On a main switchboard, if all three ground...

On a main switchboard, if all three ground...

Question 1 of 270705eccefa4bacbc34ba4d483d5

On a main switchboard, if all three ground detection lamps burn with equal intensity before and after the test button is depressed, which of the listed conditions is indicated?

Question 1 of 27070

Q

On a main switchboard, if all three ground detection lamps burn with equal intensity before and after the test button is depressed, which of the listed conditions is indicated?

🔍 Key Concepts

• Ground detection lamp circuits on a three‑phase system and what “equal intensity” means • What should normally happen to the lamps when the test button is pressed if there is no ground • How a single line‑to‑ground fault vs. multiple grounds would change lamp brightness

💭 Think About

• Think about what the lamps are comparing: phase voltage to ground. If everything is normal, how will each lamp behave before and during the test? • When the test button is pushed, does it intentionally simulate a ground or remove one? How should that change at least one lamp’s brightness if the system is working correctly? • If a real ground existed on one phase, which lamp (for that phase or the other phases) would you expect to change in brightness compared to the others?

✅ Before You Answer

• Be clear on what the test switch actually does in a standard ground detection circuit (does it create a temporary ground or open the circuit?). • Ask: if all three phases were grounded, would the voltages to ground be equal or not, and would the detector even work normally? • Verify which option corresponds to a condition where the indicator circuit is healthy and no asymmetry to ground is detected even during the test.