gas or vapor, specific mixtures of gases or vapors, or any specific combination of gases or vapors.
FPN: One common example is equipment marked for
"IIB. + H2."
(C) Marking. Equipment shall be marked in accordance with 505.9(C)(1) or (C)(2).
(1) Division Equipment. Equipment identified for Class
I, Division 1 or Class I, Division 2 shall, in addition to
being marked in accordance with 500.8(C), be permitted to be marked with all of the following:
(1) Class I, Zone 1 or Class I, Zone 2 (as applicable)
(2) Applicable gas classification group(s) in accordance with Table 505.9(C)(1)(2)
(3) Temperature classification in accordance with
505.9(D)(1)
Table 505.9(C)(1)(2) Gas Classification Groups
Gas Group Comment
IIC See 505.6(A) IIB See 505.6(B) IIA See 505.6(C)
(2) Zone Equipment. Equipment meeting one or more of the protection techniques described in 505.8 shall be marked with all of the following in the order shown:
(1) Class
(2) Zone
(3) Symbol "AEx"
(4) Protection technique(s) in accordanc with Table
505.9(C)(2)(4)
(5) Applicable gas lassification group(s) in accordance
with Table 505.9(C)(1)(2)
(6) Temperature classification in accordance with
505.9(D)(1)
Exception No. 1: Associated apparatus NOT suitable for installation in a hazardous (classified) location shall be required to be marked only with (3), (4), and (5), but BOTH the symbol AEx (3) and the symbol for the type of protection (4) shall be enclosed within the same square brackets, for example, [AEx ia] IIC.
Exception No. 2: Simple apparatus as defined in 504.2 shall not be required to have a marked operating temperature or temperature class.
Electrical equipment of types of protection "e," "m," "ma," "mb," "px," "py," "pz," or "q" shall be marked Group II. Electrical equipment of types of protection "d," "ia," "ib," "[ia]," or "[ib]" shall be marked Group IIA, IIB, or IIC, or for a specific gas or vapor. Electrical equipment of types of protection "n" shall be marked Group II unless it contains enclosed-break devices, nonincendive components, or energy-limited equipment or circuits, in which case it shall be marked Group IIA, IIB, or IIC, or a specific gas or vapor. Electrical equipment of other types of protection shall be marked Group II unless the type of protection utilized by the equipment requires that it be marked Group IIA, IIB, or IIC, or a specific gas or vapor.
FPN No. 1: An example of the required marking for intrinsically safe apparatus for installation in Class I, Zone 0 is "Class I,
Zone 0, AEx ia EC T6." An explanation of the marking that is required is shown in FPN Figure 505.9(C)(2).
FPN No. 2: An example of the required marking for intrin- sically safe associated apparatus mounted in a flameproof enclosure for installation in Class I, Zone 1 is "Class I, Zone 1
AEx d[ia] IIC T4."
FPN No. 3: An example of the required marking for intrin- sically safe associated apparatus NOT for installation in a hazardous (classified) location is "[AEx ia] IIC."