Phantom Loads

Richard Perez

Just because the switch says "OFF" doesn't mean a device is not consuming electric power. Many modern appliances contain clocks, memories, remote controls, microprocessors, and instant-on features that consume electricity whenever they are plugged in. That's 24 hours a day, 7 days a week While these Phantom Loads are often small, their power consumption really adds up. Some Phantom Loads are easy to spot — clocks and and timers have displays. Other Phantom Loads are truly hidden: the appliance seems off when it is switched off, but it really isn't

My introduction to the phantoms...

I first became aware of the impact of phantom loads about five years ago. At the time I was working as an installing dealer of RE systems. I had a call from a customer complaining that his brand new batteries weren't working. Immediately after installation, the family went on vacation for three weeks and returned to fully discharged batteries. I made a service call to the site and investigated. After questioning it was apparent that the family had mistakenly left their inverter up and operating during their vacation. But since all the appliances were switched off, this couldn't explain where the two kilowatt hours of daily PV energy went. I questioned the family further, "Did you add any new appliances to the system?" "Yes," they replied, "we bought two new TV sets and a new stove with electronic ignition." And the hunt was on!

While the two 21-inch color TVs looked great, both were equipped with remote controls and "instant-on" picture tubes. A quick measurement determined that each TV was consuming 28 watts even when switched off. Most of this power was keeping the filaments in the picture tube warm 24 hours a day. A quick go with the calculator gave us a total inoperative TV power consumption of 1300 watt-hours daily. Measurement of the stove showed that the power supply driving the electronic ignition was operating 24 hours a day and consuming 14 watts. So the stove was consuming about 330 watt-hours daily, even when no one was cooking. Since all these appliances were powered via an inverter, the actual power consumption was even higher due to inverter inefficiency. I figured that the two TVs and the stove were consuming about 1,900 watt-hours of power daily. And they weren't even being used!

Obvious Phantom Loads

Consider a clock. Many microwave ovens, washing machines, stoves, VCRs, and other appliances contain a clock or timer. The electronic clock/timer and its display consume very little («0.5 Watts). However, there is a power supply in the appliance that converts 120 vac into low voltage DC for the clock/timer. This power supply is very inefficient at low power, consuming many times the power actually used by the clock. This power supply consumes between 4 and 8 Watts or about 100 to 200 Watt-hours daily — enough to run a compact fluorescent light for about ten hours.

Sneaky Phantom Loads

Some Phantom Loads appear to be truly OFF when switched off. There are no lights or indicators showing power consumption, but the device is still using electricity. Offenders in this category include instant-on TVs, stereos, VCRs, computers, calculators, computer printers, satellite TV systems, and any device powered by a "wall cube". Wall cubes are power supplies in plastic boxes that plug into 120 vac outlets. Let's visit a few of these Phantoms where they lurk.

The Primary is Alive!

Many 120 vac appliances contain power supplies. These convert 120 vac, either inverter or grid produced, into low voltage DC for the appliance's electronics. On some appliances the ON & OFF switch is placed on the secondary (low voltage side) of the supply's transformer. The primary is not switched and is always connected to the 120 vac source. See the diagram below.

120 vac

120 vac

plug

The inverter or commercial power grid sees the primary of the transformer as a constant load. Power consumption on these devices may run between 50 to over 200 Watt-hours daily.

Filters and Line Conditioners

Many 120 vac business appliances like computers, printers, typewriters, FAX machines, and copy machines use small filters on their power input. These filters serve a useful purpose — protecting the device from overvoltage, surges, noise and other electric trash that may wander onto the grid supplied electrical lines. Unfortunately, most of these filters are wired in ahead of the power switch, and are online all the time. They consume power from the inverter — about 8 to 40 Watt-hours daily. True power conditioners like ferroresonant line conditioners made by Sola, LineTamer, and many others can also be Phantom Loads. For example if a 500 watt power conditioner is used to filter inverter power for a computer system, then the filter will consume about 250 watts even if the computer system is unplugged from the filter.

Wall Cubes

These small black boxes are really Phantom Loads. Wall cubes are actually small power supplies. Consider the case of a telephone answering machine powered by a wall cube. The wall cube is plugged into an electrical outlet and feeds the answering machine via a low voltage power cord. The ON/OFF switch is located on the answering machine itself. Even if the answering machine is turned OFF, the wall cube still consumes electricity. This is electrically the same as having a power switch on the transformer's secondary — the primary is alive all the time. A wall cube uses 20 to 50% of its rated power even when its device is switched off.

Dealing with Phantom Loads

Unplug the appliance! This works for sure because it is disconnected from its power source. However, constantly plugging and unplugging is a pain and wears out the plug and socket quickly. Just about every hardware or discount store sells extension cords with multiple female plugs that are switched on the plug strip. They sell for $4 to $8. When the plug strip is switched OFF, all the appliances plugged into the strip are disconnected from the 120 vac power source.

We use these plug strips for all phantom loads. Here on Agate Flat, we have many SL Waber (Model EP7S, costing $5.99 at the local discount house), seven outlet, plug strips with neon indicator lights. The neon indicator glows when the plug strip is turned ON and supplying power to all the phantom loads connected to it. We have all our computer equipment, all remote controlled electronics (TV & VCR) and many wall cube powered devices plugged into these strips. I don't mind feeding these appliances when they are actually operating, but I don't want them wasting power and flattening our batteries when they are supposed to be OFF.

Selecting Appliances that are NOT Phantom Loads

Any appliance with a built-in electronic clock or timer is a constant and obvious phantom load. If you want a clock, then buy a clock, not a microwave or VCR. Avoid appliances with electronic memories unless these memories are kept alive by small batteries within the device.

In many cases all appliances of a particular type are phantom loads. VCRs, for example, all contain clocks and timers that are alive even if their displays are not lit. All appliances using wall cube power supplies are phantom loads. Every piece of electronic office equipment is a micro phantom load because of its filtration. Here the switched plug strip comes to our rescue.

The Bounty on Phantom Loads

If you live on the commercial grid, you're paying an average of 7.750 per kilowatt-hour for electricity. A small phantom load of 4 watts costs you about $2.70 yearly.

If you make your own electricity, then the savings situation is even better. Site produced power costs much more, about 600 per kilowatt-hour. The 4 watt phantom load costs home power producers about $21 per year. The plug strip pays for itself in less than 4 months. And we get to use our power elsewhere.

The bottom line for an individual phantom load tells only part of the story. Sure we can save some money by disconnecting phantom loads. We can also save resources for use elsewhere. We can also eliminate the pollution produced by the power going down the throats of phantom loads.

Regardless of the electrical power source, phantom loads waste energy because they don't do anything in return for their power consumption. While in the individual sense, these phantom loads are small, in the collective sense, we're wasting enormous amounts of electricity.

Let's do a little calculator speculation about phantom loads. A homestead powered by PV or wind can face between 1 to 2 kilowatt-hours of extra energy consumption from phantom loads. That's roughly equivalent to the energy produced by four to eight photovoltaic modules at a cost of around $350 each. Add also extra batteries to power the phantom loads at night. When you're making your own electricity, phantom loads are the enemy! Break out the plug strips and launch a direct frontal attack!

On a more serious, grid-connected note, our nation wastes about 43 billion kilowatt-hours of energy on phantom loads yearly. The spread sheet above shows how this was calculated. This is enough electrical energy to totally provide the countries of Greece, Peru, and Vietnam for one year. When I consider that this energy does nothing but waste power and produce pollution, I am ashamed.

Access

Author: Richard Perez, c/o Home Power, POB 520, Ashland, OR 97520 • 916-475-3179

Artist and renderer of the Phantom Load Demon: Stan (the pixelating pinhead) Krute, c/o Home Power, POB 520, Ashland, OR 97520 M-

ENERGY CONSUMPTION IN PHANTOM LOAD APPLIANCES The Small Picture The Big Picture

1 household 93,347,000 households

Quan

Phantom Load Appliance

Watts

Watt-hrs. per day

Equipped

millions of KWH per year

0 0

Post a comment