ISA 60079-26

This standard specifies the particular requirementsfor construction, test and marking for electrical apparatus ofGroup II intended for use in Class I, Zone 0 as defined inthe National Electrical Code, ANSI/NFPA 70.

This electrical apparatus, within the operational parametersspecified by the manufacturer, ensures a very high level ofprotection that includes rare faults related to the apparatus ortwo faults occurring independently of each other.

NOTE 1 A malfunction may result from a failure of the componentparts of the electrical apparatus or from anticipated externallyapplied influences. Two independent malfunctions which may occurmore frequently and which, separately, would not create an ignitionhazard but which, in combination, could create a potential ignitionhazard, should be regarded as occurring together to form a rarefault.

This electrical apparatus is intended for use in Class I,Zone 0 hazardous areas, in which explosive gas atmospheres causedby mixtures of air and gases, vapours or mists under normalatmospheric conditions are present continuously, for long periodsor frequently.

This standard also applies to apparatus mounted across theboundary between Class I, Zone 0 and Class I, Zone1.

EXAMPLE: In the wall of a storage vessel.

This standard also applies to apparatus installed outsideClass I, Zone 0, but electrically connected to apparatusinside Class I, Zone 0 (associated apparatus).

This standard supplements the general requirements inANSI/ISA-60079-0

NOTE 2 In designing apparatus for operation in explosive gasatmospheres under conditions other than the atmospheric conditionsgiven in IEC 60079-0, this standard may be used as a guide.However, additional testing is recommended related specifically tothe intended conditions of use. This is particularly important whenthe types of protection ‘Flameproof enclosure'(ANSI/ISA-60079-1) and ‘Intrinsic safety’ (ANSI/ISA-60079-11) are applied.

NOTE 3 The classification of hazardous areas in zones is definedin the National Electrical Code.

NOTE 4 There may be other non-electrical sources of ignition(for example ultrasonic, optical or ionizing radiation) that arenot addressed by this standard; these should also be taken intoconsideration (see, for example, EN 1127-1).

Edition:

08

Published:

01/01/2008

ANSI:

ANSI Approved

Number of Pages:

28

File Size:

1 file , 98 KB