Philippine Electrical Code 2017 Part 1/Chapter 3. Wiring Methods and Materials/Article 3.0 - Wiring Methods/3.0.2 Requirements for Over 600 Volts, Nominal

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3.0.2 Requirements for Over 600 Volts, Nominal

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This is not an official copy of the Philippine Electrical Code. This is a Design Guide according to the provisions of the Philippine Electrical Code. It also provides interpretation and annotations of the clauses of the Philippine Electrical Code. Any information, interpretation and/or annotation presented herein are based on personal opinion of the authors and does not represent the official interpretation of the Philippine Electrical Code.


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3.0.2 Requirements for Over 600 Volts, Nominal

3.0.2.1 Covers Required.

Suitable covers shall be installed on all boxes, fittings, and similar enclosures to prevent accidental contact with energized parts or physical damage to parts or insulation.

3.0.2.2 Conductors of Different Systems. See 3.0.1.3(c)(2).

3.0.2.4 Conductor Bending Radius.

The conductor shall not be bent to a radius less than 8 times the overall diameter for nonshielded conductors or 12 times the overall diameter for shielded or lead- covered conductors during or after installation. For multiconductor or multiplexed single conductor cables having individually shielded conductors, the minimum bending radius is 12 times the diameter of the individually shielded conductors or 7 times the overall diameter, whichever is greater.

3.0.2.5 Protection Against Induction Heating.

Metallic raceways and associated conductors shall be arranged so as to avoid heating of the raceway in accordance with the applicable provisions of 3.0.1.20.

3.0.2.7 Aboveground Wiring Methods.

Aboveground conductors shall be installed in rigid metal conduit, in intermediate metal conduit, in electrical metallic tubing, in rigid nonmetallic conduit, in cable trays, as busways, as cablebus, in other identified raceways, or as exposed runs of metal-clad cable suitable for the use and purpose. In locations accessible to licensed electrical practitioner or non licensed electrical practitioner under the supervision of a licensed electrical practitioner only, exposed runs of Type MV cables, bare conductors, and bare busbars shall also be permitted. Busbars shall be permitted to be either copper or aluminum.

3.0.2.9 Braid-Covered Insulated Conductors — Exposed Installation.

Exposed runs of braid-covered insulated conductors shall have a flame-retardant braid. If the conductors used do not have this protection, a flame-retardant saturant shall be applied to the braid covering after installation. This treated braid covering shall be stripped back a safe distance at conductor terminals, according to the operating voltage. Where practicable, this distance shall not be less than 25 mm for each kilovolt of the conductor-to-ground voltage of the circuit.

3.0.2.10 Insulation Shielding.

Metallic and semiconducting insulation shielding components of shielded cables shall be removed for a distance dependent on the circuit voltage and insulation. Stress reduction means shall be provided at all terminations of factory- applied shielding.

Metallic shielding components such as tapes, wires, or braids, or combinations thereof, and their associated conducting or semiconducting components shall be grounded.

3.0.2.12 Moisture or Mechanical Protection for Metal-Sheathed Cables.

Where cable conductors emerge from a metal sheath and where protection against moisture or physical damage is necessary, the insulation of the conductors shall be protected by a cable sheath terminating device.

3.0.2.20 Underground Installations.

(a) General.

Underground conductors shall be identified for the voltage and conditions under which they are installed. Direct burial cables shall comply with the provisions of 3.10.1.7. Underground cables shall be installed in accordance with 3.0.2.20(a)(1) or (a)(2), and the installation shall meet the depth requirements of Table 3.0.2.20.

(1) Shielded Cables and Nonshielded Cables in Metal-Sheathed Cable Assemblies.

Underground cables, including nonshielded, Type MC and moisture-impervious metal sheath cables, shall have those sheaths grounded through an effective grounding path meeting the requirements of 2.50.1.4(a)(5) or (b)(4). They shall be direct buried or installed in raceways identified for the use.

(2) Other Nonshielded Cables.

Other nonshielded cables not covered in 3.0.2.20(a)(1) shall be installed in rigid metal conduit, intermediate metal conduit, or rigid nonmetallic conduit encased in not less than 75 mm of concrete.

Table 3.0.2.20 Minimum Cover1 Requirements
Circuit Voltage General Conditions (not otherwise specified) Special Conditions (use if applicable)
(1)
Direct-Buried Cables
(mm)
(2)
Rigid Nonmetallic Conduit2
(mm)
(3)
Rigid Metal Conduit and Intermediate Metal Conduit
(mm)
(4)
Raceways under buildings or exterior concrete slabs, 100mm minimum thickness3
(mm)
(5)
Cables in airport runways or adjacent areas where trespass is prohibited
(mm)
(6)
Areas subject to vehicular traffic, such as thoroughfares and commercial parking areas
(mm)
Over 600 V through 22 kV 760 460 150 100 450 600
Over 22 kV through 40 kV 900 600 150 100 450 600
Over 40 kV 1000 760 150 100 450 600
Notes:
1. Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required.
2. Where solid rock prevents compliance with the cover depths specified in this table, the wiring shall be installed in a metal or nonmetallic raceway permitted for direct burial. The raceways shall be covered by a minimum of 50 mm of concrete extending down to rock.
1 Cover is defined as the shortest distance in millimeters measured between a point on the top surface of any direct-buried conductor, cable, conduit, or other raceway and the top surface of finished grade, concrete, or similar cover.
2 Listed by a qualified testing agency as suitable for direct burial without encasement. All other nonmetallic systems shall require 50 mm of concrete or equivalent above conduit in addition to the table depth.
3 The slab shall extend a minimum of 150 mm beyond the underground installation, and a warning ribbon or other effective means suitable for the conditions shall be placed above the underground installation.


(b) Protection from Damage.

Conductors emerging from the ground shall be enclosed in listed raceways. Raceways installed on poles shall be of rigid metal conduit, intermediate metal conduit, PVC Schedule 80, or equivalent, extending from the minimum cover depth specified in Table 3.0.2.20 to a point 2 400 mm above finished grade. Conductors entering a building shall be protected by an approved enclosure or raceway from the minimum cover depth to the point of entrance. Where direct-buried conductors, raceways, or cables are subject to movement by settlement or frost, they shall be installed to prevent damage to the enclosed conductors or to the equipment connected to the raceways. Metallic enclosures shall be grounded.

(c) Splices.

Direct burial cables shall be permitted to be spliced or tapped without the use of splice boxes, provided they are installed using materials suitable for the application. The taps and splices shall be watertight and protected from mechanical damage. Where cables are shielded, the shielding shall be continuous across the splice or tap. Exception: At splices of an engineered cabling system, metallic shields of direct-buried single-conductor cables with maintained spacing between phases shall be permitted to be interrupted and overlapped. Where shields are interrupted and overlapped, each shield section shall be grounded at one point.

(d) Backfill.

Backfill containing large rocks, paving materials, cinders, large or sharply angular substances, or corrosive materials shall not be placed in an excavation where materials can damage or contribute to the corrosion of raceways, cables, or other substructures or where it may prevent adequate compaction of fill. Protection in the form of granular or selected material or suitable sleeves shall be provided to prevent physical damage to the raceway or cable.

(e) Raceway Seal.

Where a raceway enters from an underground system, the end within the building shall be sealed with an identified compound so as to prevent the entrance of moisture or gases, or it shall be so arranged to prevent moisture from contacting live parts.

Other Pages in this Category: Chapter 3. Wiring Methods and Materials

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