General (Oregon)

General (Oregon Journeyman)

Learning Objectives

1.1 Article 90 — Use, Application, Arrangement, and Enforcement

Section 90.1: Article 90 covers the use and application, arrangement, and enforcement of the code; the expression of mandatory, permissive, and nonmandatory text; guidance on the examination of equipment and on wiring planning; and measurements. That is its subject — not definitions (Article 100), not general requirements for installations (Article 110), not wiring methods (Chapter 3).

Section 90.3: the introduction and nine chapters. Chapters 1 through 4 apply generally — General; Wiring and Protection; Wiring Methods and Materials; Equipment for General Use. Chapters 5 through 8 supplement or modify Chapters 1 through 8 — Specific Occupancies and Locations; Specific Equipment; Specific Conditions and Systems; Communications Systems. Chapter 9 is tables applicable as referenced; informative annexes are informational only.

1.2 Scope and Application of the Code (Section 90.2)

Covered, 90.2(A)(1): public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings; yards, lots, parking lots, carnivals, and industrial substations; conductors and equipment connecting to the supply of electricity; utility installations such as office buildings, warehouses, garages, machine shops, and recreational buildings that are not an integral part of a generating plant, substation, or control center; shore power to ships and watercraft in marinas and boatyards, including leakage-current monitoring.

Not covered, 90.2(A)(2): ships, watercraft other than floating buildings, railway rolling stock, aircraft, and vehicles other than mobile homes and recreational vehicles; underground mines; railway installations used exclusively for rolling stock or signaling and communications; communications equipment under the exclusive control of communications utilities outdoors; and installations under the exclusive control of an electric utility — service drops or laterals with metering, utility property, legally established easements or rights-of-way, and locations under written agreements recognized by public service commissions. That exclusion does not reach customer premises wiring.

Section 90.2(B): practical safeguarding of persons and property from hazards arising from the use of electricity, the code not being a design specification or an instruction manual for untrained persons. Section 90.2(C): compliance and proper maintenance give an installation essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion. Section 90.2(D): Section 131 of IEC 60364-1.

1.3 Enforcement, Interpretations, and the AHJ (Section 90.4)

Section 90.4(A): the code is suitable for mandatory application by governmental bodies that exercise legal jurisdiction over electrical installations, including signaling and communications systems, and for use by insurance inspectors. State adoption makes it enforceable, and enforcement runs through the electrical inspection authority having jurisdiction — in Oregon, the state electrical authority and the local jurisdiction that permits and inspects the work.

Section 90.4(B): the authority having jurisdiction for enforcement of the code makes interpretations of the rules, decides on the approval of equipment and materials, and grants the special permission contemplated in a number of the rules. Nobody else holds those powers — not the contractor, the journeyman, or the manufacturer.

Section 90.4(C): by special permission the AHJ may waive specific requirements or permit alternative methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety. Section 90.4(D): where the code requires new products not yet available at adoption, the AHJ may permit products complying with the most recent previous edition adopted by the jurisdiction.

1.4 Mandatory Rules, Permissive Rules, and Explanatory Material (Section 90.5)

"May", "should", "must", and "will" characterize neither rule class, and an informational note never becomes a requirement because an inspector or designer wants it to be one.

1.5 Article 100 — How the Definitions Work and Which Ones the Exam Tests

Article 100 holds only the definitions essential to the application of the code, and a definition followed by a parenthetical article reference applies only to that article. Accessible, readily accessible, approved, listed, and labeled are different concepts that distractors blur.

1.6 Approval, Listing, and Equipment Ratings (110.2 through 110.14)

Section 110.2: conductors and equipment required or permitted by the code shall be acceptable only if approved, and approved means acceptable to the authority having jurisdiction — so the installer carries the burden on unlisted equipment.

Section 110.3 governs examination, identification, listing, labeling, installation, and use: equipment shall be installed and used in accordance with any instructions included in the listing or labeling, and those instructions may be printed material, a quick response (QR) code, or an internet address. A marking of "indoor use only" is binding where the equipment may be installed.

Section 110.4: the voltage considered is that at which the circuit operates, and equipment voltage rating shall not be less than the nominal voltage of the circuit. Section 110.8: only wiring methods recognized as suitable are included in the code.

Section 110.10: OCPDs, equipment short-circuit current ratings, and other circuit characteristics shall be selected and coordinated with the available fault current so a fault is cleared without extensive damage, and listed equipment applied per its listing is deemed to meet this requirement.

Section 110.12: professional and skillful execution; unused openings closed to afford protection substantially equivalent to the wall of the equipment, with metallic plugs or plates on nonmetallic enclosures recessed at least 6 mm (1/4 in.); and busbars, terminals, and insulators free of damage or contamination. Section 110.14: terminations identified for the conductor material, no intermixing of dissimilar conductors unless the device is identified for it, and terminal connections torqued as indicated.

1.7 Interrupting Rating, Coordination, and Fault-Current Marking (110.9, 110.10, 110.24)

Section 110.9: equipment intended to interrupt current at fault levels shall have an interrupting rating at nominal circuit voltage at least equal to the available fault current at the line terminals of the equipment.

A device marked 10,000 amperes where 14,000 amperes are available at its line terminals is not acceptable standing alone: the fault current may not be rounded down Section 110.10 is the broader companion governing the equipment short-circuit current rating, cited when the rating of an assembly rather than a breaker is the subject.

Section 110.24(A): service equipment at other than dwelling units shall be legibly field-marked with the available fault current and the date the calculation was performed, complying with 110.21(B). Section 110.24(B): where modifications to the electrical installation affect the available fault current, that current must be recalculated and the marking adjusted to the new level, with the exception limited to industrial installations where only qualified persons service the equipment.

1.8 Markings: Equipment, Hazards, and Disconnecting Means (110.21 and 110.22)

Section 110.21(A): the manufacturer's name, trademark, or other descriptive marking identifying the responsible organization shall be applied onto all electrical equipment. Reconditioned equipment additionally carries the reconditioning organization, the date of reconditioning, and the term "reconditioned" or other approved wording, with the original listing mark removed or made permanently illegible. Section 110.21(B): field-applied hazard markings must be durable, warn of hazards by effective words, colors, symbols, or a combination, be permanently affixed to the equipment or wiring method, and not be handwritten — except variable portions, which must be legible.

Section 110.22(A): each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident, and outside one- and two-family dwellings the marking must also identify the circuit source and its location unless evident — so a disconnect not within sight of what it controls carries its own marking. Sections 110.22(B) and 110.22(C) require field marking of enclosures applied with engineered and with tested series combination ratings: a readily visible CAUTION label meeting 110.21(B) giving the system ampere rating and stating that identified replacement components are required.

1.9 Working Space at Equipment Not Over 1000 Volts (Section 110.26)

Section 110.26(A) applies to equipment likely to require examination, adjustment, servicing, or maintenance while energized — not to a voltage threshold, an outdoor location, feeder-only equipment, or monitored equipment. Open equipment doors must not impede access: access is impeded if simultaneously opened doors restrict it to less than 610 mm (24 in.) wide and 2.0 m (6 ft 6 in.) high at 90 degrees.

Condition 1 is live parts on one side with no live or grounded parts on the other, or live parts on both sides effectively guarded by insulating materials; Condition 2 is live parts on one side with grounded parts on the other, concrete, brick, and tile walls counting as grounded; Condition 3 is live parts on both sides. Depth is measured from the enclosure front or opening where live parts are enclosed, and from the live parts where exposed, with no working space required behind or beside dead-front assemblies whose connections and renewable or adjustable parts are accessible elsewhere and 762 mm (30 in.) horizontally required for rear access for non-electrical work. Width is the width of the equipment or 762 mm (30 in.), whichever is greater, with at least a 90-degree door opening. Height is clear to 2.0 m (6 ft 6 in.) or the height of the equipment, whichever is greater, with associated equipment above or below projecting not more than 150 mm (6 in.) beyond the front. Working space shall not be used for storage.

Entrances: at least one is required, not less than 610 mm (24 in.) wide and 2.0 m (6 ft 6 in.) high, and large equipment containing OCPDs, switching devices, or control devices rated 1200 amperes or more and over 1.8 m (6 ft) wide needs one at each end, with a single entrance permitted only for unobstructed egress or where the working-space depth is twice that required by 110.26(A)(1); personnel doors less than 7.6 m (25 ft) away must open 90 degrees in the direction of egress, and illumination is required with no automatic-means-only control.

Dedicated equipment space: service equipment, switchboards, switchgear, enclosed panelboards, and motor control centers must be in dedicated spaces, the indoor zone equal to the width and depth of the equipment and extending to 1.8 m (6 ft) above it being free of piping, ducts, leak protection, or foreign equipment, and outdoor equipment protected from accidental contact, vehicular traffic, and piping leakage.

1.10 Enclosure Types and "In Sight From" (110.28 and 110.29)

Section 110.28 requires the enclosures of switchboards, switchgear, enclosed panelboards, industrial control panels, motor control centers, and similar equipment, other than surrounding fences or walls, to be marked with an enclosure-type number as shown in Table 110.28, which selects them for specific locations other than hazardous (classified) locations. Type 1 handles incidental contact and falling dirt indoors; Type 3 adds rain, snow, sleet, and windblown dust; Type 3R handles rain but not windblown dust; Type 4 adds hosedown and splashing water with 4X corrosion resistance; Type 6 handles temporary submersion and 6P prolonged; Type 12 handles dust, lint, fibers, and flyings plus oil seepage.

Section 110.29: where equipment shall be in sight from, within sight from, or within sight of a building, structure, or other equipment, it shall be visible and not more than 15 m (50 ft) away. When a disconnect falls outside that envelope, 110.22 requires the disconnect itself to be marked with its purpose.

1.11 Over 1000 Volts, Nominal: Vaults, Entrances, and Working Space (110.30 through 110.34)

Section 110.31: an installation in a vault, room, or closet, or in an area surrounded by a wall, screen, or fence with access controlled by locks or other approved means, is accessible to qualified persons only. For installations other than equipment as described in 110.31(D), a wall, screen, or fence must enclose an outdoor installation: a fence not less than 2.1 m (7 ft) high, or at least 1.8 m (6 ft) of fabric plus a 300 mm (1 ft) or more extension of barbed wire, with fence-to-live-parts distances per Table 110.31.

Section 110.33(A): at least one entrance to enclosures for the installations described in 110.31, not less than 610 mm (24 in.) wide and 2.0 m (6 ft 6 in.) high; on switchgear and control panels exceeding 1.8 m (6 ft) in width, one entrance at each end, with a single entrance permitted only for a continuous and unobstructed exit or where the working space depth is twice that required by 110.34(A). Personnel doors less than 7.6 m (25 ft) from the working space must open 90 degrees in the direction of egress with listed panic or fire exit hardware. Section 110.33(C): the entrance to all buildings, vaults, rooms, or enclosures containing exposed live parts or exposed conductors shall be kept locked unless under the observation of a qualified person at all times, with permanent and conspicuous danger signs meeting 110.21(B) reading "DANGER — HIGH VOLTAGE — KEEP OUT".

Section 110.34(A): clear working space for equipment likely to require examination, adjustment, servicing, or maintenance while energized shall be not less than the depths of Table 110.34(A), measured from the live parts if exposed or from the enclosure front or opening if enclosed, with not less than 2.5 m (8 ft) horizontally in front of equipment in a passageway and 762 mm (30 in.) where rear access is needed for non-electrical work.

Table 110.34(A) is not interchangeable with Table 110.26(A)(1): the voltage ranges and depths differ. Section 110.34(B) requires permanent ladders or stairways for safe access to the working space around equipment on platforms, balconies, or mezzanine floors, or in attic or roof rooms.

Code Navigation

Common Exam Traps

Practical Field Points

Summary

Chapter 1 is the framework the rest of the code hangs on. Article 90 says how the code is used, arranged, and enforced: nine chapters, with Chapters 1 through 4 applying generally, Chapters 5 through 8 supplementing or modifying them, Chapter 9 supplying tables that apply as referenced, and the informative annexes carrying no requirements. Section 90.2 states what the code covers and what it does not and its purpose — the practical safeguarding of persons and property from hazards arising from the use of electricity — while the code is not a design specification or an instruction manual for untrained persons.

Article 100 supplies the vocabulary that decides close questions: accessible and readily accessible, approved, listed, labeled, live parts, dead-front, interrupting rating, available fault current, and current-limiting each mean something different. Article 110 applies that vocabulary to equipment: conductors and equipment must be approved, listed, labeled, and installed per their listing and instructions; unused openings must be closed to the equivalent of the wall of the equipment; connections must suit the conductor material and be torqued as instructed. The fault-current rules are quantitative — 110.9 sets the interrupting rating at the line terminals, 110.10 coordinates the OCPDs and short-circuit current ratings, and 110.24 field-marks the available fault current with its calculation date — and working space under 110.26, with its 2.0 m (6 ft 6 in.) headroom, width of the equipment or 762 mm (30 in.), depth from Table 110.26(A)(1) by voltage to ground and condition, entrances, illumination, and dedicated equipment space, plus the over-1000-volt rules in 110.30 through 110.34, completes the chapter.