Resolución 2535: adopta el Código Eléctrico Nacional, versión 1993. (Sustituye el Anejo A del Reglamento 4435)

(h) Exposed and Accessible. Cable trays shall be exposed and accessible except as permitted by Section 318-6(g). (i) Adequate Access. Sufficient space shall be provided and maintained about cable trays to permit adequate access for installing and maintaining the cables. (FPN): See Section 310-10 for temperature limitation of conductors. (j) Incidental Support from Cable Tray. Where approved and designed to support the load, cable trays shall be permitted as a means of incidental support for raceways that are supported in accordance with Articles 345, 346, 347, and 348. (FPN): See Section 300-11(b) for restrictions concerning raceways used as a means of support. 318-7. Grounding. (a) Metallic Cable Trays. Metallic cable trays that support electrical conductors shall be grounded as required for conductor enclosures in Article 250. (b) Steel or Aluminum Cable Tray Systems. Steel or aluminum cable tray systems shall be permitted to be used as equipment grounding conductors provided that all the following requirements are met: (1) The cable tray sections and fittings shall be identified for grounding purposes. (2) The minimum cross-sectional area of cable trays shall conform to the requirements in Table 318-7(b)(2). (3) All cable tray sections and fittings shall be legibly and durably marked to show the cross-sectional area of metal in channel cable trays, or cable trays of one-piece construction, and the total cross-sectional area of both side rails for ladder or trough cable trays. (4) Cable tray sections, fittings, and connected raceways shall be bonded in accordance with Section 250-75 using bolted mechanical connectors or bonding jumpers sized and installed in accordance with Section 250-79. ARTICLE 318 - CABLE TRAYS 70-201 Table 318-7(b)(2). Metal Area Requirements for Cable Trays Used as Equipment Grounding Conductors Maximum Fuse Ampere Rating, Circuit Breaker Ampere Trip Minimum Cross-Sectional Area of Setting, or Circuit Breaker Protective Relay Ampere Trip Metal* in Square Inches Setting for Ground-Fault Protection of Any Cable Circuit Steel Aluminum in the Cable Tray System Cable Trays Cable Trays 60 0.20 0.20 100 0.40 0.20 200 0.70 0.20 400 1.00 0.40 600 1.50** 0.40 1000 - 0.60 1200 - 1.00 1600 - 1.50 2000 - 2.00** For SI units: one square inch = 645 square millimeters. *Total cross-sectional area of both side rails for ladder or trough cable trays; or the minimum cross-sectional area of metal in channel cable trays or cable trays of one-piece construction. **Steel cable trays shall not be used as equipment grounding conductors for circuits with ground-fault protection above 600 amperes. Aluminum cable trays shall not be used as equipment grounding conductors for circuits with ground-fault protection above 2000 amperes. 318-8. Cable Installation. (a) Cable Splices. Cable splices made and insulated by approved methods shall be permitted to be located within a cable tray provided they are accessible and do not project above the side rails. (b) Fastened Securely. In other than horizontal runs, the cables shall be fastened securely to transverse members of the cable trays. (c) Bushed Conduit and Tubing. A box shall not be required where cables or conductors are installed in bushed conduit and tubing used for support or for protection against physical damage. (d) Connected in Parallel. Where single conductor cables comprising each phase or neutral of a circuit are connected in parallel as permitted in