How Much Power Do Electronic Equipment Consume When in Standby Mode?
By Gabriel Torres on January 22, 2008


Introduction

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.

Zero Consumption

We could see some equipment at home not consuming absolute nothing from the power grid when they are in standby mode. Of course they consume something, but the current is so low that our power meter read it as 0.00 W.

This is just a sample and of course you may have equipment from the categories below that consume something when in standby mode, if they are from a different brand or are a different model. That is why we are specifying the brand and model.

The equipment that were consuming absolute nothing when in standby mode were the following:

We were really surprised by our TV. Since it consumes a lot when turned on, we thought that it would be consuming something when in standby mode. Not at all. The result from the audio receiver was expected, as receivers from Sony and other brands use a relay (which is an electromechanical switch) to shut down the unit (you can clearly hear a loud click after pressing the power switch coming from the relay). The result from the DVD player was also expected, as even when they are playing discs they don’t consume a lot of power (below 10 W).

We added the cell charger and the battery charger because many people have the habit of leaving them attached to the wall all the time. From what we could see, you can keep doing this. Of course when you install the cell phone or the batteries they will start consuming some power.

And for some people the surge protector consuming nothing would be obvious, but not for us, because surge protectors have some LEDs that are always turned on and we were afraid that such LEDs could be consuming something. It appears that it isn’t the case.

Negligible Consumption

In this category we are listing the equipment that are consuming something from the power grid, but below 0.5 W, meaning that they have no visible impact on your electricity bill. Of course if you are paranoid on savings you can remove all of them from the wall – but if you are really paranoid you are probably already removing every piece of electronic device from the wall anyway.

Like we said before this is just a sample and of course you may have equipment from the categories below that consume different power levels when in standby mode, if they are from a different brand or are a different model. That is why we are specifying the brand and model.

The equipment that had negligible consumption when in standby mode were the following:

When thought that with the computer turned off and with the blue LED from our monitor blinking the monitor would be consuming an expressive value, but that was not the case. But if you press the power button to turn off the blinking LED the power is cut in a half, going from 0.2 W to 0.1 W.

The consumption of the microwave oven clock is negligible, so you can leave it attached to the wall.

The highest consumption in this category was from the battery charger. As mentioned before we added the battery charger with no batteries installed because a lot of people have the habit of leaving the charger always installed to an AC outlet. Also notice the difference between this generic charger and the charger from Sony listed in the previous page, which consumed nothing. The higher consumption of this charger was probably due to its two bright LEDs that were turned on all the time.

Significant Consumption

Here are the equipment that you may want to consider start removing from the wall as from today. Each one of them consumes very little, below 10 W, but when we add them up you will see that the consumption is somewhat significant. You can also connect them to a surge protector and simply turn off the surge protector after you finish using your computer – because all equipment from this category coincidentally are computer parts. They are also equipment that a lot of people simply forget to turn off – simply because some of them like modems and routers don’t have an on/off switch!

The equipment that had a somewhat significant consumption when in standby or idle mode were the following:

As you can see, our computer is still consuming 1.5 W even when it is theoretically turned off!

Our laser printer has an on/off switch that really turns off the printer, but most people leave the printer on the “ready” status (i.e., turned on but idle) when the computer is on, and some even forget to turn it off after turning the PC off. But be careful, as we found out something really important. When we turn our laser printer on it heats itself up and runs its motors to see whether there is any jammed paper inside, a process that consumes a lot of power (around 300 W) during a short period of time. So it is definitely NOT advisable to keep turning on and off your laser printer just to try saving 2 W, as whenever you turn it on it will waste around 300 W during its initial heating and paper jam detection process. So if you are going to use your laser printer during the day, just leave it turned on. Turn it off only when you know for sure that you won’t use it for the whole day.

Modem, broadband router and computer speakers are components that almost everybody forgets to turn off, and the problem is that routers and modems do not have an on/off switch! So these equipment should be manually removed from the AC outlet or you should use a surge protector and simply turn the surge protector off after using the computer. Notice, however, that by doing this probably your modem will get a different IP address from your internet provider when you turn it back on. Several people leave their modems turned on so they can stay with the same IP address. For the majority of users this doesn't make any difference.

When we forget our speakers turned on it is still consuming a lot of power for an equipment that is doing nothing (7.5 W). And we also found something really annoying about our speakers: even with its switch on the off position it still consumes 3.3 W. Can you believe that? So our recommendation of connecting everything to a surge protector and turning it off after finish using the computer makes even more sense.

Huge Consumption

From our equipment only two really consumes a lot of power when are theoretically turned off:

A scaler – also known by other names like line doubler and upconverter – is a device that gets non-HD contents and converts them into high-definition. This equipment isn’t so popular because of its price, but all high-end home theater setups must have one of them. The problem with our scaler is that when it was “turned off” it was consuming only 1 W less than when it was turned on and working. This is insane.

But what was really hurting our electricity bill was something that everybody has at home: the cable TV converter box. Turned off this device was consuming the same amount of power as when it was turned on: 27.5 W. That is ridiculous. Of course we are talking about a specific model from Motorola and your converter may not have this problem.

Way before we bought our power meter we had the impression that our converter was wasting a lot of power, by the simple fact that it was hot even after 24 hours “turned off.” This was a hint that it was consuming a lot of power even turned off.

Because these two items are part of our home theater with these results we recommend everybody to use a surge protector with their home theater systems and turn it off after watching TV or a movie. This will save you a lot of money (in our case we were wasting over 40 W 24/7).

Note that if your cable signal is digital by removing your cable TV converter from the AC outlet you will lose access to the programming grid. When turning the equipment back on you will have to wait to up half an hour for it to download all channel information.

Conclusions

So what is the answer to our initial question – is it true that electronic equipment consume a lot of power when they are on their standby mode and presumably turned off?

The answer is: it depends on the equipment.

From what we’ve seen on our own (and small) research, the majority of equipment won’t be consuming anything at all when they are on their standby mode, or be consuming so little that is negligible – turning them off by removing them from the wall would have an impact of less than $1 on your monthly electricity bill.

But there will be equipment that will really consume a lot of power and our greatest villain was our cable TV converter, consuming 27.5 W when it is presumably turned off! Having this equipment connected 24/7 to the wall as it happens on the majority of homes – and with some homes having more than one converter box – will definitely make an impact on your electricity bill.

Remember, however, that if your cable signal is digital by removing your cable TV converter from the AC outlet you will lose access to the programming grid. When turning the equipment back on you will have to wait to up half an hour for it to download all channel information.

So almost all equipment won’t be consuming anything at all but because of just one of them you may have an increase on your electricity bill.

The main problem is how to know which equipment consume power when they are theoretically turned off. The best way would be buying (or borrowing from a friend) a digital power meter and make the measurements for yourself. Assuming that you don’t want to buy one or don’t have a friend that has one, another option is the temperature test: any equipment that is hot when it is turned off is consuming power. So just touch all sides of your equipment to check whether they are hot or not. Of course this shouldn’t be done after you used them, as they will be hot exactly because you have just used them. Try doing this in the morning, before anyone starts using them.

Or you can simply use the paranoid approach: remove all equipment from the wall (connecting them to a surge protector and turning off the surge protector) after using them!

We also made two important discoveries during our research.

First was regarding our computer speakers. When idle, i.e., with no sound being produced, it consumes 7.5 W. So it is not only important to turn it off after using the computer (a lot of people forget to turn them off), but also while you are using the computer try keeping them off when you are not using sound (i.e., not listening to music, not playing videos, not playing games, etc). The second discovery about our speakers was that they are consuming 3.3 W even when they were turned off!

The second major discovery was regarding our laser printer. Leaving it on its “ready” (idle) state consumes 2.1 W, but it is better to leave laser printers turned on than turning then on and off all the time, as every time we turn them on they start a heating process and paper jamming detection that consumes around 300 W. This is the only case which leaving an equipment on its idle state and consuming a little bit of power is a good thing – unless, of course, you won’t be using the printer for the whole day; then leave it off.

Originally at http://www.hardwaresecrets.com/article/How-Much-Power-Do-Electronic-Equipment-Consume-When-in-Standby-Mode/519


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