A cross-over stair switch is a single-key switching device that allows you to control two groups of light points (lamps) or any other electrical appliances from different places. It is mostly used in staircase wiring, as well as in rooms, halls and large premises that have two entry and exit gates.
The basic idea of the cross-over stair switch is to provide a complete circuit for current to flow and a bulb to light when both switches are on, but to break the circuit if only one is on. This design is similar to a three-way switch, but it uses fewer wires.
When a three-way switch is connected, its three terminals are usually named COM, L1 and L2. Sometimes, they’re called 1 Way, 2 Way or even just ‘Way’. The first terminal is connected to the line (Phase) wire, and the second terminal is connected to the neutral wire at ground potential. The third terminal is normally not connected, but it’s a good idea to make sure that this is the case as it could cause an electrical shock.
3-Way Wiring and Logic Gate Truth Table
The standard 3-way switch connection method is based on a logic gate, also known as an exclusive-NOR gate or Ex-OR gate. This logic gate is very similar to a standard digital circuit, as it allows the status of the lamp or other electrical appliance to depend on the COM terminals of both switches that are connected to their respective L1 and L2 terminals.
To connect the circuit using this switch, the first COM terminal of each switch must be connected to its own L1 terminal and the other COM terminal of each switch must be connected directly to their own L2 terminal. This connection is commonly referred to as a ‘Break Before Make’ design, because the first connection must be broken before the second one can be made.
This is a great way to avoid the “dangling switch” problem that’s all too common with three-way switches. It’s also an effective way to reduce the number of wires that are used for the circuit, and thus save money on your electrical bills.
In addition, the switch can be positioned so that it only affects the current that is coming through to the load from the line wire and not the other circuit wiring. This is especially useful when the switch will be in close proximity to a light bulb, which could potentially be damaged by too much current flowing through it.
It’s a good idea to always install your switches with a grounding screw, as this is an important part of the safety of your home or commercial facility. The screw is often located on the metal strap of the switch, but it may be on a side or another location as well.
To test the three colored wires in each box for voltage, use your multimeter and touch one probe to a known ground, such as a metal outlet box or a bare ground wire. If you don’t get a reading, then the box is not grounded and should be replaced.
