Is it acceptable to install a NEMA 4 enclosure and push-buttons, indicators in a Class II, Div. 2, Grp. F&G hazardous area? There will be a VFD inside the control panel along with other non-rated components. The control panel will be installed in the USA.
I am getting conflicting advice on this.
On one hand, my local panel builder is telling me that I need to purge the panel with an enclosure purge system.
On the other hand, I have a NFPA book entitled "Electrical Installations in Hazardous Locations, 3rd edition, written by Peter J. Schram (NFPA's Chief Electrical Engineer) and Mark W. Eraley (Assistant Chief Electrical Engineer, staff liason to the National Electrical Code) (ISBN0-87765-356-9) that reads...
"4-3.2.2 Dusttight Equipment
For most equipment in Class II, Division 2 locations, the National Electrical Code indicates that dusttight equipment can be used.
Dusttight equipment is defined in the National Electrical Code as "so constructed that dust will not enter the enclosing case under specified test conditions." A fine priont note is added referencing ANSI/NEMA 250, paragraph 250.5.05. This reference indicates that either of two different test methods can be used: A dust-blast method or an atomized water method.
NEMA and UL designations for dusttight equipment are Types 3, 3S, 4, 4X, 6, 6P, 12, 12K and 13. NEMA Type 9 enclosures (dust ignitionproof) are also accepted."
Reading the above, it would appear that a NEMA4 enclsoure and operators, lights, etc. would be acceptable for a Class II, Division 2, Group F&G hazardous area.
What is accepted in the USA?