A divided Pennsylvania Public Utility Commission, indicating that the state's low-income customers may be paying too much of their household incomes on utility bills, voted Thursday to launch a one-year study of "home energy burdens."

In a rare 3-2 party-line split, commission members voted to explore the sensitive issue of how much low-income customers should be required to pay for monthly energy costs. State policy established in 1992 sets the limit at 17 percent of a household's income.

But PUC Vice Chairman Andrew G. Place, joined by Commissioner David W. Sweet, said the steady volume of complaints from low-income customers who are unable to keep current on their discounted payment plans suggested that the state's limit for its customer-assistance programs "may be too high."

Place said the average Pennsylvania household not enrolled in a low-income program pays about 5 percent of household income on utility bills. He suggested a national average of 6 percent to 11 percent of household income "may be more appropriate."

Place and Sweet were joined by Chair Gladys M. Brown in directing the PUC's Bureau of Consumer Services to report back in a year on appropriate levels of home energy costs.

The two Republican commissioners, John F. Coleman Jr. and Robert F. Powelson, dissented, expressing concern that looking only at the energy burden for low-income customers ignored the broader implications of increasing subsidies to low-income households.

The costs of those programs are typically paid by other residential customers. Statewide, the cost of low-income subsidies increased from $63 million to $253 million between 2000 and 2015, Coleman said.

He suggested that a more "comprehensive review" of the costs of customer-assistance programs was in order, "rather than the more narrowly focused study of energy burden."

Place and Sweet had negotiated with their colleagues behind closed doors for a month in a failed effort to seek unanimity for their statement. "I have to say I'm disappointed, but given the tenor of the times, not surprised," Sweet said.

He said a broader inquiry into assistance programs could be built on the more narrowly focused study of energy burdens on low-income customers, and noted that he planned to introduce a measure in April that would seek to launch a comprehensive review.

"Hopefully, we'll have unanimity," he said.