This is a type of installation that always bothers me. If the area has to be classified, (it appears that may not be the case here), where do I find a truck rated for Class I, Division 2 areas? If the truck itself, a much more likely ignition source than the electrical system, doesn't have to be rated for the area, I see no real reason why the electrical system would have to be.
I honestly hear you Don.
The philosophy is basically stated in 500.1: ?Articles 500 through 504 cover
the requirements for electrical and electronic equipment and wiring for all voltages in Class I, Divisions 1 and 2; Class II, Divisions 1 and 2; and Class III, Divisions 1 and 2 locations where fire or explosion hazards may exist due to flammable gases, flammable liquid?produced vapors, combustible liquid?produced vapors, combustible dusts, or ignitible fibers/flyings.?
This philosophy is emphasized in both NFPA 497 and API RP 500:
1.1.2 This recommended practice provides information on specific flammable gases and vapors, flammable liquids, and combustible liquids, whose relevant combustion properties have been sufficiently identified to allow their classification into the groups established by NFPA 70, National Electrical Code? (NEC?), for proper selection of electrical equipment in hazardous (classified) locations. The tables of selected combustible materials contained in this document are not intended to be all-inclusive. [NFPA 497]
1.1.1 The purpose of this recommended practice is to provide guidelines for classifying locations Class I, Division l and Class I, Division 2 at petroleum facilities for the selection and installation of electrical equipment. Basic definitions given in the 1996 edition of NFPA 70, the National Electrical Code (NEC), have been followed in developing this recommended practice. This publication is only a guide and requires the application of sound engineering judgment.[API-RP 500]
[All Underlines mine]
While those of us who (properly
) do the classification, may often consider other
constant sources of ignition as a basis for reducing or even eliminating classification, we still classify to properly select and design the
electrical installation.
I had a project that attempted to use my electrical area classification to determine structural fireproofing. When it became obvious the cost would go through the roof (relatively), the ?logical? answer was to have me change the electrical area classification ? which I refused to do.
One of the primary differences between US domestic and ?classic? IEC classification, is the term
electrical is dropped. That is, there is only ?area classification? and it is used for all sorts of plant layout. Until a common system of classification is adopted by all disciplines, those of us that have influenced the general field of electrical area classification want it restricted to electrical installations, especially in light of NEC Section 90.2 (B)(1).
