13.6 WAC 296-46B Amendments: Adoption, General Rules, Services, Grounding & Wiring (NEC Chapters 1-4)
Key Takeaways
- WAC 296-46B-010 adopts the 2023 NEC (effective April 1, 2024) and makes the 2026 NEC effective December 31, 2026; the WAC controls wherever it conflicts with the adopted standards.
- When the service disconnect is inside a building, the service raceway may extend no more than 15 feet inside, unless the conductors have customer-owned supply-side overcurrent protection (WAC 296-46B-230(10)).
- Service conductors inside a building are limited to rigid or intermediate metal conduit, Schedule 40 or heavier PVC, wireways, busways, auxiliary gutters, cablebus, or Type MI cable (WAC 296-46B-230(7)).
- A concrete-encased electrode must be installed and used at each new building on a permanent concrete foundation, except mobile or manufactured homes (WAC 296-46B-250(2)).
- In Washington, NM-B conductors larger than 10 AWG may use the 75 degree C ampacity, and water heaters over 3,500 watts at 208 or 240 volts need at least 10 AWG copper (WAC 296-46B-334, -422).
Last updated: September 2026
How Washington adopts the NEC (WAC 296-46B-010)
- Adopted edition: the 2023 NEC (with Annexes A, B, and C and later errata and tentative interim amendments), plus the ANSI/TIA-568, -569, -607, and -570 telecommunications standards and the National Electrical Safety Code. This took effect April 1, 2024.
- Next edition: the 2026 NEC is adopted effective December 31, 2026.
- Precedence: WAC 296-46B controls wherever it conflicts with the adopted standards. The NEC controls over the TIA standards and the NESC.
- Which edition applies to a job: the one in effect on the date the electrical permit is issued. New dwellings whose building permit was issued earlier, and plan review projects accepted earlier, stay on the older edition.
Exam caution: the PSI bulletin (10/30/2025) and L&I's exam page still base code questions on the 2020 NEC, while Washington questions follow the current RCW 19.28 and WAC 296-46B. WAC amendments cite 2023 NEC section numbers, so a few may not match your 2020 book exactly.
Other general rules in -010:
- A variance may be granted when equivalent safety is achieved. The permit holder requests it in writing with the fee (-010(3)).
- Equipment must be listed or field evaluated to a standard recognized by L&I before it is energized (-010(7)).
- Lawful existing installations may stay unchanged. Additions and alterations must meet current rules (-010(14)).
- Educational and institutional facilities must be wired in metallic or nonmetallic raceways or Type MI, MC, or AC cable (-010(12)).
General requirements (WAC 296-46B-110)
- Flooded equipment: breakers, fuses, controllers, receptacles, switches, heaters, and sealed devices that were submerged must be replaced. Other flooded equipment must be replaced or reconditioned by the manufacturer.
- Disconnect identification (NEC 110.22): an identification plate is required unless the disconnect is a breaker or fused switch identified on the panel schedule. In other than dwelling units, the plate names the source panelboard.
- Cables over 1,000 V must be permanently marked with phase, operating voltage, and circuit number at each termination and accessible point.
Branch circuits, feeders, and calculations (-210, -215, -220, -225)
| Amendment | Rule |
|---|---|
| -210 GFCI, dwellings | A red receptacle with a red cover supplying only a fire alarm system in a garage or unfinished basement needs no GFCI, if identified with 1/4-inch letters. Fixed equipment with exposed grounded metal inside an enclosed shower, or within 5 ft of the top inside edge of a tub, needs GFCI. |
| -210 GFCI, other occupancies | Three-phase receptacles need GFCI only where required elsewhere in the NEC. For NEC 210.8(B), a kitchen is any area where utensils or dishes are cleaned or food or beverages are prepared or cooked. |
| -210 unfinished space | A raceway or a dedicated 15 A, 120 V circuit must reach unfinished dwelling space adaptable to future living area: one for each 480 sq ft or less |
| -210 receptacle spacing | Window seats and floor-to-5-ft-6-in bookcases count as "similar openings." Outlets they eliminate must be installed elsewhere in the room. |
| -210 islands | If no receptacle serves an island or peninsula, no future provision is required |
| -215 feeders | A one-line diagram is required for nondwelling services or feeders over 400 A or over 600 V. A feeder smaller than its equipment rating gets a "Feeder conductor ampacity" plate. Equipment ground-fault protection must be performance tested. |
| -220 | A building designed to the Washington State Energy Code's lighting power allowance may use it in place of NEC 220.42 |
| -225 | An outside feeder disconnect counts as "in the building" if it is on the building or within sight and within 15 ft. It needs a plate with half-inch letters naming the building and its function. Roof clearance may be 3 ft where the voltage between conductors is 300 V or less and the roof is guarded or isolated. |
Services (WAC 296-46B-230): the most tested amendments
- Utility first: consult the serving utility about meter and service location before installing.
- Masts: drops with conductors larger than #1 aluminum or #3 copper need galvanized rigid steel conduit no smaller than 2 inches. Smaller drops need at least 1-1/4 inches. Guy the mast if the drop attaches more than 24 inches above the roof line or the span exceeds 100 feet. Leave at least 18 inches of conductor out of the masthead.
- Wiring methods inside the building: service conductors of 1,000 V or less inside a building are limited to galvanized or aluminum RMC, galvanized IMC, wireways, busways, auxiliary gutters, Schedule 40 or heavier PVC, cablebus, or Type MI cable. EMT and SE cable are not on the list. The exception is conductors with customer-owned supply-side overcurrent protection sized per NEC 240.4.
- Grounded conductor color: in addition to the NEC methods, the grounded service conductor may be identified with a yellow jacket or yellow stripes.
- Disconnect location:
- Outside: on the building or within sight and within 15 feet of it, with a half-inch-letter plate naming the building and its function. It may supply only that one building.
- Inside: located so the service raceway extends no more than 15 feet inside the building. No length limit applies with customer-owned supply-side overcurrent protection.
- Emergency disconnect on replacement (replaces NEC 230.85(C)): when a one- or two-family dwelling's service equipment is replaced, an emergency disconnect is required if the service ampacity changes, or if the disconnect, meter base, mast, or underground riser is relocated.
- Service conductor ampacity plate: required on other-than-dwelling services up to 400 A when conductors are smaller than the equipment or overcurrent rating.
- Ground-fault protection testing by a qualified firm, with a signed test record available at inspection.
Overcurrent protection (WAC 296-46B-240)
- Outdoor enclosures containing overcurrent devices must have their bottom at least 24 inches above finished grade, unless listed for pad or ground mounting or set over paving that extends 3 ft or more from the enclosure.
- A panelboard repaired or replaced in an existing location may remain over steps.
- For fuses and circuit breakers of 1,200 A and higher, arcing-current calculations and a written arc energy reduction test report must be available at inspection.
Grounding and bonding (WAC 296-46B-250)
- Concrete-encased electrode required: every new building or structure on a permanent concrete foundation (except mobile or manufactured homes) must have an NEC 250.52(A)(3) electrode installed and used. It is inspected visually, by a continuity lead spanning at least 20 ft, or by another approved method. If no such electrode is available, install a ground ring, or another electrode that an independent firm tests at 25 ohms or less.
- Rods, pipes, or plates: without a resistance test showing 25 ohms or less, install two or more electrodes at least 6 ft apart. A temporary construction service needs only one. Adjacent buildings' electrodes must be at least 6 ft apart.
- A grounding electrode conductor is considered protected when buried more than 12 inches deep outside the building footprint, covered by 2 inches of concrete or asphalt, protected inside the footprint by the structure, or in a raceway.
- Flexible metal gas piping (CSST): follow the manufacturer's bonding instructions, or use at least 6 AWG copper from a listed connector at the gas meter end to the service equipment, grounding electrode conductor, electrode, or neutral bus.
- Hot and cold water lines joined by a metallic mixing valve need no separate bonding jumper. Metal stubs in nonmetallic plumbing need no bonding unless the manufacturer requires it.
Wiring methods and equipment (-300 to -450)
| WAC | Washington rule |
|---|---|
| -300 | Class 2 and Class 3 cables must follow NEC Chapter 3. Telecommunications and optical fiber cables must be supported at intervals not exceeding 5 ft. Ceiling support wires may carry raceways or cables only under listed conditions (3/4-inch trade size or smaller, at most two per wire, #12 minimum support wire). |
| -314 | Boxes and conduit bodies must be accessible without removing any building structure, including insulation. Pendant-box cords may be at most 6 ft, at least 14 AWG copper, hard or extra-hard usage. For NEC 314.27(C), the habitable-room ceiling areas treated as likely paddle-fan locations exclude areas within 4 ft of walls, soffits, or fixed cabinetry and areas above island or peninsula countertops. |
| -334 | In multifamily and other structures of Types III, IV-HT, and V, NM may be used as the WAC allows. NM-B ampacity: 10 AWG and smaller at the 60 degree C column; larger than 10 AWG at the 75 degree C column; the 90 degree C rating may be used for adjustment and correction. NM may run in short outdoor sleeves under four conditions (10 ft or less, above grade, sealed, no flexible metal conduit). |
| -358 | EMT may not be in direct contact with the earth or in concrete on or below grade. EMT in wet locations needs a wire-type equipment grounding conductor. |
| -394 | Loose insulation may cover existing knob-and-tube wiring only after a licensed contractor certifies its condition, with Class I insulation and 60 degree C overcurrent protection (breakers or Type S fuses) |
| -408 | Service equipment and panelboards may not be in clothes closets, toilet rooms, or shower rooms |
| -410 | Luminaires in an enclosed shower or within 5 ft of a tub waterline must be enclosed (unless listed for the use); those with exposed grounded metal need GFCI |
| -422 | Water heaters over 3,500 W at 208 or 240 V need branch-circuit conductors of at least #10 AWG copper |
| -450 | Outdoor oil-filled transformers: no doors, windows, stairways, or openings within 8 ft; at least 2 ft from nonhabitable structures and outside the drip line of the eaves |
Test Your Knowledge
A service disconnect will be installed inside a warehouse. The service conductors have no customer-owned supply-side overcurrent protection. Under WAC 296-46B-230, how far may the service raceway extend inside the building?
A
B
C
D
Test Your Knowledge
Which wiring method does WAC 296-46B-230(7) permit for service conductors inside a building?
A
B
C
D
Test Your Knowledge
Under WAC 296-46B-422, what is the minimum branch-circuit conductor for a 4,500-watt, 240-volt storage water heater?
A
B
C
D