AWS Certified Welding Inspector — FundamentalsSafetyEasy
A welder is setting up for a gas metal arc welding (GMAW) operation. The welding machine is powered by 480V three-phase electricity. Before connecting the power, the welder should ensure the machine's power cord is equipped with which of the following?
- AA standard household 120V plug.
- BA non-polarized two-prong plug.
- CA two-prong ungrounded plug.
- DA three-prong grounded plug.
Show answer & explanationAnswer & explanation
Correct answer: D. A three-prong grounded plug.
Proper grounding is essential for electrical safety, especially with high-voltage equipment like a 480V welding machine. A three-prong grounded plug ensures a safe path for fault current, protecting the operator from shock.
Why the other options are wrong
- A. A standard household 120V plug is incompatible with a 480V three-phase machine and would not provide adequate grounding.
- B. A non-polarized two-prong plug is ungrounded and unsafe for this application.
- C. An ungrounded plug offers no protection against electrical shock in case of a fault and is unsafe for high-voltage equipment.
Electrical Grounding
The process of connecting electrical equipment to the earth, providing a low-resistance path for fault currents to safely dissipate, preventing electric shock.
- Protects against electric shock.
- Requires a dedicated ground wire.
- Essential for high-voltage equipment.
Memory trick: Three prongs for safety, one for the ground, keeping all the danger safely unbound.