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13 Dec 2023

What Is A Shunt Trip?

A shunt trip breaker is a type of circuit breaker that, in addition to automatically tripping during an electrical surge and cutting off power, also can be triggered by a separate electrical signal to disconnect before a power surge occurs. A shunt breaker has three connections: to the power source, the output, and a third contact usually hooked into a safety system such as a smoke detector.

How Do They Work?

Shunt trip breakers offer an added degree of protection against power surges, and although they serve a similar purpose to regular circuit breakers, they work somewhat differently. A circuit breaker will automatically trip when it finds fault, cutting power to the circuit to avoid issues like overheated wiring. 

The breaker trips off when the currents surge too high, causing the electromagnet underneath the main breaker to charge, which triggers the switch and cuts power to the system. On the other hand, a shunt trip breaker offers extra protection. 

It offers an alternative method to charge the electromagnet, which triggers the switch. This enables you to remotely or automatically trip the breaker and cut power in an emergency. 

There are a few different types of shunt trip breakers, automatic and manual, each of which features a slightly different setup. However, despite the variation, they work similarly. For example, some shunt trips tether to an external power source. So, when the power surge reaches this source, it sends a signal to the main breaker, causing the power to shut off automatically. 

Other shunt trips connect to a remote switch on the building’s exterior. To cut power via the shunt trip you simply press the button on the switch to send the electrical surge through the shunt trip wiring and cut the power. 

Where Are Shunt Trip Breakers Used?

Although shunt trip breakers are an optional accessory for buildings, they offer an added layer of security, so many individuals choose to install them. Generally, the local building code views these as an optional addition, so you technically don’t need to incorporate them into your project. 

However, it doesn’t hurt to incorporate them, especially if the building contains expensive machinery or equipment like in an industrial setting. In addition, adding a shunt trip can easily cut power to the building if necessary in an emergency.

Aside from large warehouses and facilities housing high-end industrial machinery, many businesses feature shunt trip breakers as a safety precaution. 

Shunt trip breakers are often used in concert with sprinkler and other fire suppression systems that can potentially short-circuit electrical appliances. The shunt breaker is connected to the fire detector or alarm, so that when the alarm is triggered, the breaker is automatically tripped, cutting the power to any computers, electronic locks or other electrical equipment before the sprinklers can soak them in water.

Why Are Shunt Trip Breakers Important?

Despite the optional nature of shunt trip breakers, they can be an essential safety device in an electrical system. As a result, many electricians incorporate these breakers as an added layer of security because they can prevent injury and damage during power surges or other emergencies.

These breakers are helpful on multiple fronts, but one of the most common ways people use them is during a fire. By turning off the power when a fire breaks out, electrical hazards are no longer a significant risk. 

Others connect the shunt trip to smoke alarms in their homes, so the power automatically turns off when the detectors trigger an alarm. Of course, this might not be sensible in some cases, as sometimes the smoke alarm goes off due to steam from the shower or smoke from the kitchen. 

However, continuing with the same example, connecting the shunt trip breaker to a smoke alarm is wise, especially when a sprinkler system is involved. The device will cut power to your building as soon as the smoke detectors trigger the sprinkler system, which helps reduce the risk of electrocution. 

The Bottom Line

A shunt trip is optional to your building’s electrical system and is designed for additional protection and safety. The system helps mitigate damage to electrical equipment due to power surges, lessen the chances of personal injury, and avoid electrocution hazards if a fire breaks out. So, although shunt trip breakers aren’t required, incorporating them is not a bad idea!


If you need help installing a shunt trip, Bay Power is here to help. Contact us today for all of your electrical component needs. 

Shunt Trip Breaker product link: Shunt Trip Breaker TRMF2-125T MCCB 125Frame/3P 15A up to 125A (

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