The Federal Motor Carrier Safety Administration clarified its rules for tank carriers providing service in a home heating emergency.

Right now, these carriers can get a 30-day exemption from some federal safety rules, including hours of service, when a governor has declared an emergency shortage of home heating oil.

The agency has been able to extend the exemption but now says that if the emergency persists longer than 30 days the governor can extend the exemption for an additional two months.

The change is scheduled for publication in Wednesday’s Federal Register.