I believe the Federal Motor Carrier Laws state you can only drive 10 hours straight without a break and/or only drive for X amount of time within a 72 hour period. I apologize that I cannot remember the hours of service within the 72 hour period off the top of my head.
I'm not sure if Ohio has any exemptions for emergency workers such as firemen and Utility workers.
Where it may get tricky with interpretation is that it is really the driving time that is governed. If you are working on a pole, you are not driving a CDL vehicle and that time should not be counted.
They are really using a drivers actual driving time when they write these laws. It was never really designed for us Utility workers. We got caught up in it as a technicality because we drive vehicles that require a CDL license and therefore must abide by the laws that govern other CDL drivers.