Electricity always wants to flow along a path to ground, and a path with the least resistance, ie. the shortest path and where there is no interruption to the path. So if a current flow can change its intended path to a shorter path, it will, because this is a shorter and easier route to ground. Therefore, a short circuit is when an electrical current flow travels down the wrong or unintended path, due to a fault that has occurred with the wiring and/or the circuit, and it is called a short circuit because this will be shorter than the intended circuit path.
What are the effects of a short circuit?
Short circuits are the most common cause of electrical issues in the home or workplace. Unless you have protection within the circuit itself, the short circuit could create a spark in the electrical circuit or panel.
This spark can cause an electric shock to someone who comes into contact with the spark, this is because the human body then becomes part of the circuit. The electrical current flow takes the path of least resistance, and if you touch the wire with electricity running through it, that path is through your body. This is why you should always build protection into a circuit to shut it off immediately when a short circuit occurs, and why you should always switch off the electrical supply to a circuit before you attempt to touch it or work on it.
Another common effect of a short circuit is fire. Any spark created by a short circuit can cause arcing and can ignite material it is in contact with, so this could be other wires in a circuit which can very quickly develop into a full scale fire.
When a short circuit occurs, in most cases a device will shut off and lose power. So you might see this as a device immediately not working, but this may also trip other items within the same circuit. So in a kitchen, for example, you may also lose power to a cooker, plug sockets and lights.
How are short circuits caused?
There are various common causes of a short circuit which enable a current flow to take an unintended path, these include:
- Liquid – Exposed wiring comes into contact with water or another form of liquid
- Wire contact – The live and neutral wires come into contact with each other, this could be caused by a faulty wiring connection, a loose connection or faulty insulation
- Damage – A puncture to the wire casing caused by a nail or a screw, this can also occur when pets or rats/mice chew a cable
- Surge – A build-up of excessive current flow to abnormal levels
- Old appliances – Malfunctioning appliances with damaged cords or plugs can cause a short circuit, as anything plugged into a wall effectively extends the circuit.
How to guard against short circuits
There are a number of different mechanical devices which can be incorporated into a circuit design with the express purpose of preventing short circuits. The three most common devices are:
- Circuit breaker or fuse – These detect a change in electrical current flow and break the circuit connection when this irregularity occurs. Circuit breakers are effectively a modern alternative to the fuse. A circuit breaker can be reset to use again on the same circuit, while a fuse is a one-off protection device that would need to be replaced.
- Residual Current Device – Known as an RCD, this is similar to a circuit breaker in that it senses changes to current flow, but is much more sensitive than a circuit breaker and automatically shuts off at the slightest fluctuation in current flow.
- Arc-fault interrupter – This device protects against arcing, which occurs when a loose electrical connector causes electricity to jump between two metal contacts.
If any of these devices regularly trips immediately after being reset, then there is a wiring problem somewhere in the circuit or within the appliance it is connected to, and this should be immediately investigated because it will continue to short circuit until the problem is rectified.
Video Demonstration
Below is a product demonstration video of the TIS 870 Digital Circuit Breaker Finder & Socket:
Please note that this section is for information purposes only. Anyone using equipment referred to in this section must be suitably qualified and/or experienced within the respective field. If in doubt before use, please consult a qualified electrician or engineer & thoroughly read all instruction booklets.