NORTH AMERICAN INSTALLATION & WIRING CODE RULES

Historically, the NEC / CEC wiring, installation and protection methods are based around a conduit system where seals are required at the point of entry to equipment required to be explosion proof. Although still widely used, conduit systems are being replaced with flexible armored and non-armored cables, with suitable cable glands providing the required sealing protection.

When conduits are to be terminated into enclosures with Non-Threaded entries, a 'hub' is required to provide grounding and ingress protection. This practice is necessary for conduit entries but can greatly reduce the available terminating space on enclosures and can add significant cost to the installation. By using cable and cable glands, simple accessories such as, entry thread seals, serrated washers and locknuts, can be used to produce the same grounding and ingress protection levels provided by 'hubs', thus reducing installation time, space utilisation and cost.

The CMP cable gland product series has been tested in this method to UL514B, Nema 4, and IEC 60529 to IP66, IP67 & IP68. The illustration below shows an example of a CMP cable gland installed in a clearance hole using standard accessories which delivers a highly cost effective solution in the sealing of cable entries when the enclosure is not required to be explosion-proof.

Cable Wiring Methods

The use of flexible cables in North America has provided industry with a wide choice of wiring methods. However, there are differences between the NEC and CEC for cables suitable for use in Hazardous areas and extreme care should be taken during the selection process. i.e. A cable type may be acceptable for use in Class I Division 1 in Canada, but not in the USA.

It is essential that the wiring method chosen is permitted for use within the area classification for the relevant code being utilized.

Cable Wiring Methods - Class I, Division 1 & Zone 1

Complete lists of suitable cable types for use in hazardous areas can be found by consulting the current NEC and CEC handbooks. Additional information for common cable types approved for offshore installations can be found by consulting section 43 of IEEE Standard 45 and API RPI 14F & 14FZ.

As a general rule, cables for use in Class I Division 1 and Zone 1 areas must be mechanically protected by armor. e.g. MC-HL and Wire Braid Armor (offshore) cables. In Canada, Interlocked armor can be also be used. e.g. Teck 90

Cable Seals, Class I Division 1 & Zone 1

Where cables enter Class I Division 1 or Zone 1 AEx d enclosures, the cable must be sealed at the point of entry with an approved device to UL 2225 or CSA 22.2, Class I Division 1 or Zone 1 AEx d, where applicable. The sealing fitting or 'Barrier' gland must prevent the passage of gas or vapours through the gland by providing a compound barrier seal around each individual insulated conductor. e.g. CMP TMCX or PX2KX cable connectors

NEC 2005
Article 501.15 (E) (1) Terminations. Cables entering enclosures that are required to be explosion proof shall be sealed at the point of entrance. The seal shall comply with 501.15(B)(1)

NEC 2005
Article 501.16 (C) (2) Cable Seals. (a) Explosion proof and Flameproof Enclosures. Cables entering enclosures required to be flameproof or explosion proof shall be sealed at the point of entrance. The seal shall comply with 505.16(D).

Note; A sealing device certified for Class I Division 1 may be used in Class I Zone 1 AEx d equipment. However, a sealing device certified ONLY for Class I Zone 1 AEx d CANNOT be used in Class I Division 1 equipment. See 501-5(d) of the NEC for further information

Cable Wiring Methods - Class I, Division 2 & Zone 2

Complete lists of suitable cable types for use in hazardous areas can be found by consulting the current NEC and CEC handbooks. Additional information for common cable types approved for offshore installations can be found by consulting section 43 of IEEE Standard 45 and API RPI 14F & 14FZ.

As a general rule, cables permitted and listed for use in Class I Division 1 and Zone 1, and listed non-armored cables can be used in Class I Division 2 and Zone 2 hazardous locations.

e.g. Type TC (Tray Cable), Interlocked Armor cables

Cable Seals, Class I Division 2 & Zone 2

Where cables enter Class I Division 2 enclosures, the cable must be sealed if the enclosure contains any arcing or sparking devices or if the enclosure is explosion proof. In such cases a sealing fitting or Barrier gland to UL 2225 or CSA 22.2, Class I Division 1 or Division 2 must be used. Where the enclosure does not contain any arcing or sparking devices and the enclosure is NOT explosion proof, a cable is not required to be sealed at the point of entry. In such cases a listed cable gland or cable connector without compound sealing function may be used. e.g. CMP TMC, T3CDS or C2KX cable connectors.

Similarly for Class I Zone 1 & Zone 2 AEx e enclosures (Increased Safety), a non sealing fitting approved for use in this application can be used. e.g. CMP TMC, T3CDS or C2KX cable connectors.

Note : Non 'Sealing' type glands are restricted to Division 2 & Zone 2 equipment that does not contain an ignition source or to Zone 1 AEx e equipment. If the enclosure is required to be explosion proof, a Sealing fitting must be used.