A typical American family uses 1000 kWh of electricity a month.
A) What is the average current in the 120 V power line to the house?
B) On average, what is the resistance of a household?
Answer:
P=E/t
Let’s make an assumption that the power factor is 1.00
let’s take a month of 30 days or 720 hours.
Then 1000000 watt divided by 720 = wattage per hour=1388.9
P=1389 W
I=P/V
Wattage/hr divided by line voltage = av. current=11.57 amperes
I=11.6 A
Again assuming that the load is ‘resistive’ and not inductive
Resistance is voltage divided by current 120/11.57=10.37 ohms
The assumptions made is to remove the impact of inductive loads, which reduces the power factor below 1.0, and increases the apparent current draw.
Task #2:
A typical American family uses 800 kWh of electricity a month. What is the average current in the 120 V power line to the house?
Answer:
Let’s take a month of 30 days or 720 hours.
800000Wh/720h = 1111 W
