SAN FRANCISCO (AP) ” Two environmental groups and the state of California are challenging the federal government’s energy-efficiency standards for electrical equipment.

The petitions urge the U.S. Department of Energy to adopt stronger standards for the country’s 40 million electricity distribution transformers that control energy use in homes and businesses. The transformers are mounted in gray boxes on utility poles nationwide.

The petitions were filed Monday by the Sierra Club, Natural Resources Defense Council and California Attorney General Jerry Brown.

The plaintiffs say the standards adopted by the Energy Department in October will lead to excessive electricity use and greater emissions of greenhouse gases blamed for global warming.

Copyright 2007 The Associated Press.