DALLAS – Thelma Taormina keeps a pistol at her Houston-area home to protect against intruders. But one of the last times she used it, she said, was to run off a persistent utility company worker who was trying to replace her old electricity meter with a new digital unit.

“This is Texas.” she declared at a recent public hearing on the new meters. “We have rights to choose what appliances we want in our home.”

A nationwide effort to upgrade local power systems with modern equipment has run into growing resistance in Texas, where suspicion of government and fear of electronic snooping have made a humble household device the center of a politically charged showdown over personal liberty.

Some angry residents are building steel cages around their electric meters, threatening installers who show up with new ones and brandishing Texas flags at boisterous hearings about the utility conversion. At a recent hearing at the state Capitol in Austin, protesters insisted everyone present recite the Pledge of Allegiance before the meeting could begin.

“It’s Gestapo. You can’t do this,” said Shar Wall of Houston, who attended the Public Utility Commission meeting wearing a large red “Texas Conservative” pin. “I’m a redneck Texas girl and I won’t put up with it.”

Utilities began replacing old-style electricity meters across the country about seven years ago as part of an effort to better manage demand on an increasingly strained power grid. New “smart meters” transmit and receive data remotely as electricity is used. Utility officials say they can use the real-time information to help prevent grid overloads during extreme temperatures. The devices would also promote conservation, such as cycling air conditioners on and off during peak demand periods.

In 2009, President Barack Obama devoted $3.5 billion in federal stimulus funds to help utility companies make the upgrade.

The conversion has triggered opposition in a number of states. Some residents have questioned the health impact of the radio waves the devices emit or the possibility that hackers could get confidential data from the transmissions.

Officials downplay the hazards, but several states, including California, Vermont, Maine and Nevada, have allowed residents to opt out of the new system. In most cases, residents would have to pay extra to have a utility employee come to their house to read their old meter.

Texas utilities have installed nearly 6 million smart meters, or 87 percent of their goal, since the state passed authorizing legislation in 2005. But as the project moves toward completion by 2016, the opposition is getting louder. It also carries the distinct flavor of an ultraconservative state that relishes its history as an independent republic before joining the United States.

State utility commission hearings on the meters have featured as many references to the Founding Fathers, the Revolutionary War and the Constitution as to the technical demands on the power system.

At a recent session, a staff presentation included a slide saying the new meters “are not meant to spy on you.” Waiting to testify, activist David Akin replied, “Yes, they are!”

Some say the meters would allow the police or other government agencies to tell when a person was awake and what they were doing, in violation of the Fourth Amendment.

“I’m not going to let somebody else control what I do in my house,” said Ginger Russell, who recently replaced her “No Smart Meters” sign with a steel cage around her home’s analog meter in the East Texas town of Magnolia.

Those emphasizing privacy concerns cite a report issued by the U.S. Department of Energy in January that said many companies had not done enough to protect the smart meters from hackers. Some studies have also added to the health concerns. A branch of the World Health Organization last year called radio-frequency radiation from cellphones, utility meters and other devices a “possible carcinogen.”

However, the Federal Communications Commission has rated the smart meters as safe.

The Texas utility commission will consider this fall whether to allow Texas residents to opt out.