ELECTRICITY BILL

Power Ratings of Home Appliances

The power ratings of various home appliances in watts are listed below.
Appliance Name Power (W)
Air Conditioner (room) 1350
Ceiling Fan 75
CFL 9-55
Clock 4
Coffee Maker 850
Computer (PC) 360
Heater, portable 1500
Incandescent Light Bulbs 4-28
Inkjet Printers 50-60
Iron (hand) 1100
Laptop 25-40
LEDs 4-28
Lighting-Kitchen 250
Lighting-Bedrooms 450
Lighting-Outdoor 150
Lighting-Living Room 500
Lighting-Office 150
Lighting-Other 400
Refrigerator 265-500
Table Fan 40
Television 250
Vacuum cleaner 700
Washing machine 600
Water heater (electric) 3200

Electrical Energy
The total work done in an electric circuit is called electrical energy i.e.,
Electrical Energy = Electrical Power X Time
𝑉2
= 𝑉𝐼 𝑡 = 𝐼 2 𝑟 𝑡 = 𝑡
𝑟
The unit of electrical energy consumed is watt-second or joule. One watt-second (or joule)
energy is transferred between two points if a potential difference of 1 volt exists between them and
1 ampere current passes between them for 1 second.
Electrical energy in watt-sec (or joules)
= voltage in volts X current in amperes X time in seconds
Joule or watt-sec is a very small unit of electrical energy for practical purposes. In practice,
for the measurement of electrical energy, bigger units i.e., watt-hour or kilowatt-hour are used.
1 watt-hour = 1 watt X 1 hour
= 1 watt X 3600 sec = 3600 watt-sec
1 kilowatt-hour (kWh) = 1kW X 1hour = 1000 watt X 3600 sec
 (As 1 hour = 60 minutes = 60 X 60 seconds)
= 36 X 105 watt-sec

The electrical energy can also be expressed in Joules instead of kWh.

Maximum demand is the greatest demand of load on the power station during a given
period.
Load factor is the ratio of average load to the maximum demand during a given period
given by
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑
𝐿𝑜𝑎𝑑 𝑓𝑎𝑐𝑡𝑜𝑟 =
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝑋 𝐿𝑜𝑎𝑑 𝑓𝑎𝑐𝑡𝑜𝑟
𝑈𝑛𝑖𝑡𝑠 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑝𝑒𝑟 𝑎𝑛𝑛𝑢𝑚 = 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 (𝑖𝑛 𝑘𝑊) 𝑋 𝐻𝑜𝑢𝑟𝑠 𝑖𝑛 𝑎 𝑦𝑒𝑎𝑟
= 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 (𝑖𝑛 𝑘𝑊) 𝑋 𝐿𝑜𝑎𝑑 𝐹𝑎𝑐𝑡𝑜𝑟 𝑋 8760
If the plant is in operation for ‘T’ hours, then
𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 𝑋 𝑇
𝐿𝑜𝑎𝑑 𝑓𝑎𝑐𝑡𝑜𝑟 =
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝑋 𝑇

𝑈𝑛𝑖𝑡𝑠 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑖𝑛 𝑇 ℎ𝑜𝑢𝑟𝑠

=
𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑚𝑎𝑛𝑑 𝑋 𝑇 ℎ𝑜𝑢𝑟𝑠
The load factor may be daily load factor, monthly load factors or annual load factor if the
time period considered is a day or month or year. Load factor is always less than 1 because average
load is smaller than the maximum demand.
Average load or average demand is the average of loads occurring on the power station
in a given period (day or month or year).
𝑁𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 (𝑘𝑊ℎ) 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑖𝑛 𝑎 𝑑𝑎𝑦
𝐷𝑎𝑖𝑙𝑦 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 =
24 ℎ𝑜𝑢𝑟𝑠
𝑁𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 (𝑘𝑊ℎ) 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑖𝑛 𝑎 𝑚𝑜𝑛𝑡ℎ
𝑀𝑜𝑛𝑡ℎ𝑙𝑦 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 =
𝑁𝑜. 𝑜𝑓 ℎ𝑜𝑢𝑟𝑠 𝑖𝑛 𝑎 𝑚𝑜𝑛𝑡ℎ
𝑁𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 (𝑘𝑊ℎ) 𝑔𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 𝑖𝑛 𝑎 𝑦𝑒𝑎𝑟
𝑌𝑒𝑎𝑟𝑙𝑦 𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝐿𝑜𝑎𝑑 =
8760 ℎ𝑜𝑢𝑟𝑠

Cost of Electrical Energy

The total cost of electrical energy divided into
(i) Fixed Cost: It is the cost which is independent of maximum demand and units
generated.
(ii) Semi-fixed Cost: It is the cost which depends upon maximum demand but is
independent of units generated.
(iii) Running or Operating Cost: It is the cost which depends only upon the number of
units generated.

Tariff
The rate at which electrical energy is supplied to a consumer is known as tariff.
Although tariff should include the total cost of producing and supplying electrical energy
plus the profit, yet it cannot be the same for all types of consumers. It is because the cost of
producing electrical energy depends to a considerable extent upon the magnitude of electrical
energy consumed by the user and their load conditions. Therefore, in all, due consideration has to
be given to different types of consumers (e.g., industrial, domestic and commercial) while fixing
the tariff. This makes the problem of suitable rate making highly complicated.

Objectives of Tariff
Like other commodities, electrical energy is also sold at such a rate so that it not only
returns the cost but also earns reasonable profit. Therefore, a tariff should include
(i) Recovery of cost of producing electrical energy at the power station.
(ii) Recovery of cost on the capital investment in transmission and distribution systems.
(iii) Recovery of cost of operation and maintenance of supply of electrical energy e.g.,
metering equipment, billing etc.
(iv) A suitable profit on the capital investment.

Types of Tariff
There are several types of tariff. However, the commonly used types of tariff are
(i) Simple Tariff or Uniform Rate Tariff
(ii) Flat Rate Tariff
(iii) Block Rate Tariff
(iv) Two-part Tariff
(v) Maximum Demand Tariff
(vi) Power Factor Tariff
(vii) Three-part Tariff

Essentials to know about Tariff

• The cost of producing electrical energy is not same for all consumers but increases with
the increasing departure of consumer’s load conditions from the ideal (i.e., constant load).
• The total cost of electrical energy consists of fixed charges and running charges. The
greater the number of units consumed, the lesser the fixed charges per unit. Therefore, a
consumer who consumes more units must pay less fixed charges per unit.
• The flat rate for power load is always less than lighting load. It is because power load is
much more than the lighting load and therefore, improves the load factor of the system to
a great extent.
• Generally, fixed charges are merged into the running charges for the first and second blocks
of energy so that price per unit for these blocks is high.
• The maximum demand of consumers is generally assessed on the basis of rateable value of
the premises or on the number of rooms or on the connected load.

Two-part Tariff
When the rate of electrical energy is charged on the basis of maximum demand of the
consumer and the units consumed, it is called two-part tariff.
In two-part tariff, the total charge to be made from the consumer is split into two
components: fixed charges and running charges. The fixed charges depend upon the maximum
demand of the consumer while the running charges depend upon the number of units consumed
by the consumer. Thus, the consumer is charged at a certain amount per kW of maximum demand
plus a certain amount per kWh of energy consumed i.e.,
 Total charges = Rs (b X kW + c X kWh)
b = a constant which when multiplied by maximum kW demand on the
where, station gives the annual cost of the first part (or charge per kWh of
maximum demand)
c = a constant which when multiplied by kWh generated gives the
annual running cost (or charge per kWh of energy consumed)
This type of tariff is mostly applicable to industrial consumers who have appreciable
maximum demand.

Advantages of Two-part Tariff

1. It is easily understood by the consumers.
2. It recovers the fixed charges which depend upon the maximum demand of the consumer
but are independent of the units consumed.

Disadvantages of Two-part Tariff

1. The consumer has to pay the fixed charges irrespective of the fact whether the consumer
has consumed or not consumed the electrical energy.
2. There is always error in assessing the maximum demand of the consumer.

Calculation of electricity bill for domestic consumers

To calculate your electric bill, you’ll need to figure the energy usage of each of the
appliances and electronic devices in your home. In an ideal world, estimating your electricity usage
would be as easy as looking at an itemized grocery receipt. You’d be able to see exactly what you
spent to run the dishwasher, do the laundry, watch TV and use a month’s worth of hot water. That
technology is getting closer every day, but if you want to get an appliance-by-appliance breakdown
right now, you’ll need to do a little math or spend a little money.
To get a truly accurate accounting of the energy consumption of your home, you’ll need to
use some modern technology. But you may be able to calculate some decent estimates using some
simple, old-fashioned arithmetic.
To estimate electricity usage of a particular appliance or electronic device, you’ll need
three figures: the wattage of the appliance, the average number of hours you use it per day, and the
price you pay per kilowatt-hour (kWh) of electricity.
Your kWh rate is printed right on your electric bill, and the average daily use is easy enough
to figure. To determine the wattage of an appliance, look for a label or metal plate, which is usually
in an inconspicuous place like the back or bottom of the appliance or device. If the wattage is
listed, it will have a “W” at the end. If you can’t find a label, check the appliance’s original
documentation or try searching online for its technical specs.
Once you have your data, calculate the cost of use with this formula:
• Multiply the device’s wattage by the number of hours the appliance is used per day
• Divide by 1000
• Multiply by your kWh rate
So, if you have a 150W television that you watch five hours per day, it consumes 750watt-
hours per day (150 x 5 = 750). Divide 750 by 1000 to convert 750 watt-hours into 0.75kWh
(750/1000 = 0.75). If your electricity rate is 20 paise per kWh, that means it costs 0.15 paise per
day to use your television (0.75 x 0.20 = 0.15). That should account for about Rs. 4.50 of your
monthly electric bill (0.15 x 30 = 4.50).
 It will take a lot of number crunching to do this with all the appliances, electronics and lights
in your home, so if you’re looking for an easier way, turn to technology.
For example, to calculate electricity bill for domestic consumers, select LT-1A and purpose as
domestic in the link (https://www.kseb.in/bill_calculator_v12/)

Billing Cycle (for 100 Billing Cycle (for 100

Bill Details
consumed units) consumed units)
Phase Single Phase Three Phase
Billing Cycle 1 month 2 months 1 month 2 months
Energy Charge 342.67 315.34 342.05 315.10
Duty 34.25 31.50 34.25 31.50
Fixed Charge 45.00 70.00 90.00 180.00
Meter Rent 6.00 12.00 15.00 30.00
Meter Rent Central GST 0.54 1.08 1.35 2.70
EC Subsidy -44.00 -38.00 -44.00 Not Applicable
Meter Rent State GST 0.54 1.08 1.35 1.08
FC Subsidy -20.00 -40.00 Not Applicable Not Applicable
Total Amount 365.00 353.00 440.00 562.00