At the electronic level, tri-state buffers are often used to electrically disconnect the wires so that one device can be totally unaffected by what is going on in the bus, although it can be reconnected in nanoseconds by simply sending a signal to the tri-state buffers. Another type of connection is called a wired-or where a number of wires carrying logic values are electrically connected to a common wire. If one or more of those wires gets a high voltage, signaling logic 1, the common wire also gets a high voltage, thus getting logic 1. Since voltages are additive and since logic 1 is usually defined to be anything of +12V or higher, this makes a cheap form of OR gate.