A solenoid coil assembly for hazardous environments comprises a solenoid coil and an enclosure entirely filled with encapsulation material. The encapsulation material leaves zero or almost zero volume in the enclosure for hazardous material to accumulate in any amount that could explode. This allows the solenoid coil assembly to be constructed without the usual industry standard flame paths. Additionally, the enclosure may be made of physically rigid and strong material such as metal or the like to better withstand harsh and corrosive conditions within hazardous environments without being explosion proof. The walls of such an enclosure need only have a moderate thickness and weight relative to enclosures that are explosion proof, as there is no meaningful risk of an explosion occurring within the enclosure. The combination of a rugged exterior and a zero-volume interior allows the solenoid coil assembly to reduce weight and cost while providing superior environmental protection.