Type EE vs. Type EX
EE rated equipment is authorized for use in Division 2 designated hazardous areas. Whereas, EX equipment is suitable for operation in both Division 1 and Division 2. Under normal conditions in Division 1 areas, hazardous levels of flammable gases, vapors or dusts can exist all the time. Furthermore, In D2 areas, hazardous levels are not likely to exist because flammable liquids, gases & dusts are in closed containers.
EE equipment is used in Division 2 areas where flammable or explosive materials are stored in sealed containers or drum. If a sealed container is pierced by a fork or dropped, the resulting rupture makes the D2 area immediately volatile. This creates an instant Division 1 environment. Under these circumstances, the use of EE equipment is no longer safe and could result in fire or explosion.
Type Designation EE
Defined as: “An electrical powered unit that, in addition to meeting all the requirements for Type E and ES units, has its electrical motors and all other electrical equipment completely enclosed.” NFPA 505(2002)188.8.131.52
In Type EE construction, motors and switches should be enclosed to prevent sparks from escaping. Also, all flexible leads should be in non-metallic looming or tubing. Those working in some Division 2 designated hazard areas are authorized to use EE equipment.
Type EE equipment rating does not protect against explosive mixtures of gases or dusts in the atmosphere. Continually, the EE rating does not protect against:
- static discharges in atmosphere,
- auto ignition temperatures generated during normal forklift operation
- electrical system failures.
No one should use this equipment in any Division 1 designated area.
Type Designation EX
Electrically powered units where electrical fittings and equipment are designed, constructed and assembled to EX designation can be used in atmospheres containing specifically named flammable vapors, dusts, and under certain conditions. NFPA505(2002)184.108.40.206
EX equipment must meet the fire and shock hazard requirements of UL583. In addition, EX equipment must have Explosion Proof enclosures (for Class 1, Division 1). As well as dust-ignition proof enclosures (for Class II, Division 1), in accordance with UL1203. EX equipment (for Classes I and II, Division 2 and Class III) must meet UL1604 specs. This means the circuits and components are incapable of causing ignition of the flammable gases or vapors in the environment. In like manner, Articles 500-504 of the National Electric Code define and set forth the rigid requirements for EX equipment labeled for use in Class I, Divisions 1, 2, Groups C,D and Class II, Divisions 1, 2, Group G.
The Wrong Idea of EE Rating
The machines represent an impression people can use them in dangerous locations. These EE machines have minimal spark protection. Therefore, they do not comply with the strict electrical requirements of NFPA 70 (NEC) for hazardous areas.