Oklahoma Residential Electrical Journeyman

Mandatory rules identify actions specifically required or prohibited and are characterized by "shall" or "shall not," while Informational Notes are informational only and are not enforceable as Code requirements.

Chapters 1 through 4 apply generally to all electrical installations, whereas Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify Chapters 1 through 4.

Chapter 8 is not subject to the requirements of Chapters 1 through 7 except where those requirements are specifically referenced in Chapter 8.

SI units are the Code's measurement system of preference and shall appear first, with inch-pound units immediately following in parentheses.

Both sizes may be identified by a continuous white or gray outer finish or by three continuous white or gray stripes on other than green insulation; the key difference is that 4 AWG or larger may instead be identified at the time of installation by a distinctive white or gray marking encircling the insulation at its terminations.

Grounded conductors and their terminals are identified white, gray, or silver (or "white"/"W"), while green or green with one or more yellow stripes is reserved for equipment grounding conductors and shall not be used for anything else.

A white or gray conductor may serve as an ungrounded conductor in circuits of 50 volts or more only where it is part of a cable assembly and is permanently reidentified (tape, paint, or other effective means in a color other than white, gray, or green) at its termination and at each location where the conductor is visible and accessible; without that marking it is not permitted.

The 125 percent multiplier applies only to the continuous load portion, which is added to the noncontinuous load at 100 percent when sizing branch-circuit conductors and overcurrent devices.

Both use noncontinuous load plus 125 percent of continuous load, but 210.20(A) applies to branch circuits and 215.3 applies to feeders, with the result rounded to a standard rating from 240.6(A).

Where it does not extend to other electrode types requiring a larger conductor, the GEC to a rod/pipe/plate electrode need not be larger than 6 AWG copper (4 AWG aluminum), while to a concrete-encased electrode it need not be larger than 4 AWG copper.

Aluminum has roughly 1.6 times the resistance of copper, so its higher K value produces a larger calculated voltage drop for the same size, current, and length.

Series resistances add directly, while parallel resistance is found by product-over-sum (or reciprocals) and is always less than the smallest branch resistance.

On circuits exceeding 120 volts between conductors but not exceeding 277 volts to ground, incandescent luminaires are permitted only with medium-base or smaller lampholders supplied at 120 volts or less through an integral auto/stepdown transformer; mogul-base lampholders supplied at 240 volts are not permitted.

RMC, IMC, rigid nonmetallic conduit, and EMT are exempt from the steel plate protection requirement in notches, while other wiring methods such as cables require the steel plate.