Red Seal Electrician Practice
Wiring and componentsQuestion 78 of 1506

A 12 V DC relay coil is controlling a 480 V AC circuit through its contact. What does this show about relays?

  1. The relay coil and contacts must be at the same voltage and type
  2. A relay can only switch DC loads and cannot switch AC loads
  3. A small low-voltage signal can switch a high-voltage circuit and isolate it
  4. The contact must be rated lower than the coil that it is controlled by
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Correct answer: A small low-voltage signal can switch a high-voltage circuit and isolate it

The coil and contact circuits are insulated from each other.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 5.1: Relay Construction

Practice wiring and components

Questions last reviewed: 18 October 2026