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OSHA electrical (Subpart K) for the CHST

Toe Board editorial teamSources checked 3 min read

Temporary power is everywhere on a construction site, and it is a leading cause of fatal injuries. The CHST blueprint puts common electrical hazards and controls in Domain 1. Subpart K (29 CFR 1926.400 to 1926.449) is the construction electrical standard. This guide maps the parts the exam leans on, in our own words.

Check anything you rely on against your own licensed code book and the edition your AHJ enforces.

Where Subpart K sits in the blueprint

Electrical hazards are item 2 in the Domain 1 knowledge list, and Domain 1 is 36.6% of the CHST. Most questions test a control choice: de-energize, ground-fault protection, guarding or distance.

The sections to know

  • 1926.403 covers general requirements: listed or labeled equipment, installation and use per instructions, and working space.
  • 1926.404 covers wiring design and protection. For temporary power, 1926.404(b)(1) is the key paragraph: ground-fault circuit interrupters on the 120-volt, single-phase, 15 and 20 ampere receptacles that are not part of the permanent wiring, or an assured equipment grounding conductor program as the alternative.
  • 1926.405 covers wiring methods, components and equipment: temporary wiring, cords and cables, lighting and flexible cord use.
  • 1926.416 covers general safety requirements: no one works near an energized circuit that they could touch, unless it is de-energized or guarded, and it covers cord and cable condition.
  • 1926.417 covers lockout and tagging of circuits: equipment is de-energized, locked or tagged, and tested before work.
  • 1926.449 holds the definitions.

Overhead power lines near cranes and booms are also covered in Subpart CC and near scaffolds in Subpart L.

Try one question

Question 1 of the free 10-question check on CHST. No signup.

Question 1 of 10 · free checkUntimed

Emergency Preparedness, Incident Investigation, and Response

On a building under construction, what is the longest allowed travel distance from any point of the protected area to the nearest fire extinguisher?

Choose an answer to begin

Controls in order

  1. Eliminate the hazard: de-energize and lock out.
  2. Engineering controls: GFCIs, insulation, guarding, grounded equipment.
  3. Administrative controls: the assured grounding program, inspections and test schedules, permits.
  4. PPE: insulating gloves and tools, as the last layer.

Common mix-ups

  • GFCI or assured grounding? Both are allowed on temporary power: a GFCI for each receptacle, or a written assured grounding program with its testing and records. Read which one the question's site uses.
  • Tagout is not lockout. A tag warns and a lock prevents. Lockout is the stronger control.
  • Guarded is not de-energized. The exam may offer a barrier where the correct action is to de-energize.
  • Distance changes with voltage. The clearance figures are in tables and grow with voltage. Use your own copy.

How to practice

For each of the four control levels, list one temporary power example. Then work questions that describe a damaged cord, a wet area or a line near a boom, and decide the first action.

Related guides: fall protection and cranes and derricks.

Practice it

Take the free 10-question check. It covers the four CHST domains, needs no signup and explains every answer, so you see whether this subpart is a weak spot. The CHST study guide shows where it fits in a six-week plan.

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Sources

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Facts checked 24 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.

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Study guideOSHA fall protection (Subpart M) for the CHSTStudy guideOSHA excavations (Subpart P) for the CHSTStudy guideOSHA scaffolds (Subpart L) for the CHSTStudy guideOSHA cranes and derricks (Subpart CC) for the CHSTStudy guideOSHA ladders and stairways (Subpart X) for the CHSTStudy guideOSHA confined spaces (Subpart AA) for the CHSTStudy guideOSHA health hazards: silica, lead and noise for the CHSTStudy guideOSHA recordkeeping (Part 1904) for the CHST