Electrician Red Seal · Question
An electrician is troubleshooting a voltage sag issue in a commercial building. Measurements at the main service entrance show the line-to-neutral voltage on one phase briefly dropping from 120 V to 95 V during peak load conditions. What is the approximate percentage voltage sag experienced?
Voltage sag percentage is calculated as ((Nominal Voltage - Sag Voltage) / Nominal Voltage) * 100%. In this case, ((120 V - 95 V) / 120 V) * 100% = (25 V / 120
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Question: An electrician is troubleshooting a voltage sag issue in a commercial building. Measurements at the main service entrance show the line-to-neutral voltage on one phase briefly dropping from 120 V to 95 V during peak load conditions. What is the approximate percentage voltage sag experienced?
Answer options: ✅ 20.8%
- 26.3%
- 15.8%
- 20.0%
Correct answer: 20.8%
Explanation: Voltage sag percentage is calculated as ((Nominal Voltage - Sag Voltage) / Nominal Voltage) * 100%. In this case, ((120 V - 95 V) / 120 V) * 100% = (25 V / 120 V) * 100% = 0.2083 * 100% = 20.83%.
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