Electrician Red Seal · Question
A residential customer complains of dimming lights and warm panel breakers, despite not adding new large loads. An electrician checks the service and finds the total active power is 15 kW and the apparent power is 20 kVA. What is the power factor at the service entrance?
Power factor (PF) is the ratio of active power (P) to apparent power (S). So, PF = P / S. Given P = 15 kW and S = 20 kVA, PF = 15 kW / 20 kVA = 0.75. The sympto
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Question: A residential customer complains of dimming lights and warm panel breakers, despite not adding new large loads. An electrician checks the service and finds the total active power is 15 kW and the apparent power is 20 kVA. What is the power factor at the service entrance?
Answer options:
- 0.65 lagging ✅ 0.75 lagging
- 0.85 lagging
- 0.95 lagging
Correct answer: 0.75 lagging
Explanation: Power factor (PF) is the ratio of active power (P) to apparent power (S). So, PF = P / S. Given P = 15 kW and S = 20 kVA, PF = 15 kW / 20 kVA = 0.75. The symptoms of dimming lights and warm breakers without new loads suggest a low power factor, leading to higher reactive current and thus higher total current for the same active power.
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