Engine Block Heaters

Q: A consultant told me that emergency generator rooms are required to be maintained at least 40 degrees F. Do I need to maintain that temperature if I have block heaters on the engine?

A: Yes, you do need to maintain at least 40° F ambient room temperature especially when you have engine water jacket heaters that maintains the temperature of the engine water at a minimum of 90° F. Section 5-6.7 of NFPA 110 (1999 edition) clearly states that the emergency power supply (EPS) room temperature must be at least 70° F unless you have water jacket heaters that maintains the water temperature of the engine at 90°F; then you are allowed to lower the EPS room temperature to 40°F. So, this would mean the room needs to be maintained at a minimum of 40°F.