Stamp Out Wall Warts

The term Wall Wart refers to the small transformers we plug directly into an AC power receptacle that provide a low voltage (at relatively low current), often DC, for a small eletrical appliance such as a telephone, an answering machine, etc.

These little transformers have proliferated in recent years as many appliances have become available that use only modest amounts of energy to operate. On one hand, it is a good thing (in terms of energy use) that appliances consume modest amounts of energy. On the other, these little transformers have several bad features:

• They occupy a socket, making it unavailable for other purposes.
• They are always on, even when the device they supply is off, because they are plugged in, and unavoidable losses due to resistance in their coils consume small amounts of energy, dissipated as heat.

This latter point is becoming quite a serious problem. If the average westerner were to go through their house, adding up the watts consumed by all of the small devices that are operating or on standby 100% of the time, we would find that the energy consumption is surprisingly high. It is not at all hard for a typical middle-class household to exceed 100W of constant 24x7 power consumption. The reason this is a serious problem is that it is largely unnecessary. Most of this energy is therefore wasted.

If all of the devices that are always on in this manner could be truly OFF (i.e., consuming zero power) when not in use, the energy savings would be very large. And this is not really very difficult. It would require a true disconnecting power switch, as a first step. Next, since some devices really do require clock circuits to be on all the time, these could be powered by rechargeable batteries that are themselves recharged when the device in actually turned on. In some cases, where the device is used too infrequently, it may be necessary to power the clock circuit with a lithium cell or similar.

One disadvantage of this idea is that it would not be possible to turn devices on by remote control. Is that really a horrible inconvenience? Just about the only device that might have to be on all the time is a clock with a luminous display.

The next step would be to eliminate the wall warts by having a set of power wiring in the home carry 12VDC. So many devices now operate at these low voltages that this is becoming useful. Imagine a receptacle with, say, two conventional AC sockets (be they 230VAC/50Hz, 120VAC/60Hz, or some other), and four, six, or eight small sockets that carry 12VDC.

It is not even necessary to run extra wiring in existing installations. The 12VDC can be superimposed on the AC current on the existing pair of conductors, and the two supply voltages separated at the receptacle.

Alternatively, receptacles could contain the little transformers (with a voltage selector switch for each socket). They could be turned on by a load-sensing switch so that they would only be connected to the AC when their load device was actually turned on.

Simpler than replacing receptacles would be to market a device with a power cord, containing the DC power supply and an array of small sockets (possibly with voltage selector switches). This, like the receptacle with transformer, should have a current-sensing switch to disconnect power when no devices are operating. But in new installations, it may be preferable to run separate wiring for the AC and DC supplies.