Basic Home Electrical Installation Calculations

If you ever intend to install or work on any of the electrical systems in your home then you need to understand how to use electrical installation calculations. These calculations will help to ensure that the equipment you are installing will be able to satisfy your homes requirements.

One of the most important calculations to master is the electrical load calculation. This will work out how much electricity your home will require at any one time. The idea behind this is to ensure that the wiring and electrical panel in your home are able to provide that much power safely without being a potential fire hazard. Working this out can also help you to reduce your homes waste of electricity which should reduce your electricity bills.

Step 1 - Preparation

You must first go around your home and take a look at the labels on the back of each electrical appliance. These labels should say how much power they use, there are two ways of writing this. They might rate their power usage in Watts or Amps. It's important to convert all of them to Watts as this will make calculating your homes electrical load much easier.

To work out the number of Watts for an appliance with an Amp rating you simply need to multiply Amps by the Voltage. In the vast majority of cases this will be 120 V. This means that a 3amp appliance plugged into a 120V outlet will have a rating of 360 Watts. By working this out you will be able to work out how many kWh or Kilowatt Hours your home is using.

Step 2 - Working out Times

Now roughly try to work out when you will be using the various electrical appliances and how long you will be using all of them. Make sure that you allow for your refrigerator, water heater and heating systems because these will normally control themselves and you will not have control over them. One way of doing this is to create a log of the times each day you use the various appliances for. Keep this log for a few days and it should then be possible to get an accurate estimation of your energy requirements.

The rating labels on the back of your appliances are the maximum power use of that appliance. Refrigerators for example will not use much power unless the compressor is running.

Step 3 - Calculating Energy Usage

Now work out the number of watts that you will use per appliance per day. If you aren't sure about certain appliances such as cooling and heating units then you can search the Internet to get estimated figures.

Step 4 - Calculating kWh

Now calculate the kWh for each appliance. To work out the kWh you simply need to multiply the number of watts by the hours you use the appliance for, and then divide it by 1000. A 100 watt light bulb which was used for 10 hours will only use one kWh (100W x 10) / 1000 = 1000/1000 = 1

Step 5 - Totaling Your Requirements

Now add up all of the kWh required to power all of the appliances in your home in an average day, this will help you to understand your homes daily electrical requirements.

Step 6 - Accuracy

If you are interested in perfecting your results and making them more accurate then you can use a watt meter which is plugged into the receptacle. Watt meters will tell you exactly how much electricity your appliances are using.