The Pennsylvania Public Utility Commission on Thursday cracked open the door for opponents of the state's compulsory smart-meter deployment policy, allowing a hearing on a customer's complaint that the installation of a wireless meter outside her bedroom caused her to get sick.

In a 4-1 vote, the PUC rejected Peco Energy Co.'s petition to prevent an administrative law judge from hearing the health complaints of Susan Kreider, a registered nurse who said she suffered "deleterious health effects" after Peco installed the new meter on her Germantown home in 2013.

The commission has previously declined to hear scores of complaints from smart-meter opponents, who object to the devices on privacy, safety, or health grounds. Utilities say they are required to install the meters to comply with Act 129, a 2008 energy-conservation law that ordered all Pennsylvania utilities to deploy the devices.

Kreider's complaint was different, the PUC said, because she said she could produce medical documentation showing that the electromagnetic radiation from the meter caused her to get sick. The meter violates the state's public utility code requiring utilities to provide "safe and reasonable" service, she has maintained.

"To ignore claims relating to the safety of smart meters would be an abdication of our duties and responsibilities under . . . the code," the PUC said in its order Thursday.

Kreider has said her illness was diagnosed as a vaccine injury, a variant of Guillain-Barre syndrome, that makes her susceptible to the smart meter's signal. She said she suffered from elevated blood pressure and a loss of sleep.

Her health improved, she has said, after she paid an electrician in 2014 to replace Peco's smart meter with an old-style analog meter she bought on the Internet for $85. She mailed the uninstalled device back to Craig Adams, Peco's chief executive.

Kreider, 58, declined to comment Thursday, saying the matter is still under litigation.

Cathy Engel Menendez, Peco's spokeswoman, declined to comment on Kreider's case, but said there was no scientific evidence that the technology causes adverse health effects.

"We look forward to continuing to work with all interested parties and coming to a resolution in the near future," she wrote in an email.

Commissioner Pamela A. Witmer, the PUC's lone dissenting vote, said Kreider's case should be dismissed as legally insufficient.

"I agree with Peco that nothing alleged by complainant here is new, novel or necessitating an additional hearing," Witmer said.

Smart meters allow utilities to establish two-way communication with each customer, giving utilities greater control over their networks and allowing customers to respond to pricing signals from the utilities.

Peco has spent $733 million to install 1.7 million meters, including a wireless communications network linking the devices.

In its request to the PUC to reconsider a September decision allowing Kreider's hearing, Peco said it feared the PUC was departing from established policy just as the utility completed its five-year smart-meter project.

"Now is not the time to change the rules of the road related to universal installation of this technology," Peco argued.

The PUC said its Thursday order was narrow, based on Kreider's specific allegations, and "not intended to create the broad-reaching precedent" that Peco fears.