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DE Electrician: Electrical Installation, Safety, and Inspection

DE Electrician · Work through your exam, one topic at a time.

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Electrical Installation, Safety, and Inspection

This domain tests field execution: installing listed equipment correctly, maintaining safe work practices, and surviving an inspection. It blends NEC installation rules with OSHA and NFPA 70E safety and the AHJ inspection process.

Before and during installation

  • Obtain permits and approved plans before starting; concealed work must be inspected before covering.
  • Verify equipment is listed and labeled for the use; follow instructions under 110.3(B).
  • Support and secure cables and raceways as the wiring method requires. NM cable generally must be secured within 12 inches of boxes and every 4.5 feet, and protected where subject to damage.
  • Keep conduit fill, bend radius, and box fill within Chapter 9 and Article 314 limits.
  • Maintain 110.26 working space: at least 3 feet deep for 600 V or less, 30 inches wide, 6.5 feet high, with dedicated equipment space above panelboards.
  • Torque terminations to the manufacturer's values; use listed connectors and bushings.

Safety and inspection

  • De-energize and verify absence of voltage before working; use lockout/tagout, test the tester on a known source, and treat all conductors as energized until tested.
  • Follow NFPA 70E for arc-flash risk assessment and PPE; an energized work permit is required when energized work is justified.
  • Temporary power must use GFCI protection and listed cords; do not use damaged cords or ungrounded adapters.
  • Final inspection items include grounding and bonding continuity, polarity, GFCI/AFCI operation, panel labeling, cover plates, and clear working space.

Worked example

An inspector finds a 200-ampere panelboard in a basement with a water pipe running 30 inches in front of the panel face. The working-space depth for 120/240-volt equipment is 3 feet, measured from the live parts or enclosure front as applicable, so 30 inches is insufficient. The pipe is also a foreign object in the dedicated space. The contractor must relocate the pipe or the panel; adding a sign or warning label does not cure the violation.

Traps

  • Trusting a switch position instead of testing for voltage.
  • Using GFCI as a substitute for lockout/tagout or PPE.
  • Covering work before rough-in inspection.
  • Missing cable support distances or conduit fill limits.
  • Ignoring arc-flash labels and shock boundaries.
  • Assuming a local AHJ accepts the NEC without amendments.