Hair dryer heater coils (traditional dryers) use Ni-Cr alloy wire for resistive heating, wound around ceramic/mica insulators to maximize heat transfer and safety. Ni-Cr is chosen for high resistance (efficient heat), thermal stability (1,200°F), and oxidation resistance. Coil specs (gauge/length) define performance: 18–20 AWG (thick) for 2,000–2,400W salon dryers, 22–24 AWG (thin) for 1,200–1,600W travel models. Safety systems include bimetallic thermostats (cuts power at 180–200°F) and thermal cutoffs (250°F fail-safes). Issues: breakage (dropping/duty cycles), oxidation (uneven heat), shorts (moisture). Signs: cold air, sparking, burning odors. Replacements require matching gauge/length/resistance (10–50 ohms). Compliance with UL (North America), CE (Europe), CCC (Asia) ensures global safety. Maintenance (cleaning vents) extends life to 2–3 years (home) or 1–2 years (salon), meeting diverse user needs.