Circuit Breaker Keeps Tripping. Electrical Causes

June 2024

1) What is a Circuit Breaker?

A circuit breaker is a device inside an electrical panel or consumer unit that prevents an overloaded circuit from occurring. 

The circuit breaker keeps the flow of electricity (or electrical current flow) to a limited level and will disconnect the power supply if there is too much current. 

They are small devices and have a switch on the front of them along with some printed text to allow us to see what type they are, their rating and other useful additional information. 

2) How to tell if the Breaker has Tripped?

As each circuit breaker has a switch on them, if a circuit breaker trips it is easy to tell which one is the tripped circuit breaker. The service panel will have several switches that are sat in a particular position with the tripped breaker in the opposite position. 

The circuit breaker box is normally found at the same position as the incoming electrical supply, electric meter, and other electrical equipment. This could be anywhere in your home including the garage, under the stairs, the basement (or cellar) or near the front door. 

3) Why does a breaker trip and how?

If your MAIN breaker has tripped then this is likely to be a different fault which you can read about here.

The circuit breaker monitors the circuit supply wire also known as the hot wire, the live wire, or the line conductor. When excessive current is present the circuit breaker will trip using one of two methods:

Gradual overload resulting in a Bi-Metallic strip bending away from two electrical contacts inside the circuit breaker 

AND

Short Circuit conditions where a very large fault current occurs in a circuit resulting in quick operation and the disposal of an electrical arc within the circuit breaker.

3.1) Gradual Overload

Where there are too many electrical appliances or electrical devices being used on the circuit at the same time, the circuit breaker will allow more than its rated current to flow for a short time before tripping gently to the off position. 

Once the Bi-Metallic strip inside the circuit breaker has sufficiently cooled, it will return to its original position once again touching both electrical contacts and allow the circuit be re-energised. 

3.2) Short Circuit

Where the Hot (Live) wire comes into contact with Neutral wire in the case of an appliance, cable or junction shorting out, a sudden power surge will cause a large circuit overload and result in a massive electric current flowing. 

Where this occurs, the Bi-Metallic strip does not bend but a solenoid operates to disconnect the circuit more quickly. 

4) Checking the Electric Panel or Fuse Box

Make sure to keep a battery powered torch near the breaker panel or fuse box in case of emergencies to allow for easy viewing of the circuit breakers. 

Where there is a switch in the DOWN or OFF position, this indicates that the circuit breaker has tripped. Make sure to unplug all the appliances on the circuit that has tripped before attempting to reset the circuit breaker.

Try resetting the circuit breaker by pushing the switch quickly into the ON or UP position. If the circuit breaker immediately trips back off again, consult a professional electrician to come and check for any problems. 

Circuit breakers help prevent electrical fire along with other electrical problems so it’s not wise to continually reset a circuit breaker. If a circuit breaker is continually reset without the cause being investigated, then further damage can occur to the circuit wires and the home’s electrical system. 

5) 9 Common Reasons why trip switches and breakers trip

The circuit breaker is very effective at preventing an electrical circuit from overheating or becoming damaged through excessive fault surges but it does have its limitations. For this reason, often the home’s circuit breakers alone are often not adequate to prevent damage to the home’s wiring and we need other protective devices in the consumer unit. 

There are different types of protective devices that trip protect against various electrical faults:

• GFCI (Ground Fault Circuit Interrupter) or RCD(Residual Current Device) – This device protects against earth faults, electrical shock, cable insulation faults and more. 
• AFCI (Arc Fault-Circuit Interrupter) or AFDD (Arc Fault Detection Device) – This device protects against electrical arcing and offers further protection against possible electrical fires
• SPD (Surge Protection Device)
• 

(A Surge Protection Device (SPD) in a consumer unit: Right Hand Side)

All these devices are collectively known as trip switches or protective devices. There are several common reasons why these devices would trip:

1. Earth Faults
2. Short Circuit
3. Faulty Appliance
4. Electric Shock
5. Overloaded Circuit
6. Faulty Wiring
7. Water Ingress
8. Electrical Arcing
9. Loose Connections

1 – Where there is electrical current flowing away to earth, this will usually trip an AFCI or a GFCI device. In systems where there is no AFCI or GFCI a sufficient electrical current would be needed flowing to earth to trip a circuit breaker. 

2 – Short Circuit conditions will trip a circuit breaker, AFCI or GFCI. Where damage occurs to a cable such as a nail being hammered through in a wall, a large electrical current will flow and be dealt with by one of these protective devices in the electrical panel.

3 – Faulty Appliance issues can result in electrical disruption. A toaster is a common kitchen appliance that can cause trip switches to trip. In the UK there are fuses contained in the plug tops of the appliance and under certain electrical fault conditions, the fuses will blow. It is more likely that the electrical panel will trip the circuit instead as the panel tends to be more sensitive. 

4 – Electric Shock can occur when appliances go faulty, minor cable damage occurs or where wet hands touch electrical parts. Under these conditions only a tiny electrical current will flow through a human body BUT it is nearly always sufficient to be detected by a AFCI or GFCI device. 

This device will disrupt the particular circuit from which the shock has been received. Great care should be taken resetting a switch after an electric shock. It is wise to consult a qualified electrician to check things over before resetting a device at the consumer unit or electrical panel.

5 – An overloaded circuit  is a result of too much electrical load being placed on the circuit. The most common reasons for this are poor circuit design resulting in too many appliances being used at the same time.

Kitchen socket outlets are a common source of overloading in homes. There are many large appliances and high-power devices in the kitchen environment that can result in excessive electrical power demands on the circuit. 

6 – Faulty Wiring can trip almost any electrical protective device in the consumer unit or electrical panel. Wiring can go faulty at any time but in older homes this can be a result of an aging cable network with degrading cable insulation being the most common cause. 

In newer homes, a faulty wiring problem is more likely to occur behind an electrical outlet, switch, or junction than on a section of electrical cable itself. 

7 – Water ingress is a very common cause of electrical problems. Outdoor security lights are a common failure point.Where a modern electrical panel is installed, it can often detect when water has entered an outdoor junction box, electrical socket or lighting system and will turn the supply off to prevent damage and electrical shock.

8 – Electrical Arcing is a situation where damage to cabling or loose connections can result in a very high resistance to current flow. The crackling sound that is heard from arcing is electricity jumping the gap and breaking down the resistance of the air. The temperatures generated from this situation can easily cause a fire.

9 – Loose connections are a common cause of plug sockets burning out and can lead to electrical fires occurring especially where the electrical panel or consumer unit is very old. 

6) Summary

There can be many causes for a circuit breaker that keeps tripping. If there is a noticeable burning smell occurring at the same time then its best to call a licensed electrician immediately to investigate the problem.

A loose connection is one of the most common reasons for excessive heat and a burning smell occurring. Whilst a tripped breaker results in an inconvenient and temporary power outage, its important to understand the reasons why, the electrical hazards that could be present and the right safety measure to take.