how to connect two switches in series to control a single load?
In today’s basic home electrical wiring installation tutorial, we will learn how to wire and connect two switches in series to control and operate a single light point.
For the most part, this is not an offered method of wiring single-way switches in series, since parallel or series-parallel connection is used in common electrical wiring installation. In some cases it may seem like a useless connection, but there are some possibilities where we need to control a single load from two places while both switches need to be on to operate the load.
- related post: how to connect switches in parallel?
Before going into details, we will look at the basic construction and operating mechanism of the single-way switch (2-way in North America) shown in the figure below:
Below is a simple step by step tutorial with schematic and wiring diagram showing how to connect one way switches in series?
- one way switches (spst = single pole single throw) x 2 no
- lamp (bulb) x 1 no
- short pieces of leads x 4 no
Connect the two one-way switches and the light bulb in series to the power supply as shown in the figure below. note that both switches s1 and s2 must be closed to complete the circuit.
if there are more switches connected in series with electrical appliances, i.e. light points, all of them must be in the on position to operate the load. if one of the individual switches is open, the circuit will not work.
click on the image to enlarge
The circuit will only be completed if both switches are in the on position. In other words, if one of the switches is open or in the off position, the bulb will not light. this is the same case for other loads that are connected in series to be controlled by two one way switches.
related wiring diagrams:
- how to wire a 4 way switch (nec) & intermediate switch as 3-way (iec)?
- how to wire single pole, single throw (spst) as 2-way & 1 way switch? IEC & nec
- how to wire single pole, double throw (spdt) as 3-way & 2 way switch? IEC & ne
The different positions of the one-way switches and the light point when connected in series are shown below.
click on the image to enlarge
To get the switching position in ON condition for the light bulb, the above operation is the same as the Digital Logic AND Gate truth table which is given below.
In simple words, there are four switch positions and if both switches are in the on position, the bulb will turn on. On the other hand, if one of the switches is in the off position, current will not flow in the circuit since the circuit behaves like an open circuit, so the bulb will not turn on. no matter what happens, all other connected switches are in the off or on position.
The following gif shows all the positions of the switches connected in series to a light bulb. It clearly shows that the bulb is on when both switches are in the on position. if any of the switches are in the off position, the bulb will not turn on.
here is the short version of the video:
- how to connect lamps in series?
- how to connect lamps in parallel?
good to know:
- Switches and fuses must be connected via a line (hot) wire.
- series switch connections is not a preferred way to wire appliances, a parallel or series-parallel wiring method is more reliable.
- less wires and cables are required in this type of wiring connection.
- not a reliable and convenient method of wiring.
- use this wiring connection only when necessary.
- electricity is our enemy, if you give it a chance to kill you, remember, it will never be missed. Please read all precautions and instructions while doing this tutorial in practice.
- Disconnect power source before servicing, repairing, or installing electrical equipment.
- Never attempt to work with electricity without proper guidance and care.
- work with electricity only in the presence of those persons who have good knowledge and practical work and experience who know how to handle electricity.
- read all instructions and precautions and follow them strictly.
- Contact a licensed electrician or power company before making any changes to the electrical wiring connection.
- The author will not be responsible for any loss, injury or damage caused by viewing or using this information or if you test any circuit in the wrong format. so please! be careful because it’s all about electricity and electricity is too dangerous.