Using a generator as an emergency backup power supply is an easy way to power some of your appliances in the event of a power cut.
But just what size generator do you need to run your electrical appliances. Unfortunately it’s not as simple as my 800w microwave requires 800w so my 950w inverter generator will more than suffice.
First we need to understand how electrical appliances draw power, we can split them into 3 basic categories.
- Resistive – incandescent light bulbs, these draw constant power. A 100w light bulb only ever needs 100w to turn and run. Doing the sums for resistive load appliances is pretty straight forward.
- Capacitive – These are basically appliances that contain a lot of capacitors, such as Televisions, Hi-Fi Amplifiers etc. The capacitors do the job of storing power like a battery, as time passes,the power drains out of them and the appliances may require a larger surge of starting current then running current to turn the appliance on. The longer the duration between off and on cycles the larger the current surge required. The shorter the duration the less starting current is required.
- Inductive – Inductive appliances are those which use motors, transformers, ballasts and solenoids. When they are turned on they require a very much larger current surge to start as opposed to just run. Some examples of inductive appliances are microwaves, fridges, freezers, hoovers, fluorescent lights etc..
Inductive appliances such as fridges and freezers are also probably the sort of appliances that we most want to run during a power cut. As these are the most power hungry examples of appliances to start and run lets take a look at some running watts and theoretical required starting watts.
Microwave Oven 625w – starting watts 800w
Freezer 700w – starting watts 2200w
Washing Machine 1150w – starting watts 2300w
Air Con 20,000BTU 2500w – starting watts 3300w
