HomePlug® networking is a way to carry data over a powerline such as a home power network. Its most common use is to create home computer networks without the need for additional cabling or wireless signals. HomePlug® itself is a brand name and the name of an industry standard for the system.
When using HomePlug® networking, you should be able to route data signals between any two power sockets which are connected to the same electricity meter. In practice, the connection speed works out around half that achieved by a wireless network. This should be enough for most home internet use. A HomePlug® signal should be able to travel up to 328 feet (100 meters) without degrading, so will be adequate for virtually all homes.
Around 70 companies are members of the HomePlug Powerline Alliance, a trade group which promotes products under the HomePlug brand. The companies also use an agreed set of standards. This means that all products marked as HomePlug® will be compatible with one another.
There are some factors which can limit HomePlug® networking. The signal can be subject to interference from some devices such as surge protectors. For this reason it is normally best to only use HomePlug® devices by plugging them directly into a socket rather than through an extension cord or multi-socket adaptor. Homes in the United States which use the split phase power system may not be able to use HomePlug® networking throughout the entire building.
Data sent through HomePlug® networking has a small but significant security risk. This is because the signal may pass outside the borders of the building concerned. To protect against this, HomePlug® equipment will encrypt the data by default. However, there is usually no danger of a neighbor being able to intercept your data simply by using their own HomePlug® equipment.
The concepts and technology used by HomePlug® networking can be applied to other forms of data transmission. For example, it’s possible in theory to transmit broadband internet signals over the power lines to a home. Where this works, a user simply needs to plug a suitable modem between a computer and a standard power socket to get an internet connection. In practice there are several interference problems which make this system difficult to use reliably.