Conductors that do not have hazardous potentials and that do not directly control potential safety hazards are exempt from the requirements of this section.
1. Conductor size - Conductor size used in power or control circuits shall not be smaller than #18 AWG.
2. Separation - All conductors within a harness, wireway, or raceway shall have insulation rated for use at the highest potential present.
3. Parallel conductors - Conductors shall not be paralleled to provide required ampacity.
4. Temperature - Conductors shall not be exposed to temperatures greater than 90 % of their rating,
5. Insulation - Conductor insulation shall be continuous and undamaged between terminations.
6. Installation - Installation of conductors shall comply with wiring methods of Sec 9.
7. Identification
a. Each conductor shall be identified by a number, letter, or number-letter combination.
b. All common circuit conductors shall have the same identification at all terminals and termination points.
c. The identification shall not be used in more than one circuit.
Refer to the National Electrical Codeã , Article 310.
4.2.1 MTW (THHN / THWN). Type MTW or equivalent conductors.
1. Minimum Requirements:
- #18 AWG.
-Stranded copper.
-600 V, 90 ° C (194 ° F) rated insulation.
2. Uses - Suitable for all circuits unless special insulation or shielding is required.
4.2.2 E, EE, K, KK. Type E, EE, K, KK or equivalent conductors.
1. Minimum requirements:
- # 18 AWG.
- Stranded copper, nickel or silver coated.
-600 V, 90 ° C (194 ° F) rated teflon insulation.
2. Suitable only for hookup wire within control enclosures; not suitable for installation in raceways.
3. Installation - must be laced harnessed or installed in nonmetallic wireways.
4.2.3 Marking. Conductors shall be durably marked on the surface at intervals not exceeding 24 inches.
1. The maximum rated voltage for which the conductor was listed.
2. The proper type letters or letters for the conductor.
3. The manufacturer’s name or trademark.
4. The size of the conductor in circular mils or AWG.
4.2.4 Ampacity. Conductors shall be protected for their ampacity rating by circuit protection devices sized according to the table and notes in Table 10.
4.2.5 Derating. The maximum ampacity of conductors shall be derated according to the number of conductors installed in a bundle, harness, stack, raceway, wireway or wiring duct. See Table 10.
4.2.6 Fill. Conductors installed in raceways, wireways, and wiring ducts shall comply with the following:
1. Raceways - The sum of the cross-sectional areas of all contained conductors shall not exceed 25 % of the interior cross-sectional area of the raceway.
EXCEPTION: Raceway fill may increase to 40 % when modifying existing equipment.
2. Wireways - The sum of the cross-sectional areas of all contained conductors shall not exceed 20 % of the interior cross-sectional area of the wireway.
3. Plastic wiring ducts - The sum of the cross-sectional areas of all contained conductors shall not exceed 50 % of the interior cross-sectional area of the wiring duct.
See the National Electrical Codeã , Article 400.
4.3.1 Types SJ, SJO, SJT, SJTO. Types SJ, SJO, SJT, and SJTO cords and cables with 300 V, 60 ° C (140 ° F) rated insulation are restricted to:
1. 120 V circuits protected for 10 A or less.
2. #16 or #18 AWG wire.
3. No more than two current carrying conductors.
4.3.2 Types SVT, SVTO, SVO. Types SVT, SVTO, and SVO cords and cables with 300 V, 60 ° C (140 ° F) rated insulation are restricted to:
1. 120 V circuits protected for 10 A or less.
2. #16 or #18 AWG wire.
3. No more than two current carrying conductors.
4. Use - Counter top or rack mounted equipment.
4.3.3 Types S, SO, ST, STO. Types S, SO, ST, and STO cords and cables with 600 V, 60 ° C (140 ° F) rated insulation are restricted to the:
1. Uses permitted by 4.3.7.
2. Ampacity permitted by Table 13.
4.3.4 Suitability. Flexible cords and cables shall be suitable for the conditions of use and location per the National Electrical Codeã , Article 400 and / or manufacturer’s recommended use.
4.3.5 Marking. Flexible cords and cables shall be durably marked on the surface at intervals not exceeding 24 inches to indicate:
1. Type designation.
2. Number of conductors.
3. Size.
4.3.6 Color Code. Flexible cords and cables shall comply with Table 14.
4.3.7 Uses Permitted. Flexible cords and cables are permitted:
1. When equipped with an attachment plug and powered from an accessible receptacle outlet:
a. To connect movable equipment to facilitate frequent interchange.
b. When fastening means and mechanical connection of equipment are designed to permit removal for maintenance or repair.
2. When not equipped with an attachment plug, to prevent transmission of noise or vibration.
4.3.8 Uses Not Permitted. Flexible cords and cables:
1. Shall not be used for internal machine wiring.
2. Shall not be used as an extension cord.
3. Shall not be used as a substitute for fixed wiring.
4. Shall not be used to connect stationary equipment to a power source.
4.3.9 Restrictions. Flexible cords and cables:
1. Shall not be attached to equipment surfaces.
2. Shall not be coiled, but shall be of the shortest feasible length, not to exceed 8 ft.
3. Shall not have any splices.
4. Shall not be inaccessible.
5. Shall not run through unprotected holes.
6. Shall be installed in protected (bushed) holes that are large enough to allow cord connector (attachment plug) passage.
7. Shall have strain relief at terminations to connectors or equipment that will prevent any mechanical stress on the cord from being transmitted to the conductors or terminals.
See 6.8.
4.4 Multiconductor (Jacketed) Cables.
4.4.1 Description. Multicolor electronic wire and cable, such as communication and control cable, instrumentation cable, electrical cable, and computer cable; some have shields, many have PVC insulated jackets.
4.4.2 Restrictions. The following types of cable are not acceptable for equipment wiring:
1. Armored Cable (AC).
2. Integrated Gas Spacer Cable (IGS).
3. Flat Conductor Cable (FCC).
4. Mineral-Insulated, Metal-Sheathed Cable (MI).
5. Metal-Clad Cable (MC).
6. Non-Metallic Sheathed Cable (NM or NMC).
7. Shielded Non-Metallic Sheathed Cable (SNM)
8. Service Entrance Cable (SE or USE).
9. Underground Feeder or Branch Circuit Cable (UF).
Notes:
1. See National Electrical Codeã for definitions.
2. BX and ATC are a type of Armored Cable (AC).
4.4.3 Marking. Shall be marked with the manufacturer name and part number or the following data:
1. Maximum Rated Voltage.
2. Type.
3. Temperature Rating.
4. Size.
4.4.4 Power Usage. If multiconductor cable is used for power circuits (greater than 100 V ), the insulation shall be rated for at least 600 V, 80 ° C (176 ° F).
4.4.5 Connectors. Multiconductor cable connectors used in circuits having hazardous potentials shall meet all the requirements of Section 3.7.
Conductive metal connectors shall comply with Section 5.5.
4.4.6 Color Code. Shall comply with the following requirements:
1. Multiconductor cables used for power circuits shall comply with Table 14.
2. Multiconductor cables used for control circuits shall have color code identified on drawings. See 2.3.1.
Other conductors installed in equipment shall comply with the requirements of the National Electrical Codeã .
4.5.1 Insulation. When required by ambient conditions, appropriate conductor insulating material shall be used. For example, conductors installed on or adjacent to heat generating equipment (e.g., furnaces, ovens) shall have UL approved, type AVA, SFF2, or equivalent insulation.
4.5.2 Bus Bars (Noninsulated). Noninsulated bus bars shall be sized according to Table 15 which is based on the following:
1. Material - copper @ 98 % conductivity.
2. Temperature - 40 ° C (104 ° F) ambient.
3. Spacing - See Article 384 of the National Electrical Codeã .
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