Switch Gear Guide 2021: Circuit Breakers

If you have not heard about switchgear yet, then you need to start your research. Switchgear is an essential addition to your business to protect your expensive electrical equipment from damage.  

Circuit breakers are a form of switchgear. They are automatically operated and they behave they like the switches we use to turn lights on and off. However, instead of turning on/off when they are pushed, circuit breakers trigger when an excess of electrical current is detected. 

An excess of electrical current may occur as a result of faulty equipment within the circuit, a power cut or surge, or a short circuit. Circuit breakers detect this excess current and interrupt the current flow. This interruption protects electrical equipment further along the circuit from being affected by the overflow current.  

Passing excessive current through electrical equipment can severely damage it. This is the reason why we are advised to turn off larger electrical items connected to the mains during a power cut, to prevent damage from the power surge when the power comes back on. Circuit breakers do this automatically, and as part of the circuit, this is how they protect your equipment.  

Many businesses rely on computers and other electrical equipment heavily, and often a lot of it can be very expensive to replace. Circuit breakers help prevent replacements being necessary. This investment would save you a lot in the long term.  

Unlike a fuse, which conducts a similar function, circuit breakers can be reset. The reset can happen automatically or manually. Therefore, circuit breakers do not need to be replaced whereas fuses do. This means investing in a circuit breaker is the most cost-effective way to protect your electrical equipment because you do not have to replace the switchgear, nor the electrical equipment, in the event of an electrical current surge.  

Obviously, there are lots of variations of circuit breakers and, in this article, we are going to take a look at some of the main ones. 

Types of Circuit Breaker

A switch pole refers to the number of separate circuits that the circuit breaker controls. 

Type Abbreviation Definition 
Single Pole SP A circuit breaker which controls just one circuit 
Single Pole and Neutral SPN A circuit breaker which controls just one circuit, controlling only the hot side of the circuit. 
Double Pole DP A circuit breaker which controls two circuit 
Triple Pole TP A circuit breaker which controls three circuits 
Triple Pole and Neutral TPN A circuit breaker which controls three circuits, controlling on the hot side of each of the three circuits. 
Four Pole 4P A circuit breaker which controls four circuits 

What do Circuit Breakers Look Like? 

Circuit breakers are made in a variety of sizes.  

Small devices protect low-current circuits or sometimes individual household appliances.  

These miniature Circuit Breakers use air alone to interrupt electrical currents. 

Larger devices are designed to protect high-voltage circuits which can supply whole cities.  

Circuit breakers can terminate currents very quickly – between 30 and 150 milliseconds. This means circuit breakers act very quickly to protect your electrical equipment as wholly as possible.  

The generic, ultimate function of a circuit breaker, or a fuse, too, is to act as an automatic method of removing power (or electrical current) from  a faulty system. This is referred to as Over Current Protection Device, often abbreviated to OCPD.  

Circuit breakers are rated by two things: 

  1. the normal current they are expected to be capable of carrying,  
  1. the maximum short circuit current that they can safely interrupt.  

The latter figure will be conveyed to you via the circuit breaker’s AIC (Ampere Interrupting Capacity).  

Identifying the right circuit breaker for your specific needs may be overwhelming and confusing; that is where Energy Solutions can offer you assistance. We can advise you on your individual switchgear needs and requirements.  

How do Circuit Breakers work? 

Circuit breakers work alongside appliances, ground wires, and live wires to manage the electrical current in a building. The circuit breakers’ job is to cut off the circuit whenever it jumps above a safe level.  

Circuit breakers contain a switch, this means that it can be used more than once as the switch can just be reset. It is like your light switch; you can turn it back on (when safe to do so), it just automatically turns itself off. As aforementioned, the switch will be turned off should the circuit breaker recognise the electrical current which is passing through it to be too high.  

The Key Differences Between Fuses and Circuit Breakers 

Both circuit breakers and fuses act as switchgear which interrupts currents, but they do so in very different ways.  

Below is an overview of the differences: 

Fuses Circuit Breakers 
Replaceable Resettable 
Made of a piece of metal which melts when overheated by current, cutting off power to the circuit. Contain an internal switch which is tripped by an electrical surge, cutting off power to the circuit 
Tend to interrupt the current quicker Tend to interrupt the current slower 
Less expensive More expensive 
Prevents overheating Prevents overheating and electric shock 

Let us now take a closer look at the differences: 

Fuses 

Fuses stop electrical current because they typically contain filament, a thin piece of metal which connects the fuse to the electric circuit. This filament when it gets too hot. The melting of the filament breaks the circuit, and the electrical current can no longer pass through. An electrical current which is too high will be too powerful, creating a lot of heat energy which therefore melts the filament. Different types of fuses are designed to function with different levels of electrical current. When the level of current they are designed to function with is exceeded, that is when the filament will melt.  

Therefore, it is important that you are buying the correct type of fuses for your specific needs. There are different voltage and ratings available. Typically, it is advised that the best fuse option would be one which is rated slightly higher than the normal operating current within the circuit, just in case.  

Circuit Breakers 

Circuit breakers have two methods of working – the first is through the use of an electromagnet, and the second is through the use of a bi-metal strip.  

In either instance the breaker allows electrical current to flow across the metal conductor, connecting the circuit. However, when a current reaches an unsafe level for the electrical equipment within the circuit, the magnetic force of the magnet or the metal strip becomes strong enough to trip a metal lever. This metal lever throws the switch mechanism, breaking the current.  

An additional option for a circuit breaker is for the metal strip to bend. This action of bending throws the switch and breaks the connection, also. This protects the electrical equipment in the circuit by preventing the electrical current from affecting the equipment.  

Because circuit breakers contain a switch to turn off current access, the flow of electricity can be restored by just turning on/resetting the circuit breaker’s switch.  

In many domestic cases, circuit breakers are found in one space, often a cabinet, which contains a lot of individual switches (this is known as a breaker box). This allows for individual circuits to be switched off in different areas of a house, to allow for work or adjustment to wiring etc in that specific part. This is useful as it maximises the amount of the property which remains functional even during a maintenance period.  

Circuit breakers also include a ground fault circuit interrupter application. This function prevents electric shock, rather than only overheating/equipment damage. This feature is generally most useful for kitchen or bathrooms as electrical appliances tend to be nearer to water here, making the likelihood of electrocution higher should there be a power surge.  

Circuit breakers and fuses are not always interchangeable. For expert advice on which switchgear would work for your specific needs and circumstances, Energy Solutions are the best people to contact for impartial, expert advice on your energy queries.  

For more information about this post and how Energy Solutions can help with your Electricity, Gas, or Water, click on the links, or check out the contact details at the bottom of the page.