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