Class 1 Div 2 debate

[cornbread]

We are having a heated debate at our site on area classification. The heart of of dispute is the need to limit the current into a class 1 div 2 area. The old timers (my self included) are saying a current limiting resistor or barrier are needed. The new folks argue if the circuit has no arcing or sparking contacts then nothing is needed? Example being a 24 Digital output 1 amp fuse that feeds a 24 VDC soleniod in a class 1 Div 2 area.


Looking for support for both side...backed up with code requirements.:jawdrop:

 

[nakulak]

It's been a while since I did this type of work, but as long as it complies with 502.120 2008 I don't see the issue ?. what is the wiring method/details of the installation ?

 

[rbalex]

Current limiting is not required in Class I, Class II or Class III, Division 1 or 2 unless you are planning to use an intrisically safe or nonincindive wiring method which permits using wiring methods for unclassified locations. For example, see 504.20.

How would you propose "current limiting" a motor branch circuit where general purpose motors are suitable for Class I, Division 2? [501.125(B)]

 

[cornbread]

Appreciate the replies. It sounds like the new guys are correct, no arcing part will meet the class 1 div 2 rating. In order to work on such a system Im assuming a hot work permit would be required?

If one were to use non incendive circuits then could one work on the system with out a hot work permit?

 

[rbalex]

Appreciate the replies. It sounds like the new guys are correct, no arcing part will meet the class 1 div 2 rating. In order to work on such a system Im assuming a hot work permit would be required?

If one were to use non incendive circuits then could one work on the system with out a hot work permit?

WOW. I haven?t been associated with the ?new guys? for well over 40 years.

Be careful to make a distinction between ?energized work? and ?hot work.? ?Energized work? permits are described in NFPA 70E and basically deal with the various electrical shock and flash-hazard boundaries, appropriate PPE and work practices. ?Hot work? is not formally defined but usually deals with the environment with respect to non-electrical conditions, such as the presence or absence of volatile atmospheres at the time of the work and may deal with non-electrical ignition sources as well, such as gas welding.

Nonincendive circuits are usually ?safe? from both perspectives, but still must be carefully analyzed, especially in ?hot work? situations. They rarely apply, to anything but control or instrumentation circuits.