What is the danger of using two ground wires on a piece of diagnostic equipment?

What is the danger of using two ground wires on a piece of diagnostic equipment?

• A. Ground loop
• B. Electric shock
• C. Galvanized skin response
• D. Common mode rejection

Answer: (A)

Ground loop is the danger here. When two separate ground wires create a closed loop, any small difference in earth potential between those grounds causes a circulating current to flow around the loop. That current can travel through the patient and through the equipment via the measurement leads, creating a shock risk and, at the same time, introducing noise and artifacts into the diagnostic readings. Using a single grounding point or proper isolation minimizes this loop and avoids the hazardous circulating current. The other options don’t describe this specific mechanism: while shock is a possible consequence, the core issue is the loop current; galvanic skin response is unrelated, and common mode rejection concerns signal amplification, not a grounding hazard.

Ground loop is the danger here. When two separate ground wires create a closed loop, any small difference in earth potential between those grounds causes a circulating current to flow around the loop. That current can travel through the patient and through the equipment via the measurement leads, creating a shock risk and, at the same time, introducing noise and artifacts into the diagnostic readings. Using a single grounding point or proper isolation minimizes this loop and avoids the hazardous circulating current. The other options don’t describe this specific mechanism: while shock is a possible consequence, the core issue is the loop current; galvanic skin response is unrelated, and common mode rejection concerns signal amplification, not a grounding hazard.