1. National Electrical Code Article 310
3/31/2017 1:24 PM
National Electrical Code Article 310
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2. Conductors for General Wiring
(A) Insulated - Conductors Shall be Insulated
Exception: Where covered or bare conductors are specifically permitted else where in this code.
(B) Conductor Material. – Conductors in this article shall be of aluminum, copper – clad aluminum, or copper unless otherwise specified.
310.3 Stranded Conductors
Where installed in raceways, conductors of size 8 AWG and larger shall be stranded.
Exception: As permitted or required elsewhere in this Code.

3. Conductors for General Wiring
Locations
(A) Dry Locations. – Insulated conductors and cables used in dry locations shall be any of the types identified in this Code.
(B) Dry and Damp Locations. – Insulated conductors and cables used in dry and damp locations shall be Types FEP, FEPB, MTW, PFA, RHH, RHW, RHW-2, SA, THHN, THW, THW-2, THHW, THWN, THWN-2, TW, XHH, XHHW, XHHW – 2, Z, OR ZW.

4. Conductors for General Wiring
Locations (cont.’d)
(C) Wet Locations. – Insulated conductors and cables used in wet locations shall comply with one of the following:
Be moisture – impervious metal – sheathed
Be types MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW.
Be of a type listed for use in wet locations.

5. Conductors for General Wiring
Locations (cont.’d)
(D) Locations Exposed to Direct Sunlight. – Insulated conductors or cable used where exposed to direct rays of the sun shall comply with:
Conductors and cables shall be listed, or listed and marked, as being sunlight resistant.
Covered with insulating material, such as tape or sleeving, that is listed, or listed and marked, as being sunlight resistant
This material was extracted from Mike Holt Training Materials copyright 2007 by permission. Visit mikeholt.com or call NEC.CODE ( ) for more information.

6. Conductors for General Wiring
310.9 Corrosive Conditions. -
Conductors exposed to oils, greases, vapors, gases, fumes, liquids, or other substances having a deleterious effect on the conductor or insulation shall be of a type suitable for the application.

7. Conductors for General Wiring
Temperature Limitation of Conductors.
No conductor shall be used in such a manner that its operating temperature exceeds that designated for the type of insulated conductor involved. In no case shall conductors be associated together in such a way, with respect to type of circuit, the wiring method employed, or the number of conductors, that the limiting temperature of any conductor is exceeded.

8. Conductors for General Wiring
Temperature Limitation of Conductors
This material was extracted from Mike Holt Training Materials copyright 2007 by permission. Visit mikeholt.com or call NEC.CODE ( ) for more information.

9. Conductors for General Wiring
Marking.
(A) Required Information. All conductors and cables shall be marked to indicate the following information, using the applicable method described in (B):
(1) The maximum rated voltage.
(2) The proper type letter or letters for the type of wire or cable as specified elsewhere in this Code.
(3) The manufacturer's' name, trademark, or other distinctive marking by which the organization responsible for the product can be readily identified.
(4) The A W G size or circular mil area.
(5) Cable assemblies where the neutral conductor is smaller than the ungrounded conductors shall be so marked.

10. Conductors for General Wiring
Conductor Constructions and Applications.
Insulated conductors shall comply with the applicable provisions of Table , , , and

11. Conductors for General Wiring
Table Provides useful information about wire styles and uses.

12. Conductors for General Wiring
Voltage drop can occur when wire sizing is not considered.
E = I X R
Voltage = Amp times Resistance
#10 wire = ,000 feet
15 v = 15 Amp x 1.00 ohm
115v – 15v = 100v

13. Conductors for General Wiring
Adjustment for temperature exposure and wiring limit within a conduit.
This material was extracted from Mike Holt Training Materials copyright 2007 by permission. Visit mikeholt.com or call NEC.CODE ( ) for more information.

14. Conductors for General Wiring
Ampacities for Conductors Rated 0 – 2000 volts
(1) Tables or Engineering Supervision.
Ampacities for conductors shall be permitted to be determined by tables or under engineering supervision, as provided in (b) and (c).
(2) Selection of Ampacity.
Where more than one calculated or tabulated ampacity could apply for a given circuit length, the lowest value shall be used.

15. Conductors for General Wiring
Ampacities for Conductors (cont.’d)
(B) Tables.
Ampacities for conductors rated 0 – 2000 volts shall be as specified in the Allowable Ampacity Table through and Ampacity Table through as modified by (1) through (6).
(2) Adjustment Factors.
(a) More Than Three Current – Carrying Conductors in a Raceway or Cable. Where the number of current – carrying conductors in a raceway or cable exceeds three, or where single conductors or multcondutor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table (b)(2)(a).

16. Conductors for General Wiring
Table

17. Conductors for General Wiring
Use Table (b)(2)(a) to adjust current carrying capacity more than 3 conductors share the same raceway or conduit.

18. Conductors for General Wiring
When the exposure temperature exceeds 86º F then a correction factor is applied.

19. Conductors for General Wiring
Ampacities for Conductors (cont.’d)
(3) Bare or Covered Conductors.
Where bare or covered conductors are used with insulated conductors, their allowable ampacities shall be limited to those permitted for the adjacent insulated conducts.
(4) Neutral Conductor
(a) A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of (b)(2)(a).

20. Conductors for General Wiring
Ampacities for Conductors (cont.’d)
(5) Grounding or Bonding Conductor. A grounding or bonding conductor shall not be counted when applying the provisions of (b)(2)(a)