Table #6 of the Canadian Electrical Code (CEC), 2006 edition makes references to RW90 with and without a jacket. Pages #285 and 286 show conduit fill for 600 volt and 1000 volt constructions without a jacket while pages 287 shows the fill for 600 volt constructions with a jacket.

C.S.A. Standard C22.2 #38 is the Part #2 standard that governs the construction of RW90. This standard allows the use of various types of insulation such as XLPE, EPR and EPCV. In the case of single conductor wire types R90, RW75, RW90, RWU75 and RWU90 manufactured with EPR or EPCV insulation, the present 2005 edition, requires a jacket or covering over the insulation. No such jacket is required for XLPE insulated wires of these types, but the standard still allows us to apply one.

CEC Rule #12-2202 covers the installation of cable in cable trays, and sub-rule #3 specifically covers the use of cables in electrical equipment vaults and service rooms, etc. This rule mentions that cables installed in these locations are required to have a moisture – resistant insulation, which all of the RW types of wires have, but also a "flame tested" non-metal covering, which regular XLPE insulated RW types do not have. This installation situation could arise where wires are installed in a conduit which then goes into an electrical room or vault, then onto tray to a transformer or some other piece of equipment. The duct portion of this run would have RW90 cables that would have an overall jacket and would therefore have to meet the conduit fill requirements shown for 600 volt RW90 with a jacket.

The normal RW types that all of us are familiar with probably have cross-linked polyethylene (XLPE) insulation but this insulation cannot be considered as flame retardant or flame tested. In order to make these products pass at least FT-1 for example they need to be made with a flame retardant non-metallic covering such as PVC.

Jackets or coverings over the insulation are added for mechanical reasons, as CSA Standard C22.2 #38 requires for EPR and EPCV. They may also be added to make the wire more flame retardant as in the case of XLPE. Regardless of the reason they are added an overall jacket increases the outside diameter of the wire. That’s why you see a larger outside diameter for these jacketed types in Table #10 and that’s why less wires of the same size are allowed in the same conduit in Table #6. Table #6 is based on 40% conduit fill as required by Table #8 so if a wire or cable has a larger diameter, less of them can go into a given sized conduit.

EPR and EPCV RW types as well as an XLPE RW type with a PVC jacket, are still allowed by the C.S.A. standard. However their use in the field is virtually non-existent. Basically you should use only the sections in Tables #6 and #10 that deal with 600 volt R and RW types without a jacket. Sections dealing with jacketed types cannot be deleted from the tables because C.S.A. Standard C22.2 #38 still allows wires of these types.

Information on 600 volt RW90, 1000 volt RW90 and 1000 volt RWU90 is shown in our Building Wire and Corflex II catalogue.

By : D.S. Reith, C.E.T. – Applications Specialist, Equipment Cables

Technical Bulletin #1, Rev #1 - January 24, 2006