Is it true that electronic equipment consume a lot of power when they are on their standby mode and presumably turned off? We took a digital power meter and measured the most common electronic equipment found at home to check this out. We came to out with very interesting results. Read on.

The “correct” way to turn off an electric or an electronic equipment would be by really cutting its power source, by either removing the equipment from the AC outlet or by using a mechanical switch (the same kind of switch that is used to turn on and off a light at your home). In the past, that was the kind of switch all equipment had.

 The problem of using mechanical switches is that you can’t turn on your equipment with a remote control or can’t have some functions enabled while your equipment is turned off – for example, the clock found on VCR’s and microwave ovens.

Most of the electronic equipment today use an electronic switch that is controlled by a circuit that is always turned on. This circuit keeps monitoring the remote control sensor of the equipment, allowing you to turn on your equipment remotely. When the equipment is turned off it keeps feeding this circuit, and that is why we say that the equipment is under standby mode, as it is still pulling current from the AC outlet, what wouldn’t happen if it was really turned off.

The on/off switch present on this kind of equipment isn’t a mechanical switch but simply a push-button that commands the standby circuit to turn on the equipment. Some equipment have a “real” on/off switch, a “master” mechanical switch that really turns off the equipment.

For example, when you turn off your PC the power supply isn’t entirely shut down. A circuit called standby power is always turned on, supplying voltage to one of its outputs called standby power (or +5VSB) and waiting for you to push the power button located on your computer case. Some power supplies have a master switch on their rear side. This switch is a mechanical switch that will really turn off the power supply. If you turn it off you can push the power button located on the case frontal panel as many times as you want and you computer won’t turn on, as the power supply will be really turned off.

So if electronic equipment have a circuit being fed all the time even when they are turned off, this means that almost all electronic equipment that we have at home is consuming electricity – costing us money –even when they are turned off. Manufacturers usually claim that the standby power consumption is negligible. Is that true? This is exactly what we wanted to see with our experiment.

We bought a digital power meter and started to measure the consumption of all electronic equipment we had at home when they were “turned off”. Not only that. We seized the opportunity to also measure the power consumption of equipment that we always forget turned on – computer speakers, printers, broadband modems, broadband routers, cell chargers and generic battery chargers, for example.

We divided the results into four groups: zero consumption, negligible (consumption below 0.5 W), significant (between 0.5 W and 10 W) and huge (above 10W). The results were quite surprising. Read on.