Short answer: Article 312 covers the enclosure: cabinets, cutout boxes and meter socket enclosures (NEC 312.1). Where the wiring space of a cabinet is used for conductors feeding through, splices or taps, conductors may fill no more than 40 percent of its cross section, and conductors with splices and taps no more than 75 percent; the section has other conditions too, so read all of it (NEC 312.11(A)). Article 404 now covers general-use and motor-circuit switches, not device-type wall switches (NEC 404.1(A)). Its installation rules most worth knowing: weatherproof enclosures in damp or wet locations (NEC 404.6(A)), single-throw knife switches mounted so gravity will not close them (NEC 404.8(A)), and operating handles no higher than 2.0 m (6 ft 7 in) (NEC 404.10(A)(2)).
PSI lists cabinets and panels in the Wiring Methods and Materials subject area of the Texas Journeyman exam (10 scored NEC Knowledge questions), and switches in the Electrical Equipment and Devices subject area (10 scored NEC Knowledge questions). PSI does not say how many cover Articles 312 or 404. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Which article is the question about?
| The question is about | Go to |
|---|---|
| The box or enclosure itself: wiring space, wet locations, bending space | Article 312 |
| The panelboard inside: overcurrent protection, circuit directory, spaces | Article 408, covered in NEC 408 panelboards |
| A safety switch, motor-circuit switch or knife switch | Article 404 |
| A snap switch, dimmer or wall switch on a lighting circuit | Article 406 in the 2026 NEC, covered in NEC 406 and 410 |
In the 2026 NEC, device-type switches moved from Article 404 to Article 406, now titled Wiring Devices. A question that asks about a wall switch box or a dimmer is not a 404 question anymore. Time switches also moved, to 406.34.
Article 312: three rules for the enclosure
- Wiring space. When the cabinet carries conductors feeding through or holds splices and taps, total conductor area at any cross section is limited to 40 percent, and conductors with splices and taps to 75 percent. Both limits apply, and the same section adds other conditions, so a question can test a condition rather than a percentage (NEC 312.11(A)).
- Wet and damp locations. Where raceways or cables enter above the level of uninsulated live parts in a damp or wet location, the fittings must be listed for wet locations (NEC 312.4(B)). In the 2023 NEC this rule was in 312.2.
- Bending space. Conductors need room to bend at the terminals. Section 312.6 sets that space; check the tables in your 2026 NEC.
Worked example: wiring space in a cabinet
A cabinet’s wiring space has a cross section of 3 × 8 inches.
- Cross-section area. 3 × 8 = 24 square inches.
- Feed-through conductors, 40 percent. 24 × 0.40 = 9.6 square inches.
- Conductors plus splices and taps, 75 percent. 24 × 0.75 = 18 square inches.
- Use it. If each conductor takes 0.80 square inches, 9.6 ÷ 0.80 = 12 conductors at the 40 percent limit. This is the area check only; the other conditions in the section still apply.
Article 404: installation rules for switches
- Damp or wet locations. A surface-mounted switch or circuit breaker goes in a weatherproof enclosure that complies with 312.4 (NEC 404.6(A)). A flush-mounted one gets a weatherproof cover (NEC 404.6(B)).
- Barriers. Where adjustable switch barriers are used, energized parts within 6 inches are barriered; check the exception in your NEC (NEC 404.7).
- Knife switches. Single-throw knife switches are placed so gravity will not tend to close them (NEC 404.8(A)). A blade that drops onto the contacts when a hinge pin wears is the hazard.
- Height. The center of the operating handle grip, in its highest position, is not more than 2.0 m (6 ft 7 in) above the floor or working platform. Busway switches have an exception (NEC 404.10(A)(2)).
- Marking. General-use and motor-circuit switches are marked with their current, voltage and, where applicable, horsepower ratings (NEC 404.20(A)).
Check yourself
- A cabinet’s wiring space is 4 × 6 inches. What is the 40 percent limit? 24 × 0.40 = 9.6 square inches.
- Is a single-pole wall switch on a lighting circuit a 404 question in the 2026 NEC? No. Device-type switches are in Article 406.
- A safety switch handle sits 7 feet above the floor at its highest position. Does it comply? No. 7 feet is more than 6 ft 7 in.
Disclosure: If you buy through the Amazon link below, Tsai Electro may earn a commission at no extra cost to you. As an Amazon Associate I earn from qualifying purchases.
Find 312 and 404 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). Write “device switches: see 406” at the top of Article 404, so the 2026 move does not cost you time. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
How much of a cabinet’s wiring space can conductors fill?
40 percent of the cross section for conductors, and 75 percent for conductors with splices and taps at any cross section of the wiring space. These percentages do not replace the section’s other conditions.
What does Article 404 cover in the 2026 NEC?
General-use switches and motor-circuit switches, including circuit breakers used as switches. Device-type switches such as snap switches and dimmers moved to Article 406.
How high can a switch handle be mounted?
The center of the operating handle grip, in its highest position, may be no more than 2.0 m (6 ft 7 in) above the floor or working platform, with an exception for busway switches.
Which way must a knife switch be mounted?
A single-throw knife switch is placed so gravity will not tend to close it.
Are cabinets and switches on the Texas Journeyman exam?
PSI lists cabinets and panels in Wiring Methods and Materials, and switches in Electrical Equipment and Devices. Each area has 10 scored NEC Knowledge questions.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, Articles 312, 404 and 406
