FERC said.

“Reliable and safe delivery of utility services depends on strong communications, which should not be placed at risk,” said Jay Morrison, NRECA vice president of regulatory issues. “We thank FERC commissioners for sharing their concerns with Chairman Pai about the significant risk of FCC’s proposal to open the 6 GHz band.”

The commission’s Dec. 18 letter follows a technical workshop held at FERC and concerns raised by the Department of Energy, the National Association of Regulatory Utility Commissioners, NRECA and other utility organizations about the FCC proposal.

NRECA, the American Public Power Association, the American Water Works Association, the Edison Electric Institute and the Utilities Technology Council underscored the need for uninterrupted communications and urged the FCC not to rush into opening this channel.