I have a junction box that will be housing terminal blocks being used as a termination point for field devices. The box is located in a Class II div 1 (Zone 21) hazardous area.
The terminal blocks are WDU 2.5, with a rating of Ex eb II C Gb
The rules read:
18-200 Equipment, Zone 21 locations (see Appendix B)
Electrical equipment installed in a Zone 21 location shall be in accordance with Table 18.
18-202 Wiring methods, Zone 21 (2) : Boxes, fittings, and joints shall be threaded for connection to conduit or cable glands, and boxes
and fittings shall be suitable for use in Zone 21 locations.
The way I read this is that the box must be "suitable for use" and not marked for use in Zone 21 so it could be any dust-tight general purpose box, however the equipment (Terminal blocks) are not rated for the hazardous area so must be encapsulated by a enclosure rated ta or tb as per table 18
What makes me second guess it is that 18-150 Equipment, Zone 2 locations (2c) had a specific permissive for enclosures that reads:
Notwithstanding Subrule 1) and Rule 18-052, the following shall be permitted:
equipment that is installed in a Type 4 or 4X enclosure, or an IP65 or higher enclosure, and is
i) non-sparking in normal operation;
ii) not used for heating purposes; and
iii) not otherwise provided for in Subrule 2);
Terminal blocks meet the CEC definition for electrical equipment.
Can anyone advise to similar installations.
The terminal blocks are WDU 2.5, with a rating of Ex eb II C Gb
The rules read:
18-200 Equipment, Zone 21 locations (see Appendix B)
Electrical equipment installed in a Zone 21 location shall be in accordance with Table 18.
18-202 Wiring methods, Zone 21 (2) : Boxes, fittings, and joints shall be threaded for connection to conduit or cable glands, and boxes
and fittings shall be suitable for use in Zone 21 locations.
The way I read this is that the box must be "suitable for use" and not marked for use in Zone 21 so it could be any dust-tight general purpose box, however the equipment (Terminal blocks) are not rated for the hazardous area so must be encapsulated by a enclosure rated ta or tb as per table 18
What makes me second guess it is that 18-150 Equipment, Zone 2 locations (2c) had a specific permissive for enclosures that reads:
Notwithstanding Subrule 1) and Rule 18-052, the following shall be permitted:
equipment that is installed in a Type 4 or 4X enclosure, or an IP65 or higher enclosure, and is
i) non-sparking in normal operation;
ii) not used for heating purposes; and
iii) not otherwise provided for in Subrule 2);
Terminal blocks meet the CEC definition for electrical equipment.
Can anyone advise to similar installations.