Variable Freq. Drives on Hazardous Location motors.

[voltairzap]

What is the rule on installing a VFD on a classified motor. Class 1 div 2. The VFD would be outside the classified area.
It seems that somewhere I have seen a limitation on the VFD/motor combination unless both were listed as suitable for this use.
I don't see the rule in the NEC.

 

[rbalex]

As a general rule, except for some very specific applications, motors are not listed for Class I, Division 2. While UL has a standard for motors, the NEMA Motor Group pretty much ignores it for GP and Division 2 motors.

NEMA MG-1 states:

12.9 Operation in Hazardous (Classified) Locations
WARNING—Motors operated from adjustable frequency or adjustable voltage power supplies or
both, should not be used in any Division 1 hazardous (classified) locations unless the motor is
identified on the nameplate as acceptable for such operation when used in Division 1 hazardous
(classified) locations.
For motors to be used in any Division 2 hazardous (classified) locations, the motor manufacturer should
be consulted.
Failure to comply with this warning could result in an unsafe installation that could cause damage to
property or serious injury or death to personnel, or both. [MG 1-30.2.2.10]