In the same way that a switch in a two-wire control system may be used to manually regulate a load, a control device used to sense a change in pressure or physical position can be an automatic two-wire control system. Such devices include thermal and magnetic relays.
A two-wire control system must have a power source and a control device connected to each other by two conductors. These conductors are called "wires" because they must be able to carry current even when the connection between them is broken. A wire can be a copper conductor within a wall or flooring material or it can be a steel cable. The term "two wires" means that these cables connect a power source to one or more controlled elements. A third wire is required to connect the control device to the power source. This third wire is called the "grounding conductor" because it connects all metal parts of the system to ground. If this conductor is not present, anyone who touches any metal part of the system will get a shock.
All electrical systems have leakage currents flowing through themselves at all times. These currents flow through any available path, including from line to neutral or from neutral to line. A circuit is considered "broken" if neither line voltage nor neutral voltage is present. Leakage currents exist regardless of what type of load is attached to a system.
(1) In electrical engineering, a manual switch having two or more settings used to close and open electrical control circuits. They are often installed on control boards and panels and are utilized in automated and remote-control systems. A common type of control switch is the rocker switch, which has three or more positions that can be set by rotating it left or right. The rocker switch was originally designed for use with radio receivers but is now commonly found on light switches, television sets, and home appliances such as refrigerators. Switches may also be constructed using semiconductor components such as silicon chips or push buttons. These switches are known as solid state switches because they do not require any moving parts to operate.
Control switches are used to turn various devices on and off either directly or through another device. For example, a control switch could be used to turn on and off a lamp within reach of a person standing in a dark room. Or, a control switch could be used to turn on and off a water pump at a rural residence site. Control switches are also used in security systems, air conditioners, heat pumps, and other large appliances where the operator wants to make sure that only one item is turned on at a time.
The term "switch" means a mechanical or electrical device that opens or closes an electric circuit.
Two or more electric switches physically linked by moving arms or levers so that they can function at the same time or in a predetermined sequence... The term "linked" also applies to electrical circuits. If one circuit controls another, they are said to be linked.
Linked switches provide an alternative way to turn off lights in a room when you leave it while still being able to control them from another part of the house. Normally each light has its own switch, which is convenient because then you can shut off the whole room if needed. But sometimes you may want to let someone else take care of this task for you by linking the switches on all the lights together with wires. They can then work together as one group of switches instead of many separate ones. This is called a linked system.
Linking switches is easy to do. All you need is a pair of standard switches located in two different parts of the house. Then connect their black wires together and ground their third wire to create a single link between the switches. You can now control both switches from either one and turn off all the lights by using only one. The other switch remains locked out until you release it too. This is much easier than having to remember which lights are off and which aren't when you leave a room!