What is Overloading?- Reasons, Effects, and Prevention

Last Updated on December 29, 2023 by Electricalvolt

Definition: The circuit drawing more current than its rated current carrying capacity is said to be in the state of overloading. The power circuit is designed to carry the specified current. The current flowing in the circuit depends on how many electrical appliances of different power ratings are connected to the power source. Therefore, the more power loads are connected to the circuit, the more current will be drawn.

At the design stage of the power circuit, the power-controlling equipment, such as fuses, circuit breakers, and MCBs, are designed. The wire size is selected according to the load current. All these are done to ensure that there should be no overloading when all the connected loads are in operation.

You must ensure that the electrical circuit does not draw more current than its rated capacity. Otherwise, it may cause socket heating, wire burning, and fire hazards.

Have you ever heard of the term “full load current” (FLC)? It is commonly used when referring to equipment such as motors, heaters, and generators. Essentially, FLC refers to the maximum amount of current that the winding of the motor or heating element of the heater can safely carry.

What happens if a current that exceeds FLC flows through the winding? When this happens, excessive heat is generated, which can cause I2R losses, insulation failure, and even fire hazards. Keep in mind that the insulation’s lifespan depends on the temperature, so it’s important to ensure that the current flowing through the winding remains within safe limits.

electrical-overloading

You may have come across the term “current carrying capacity of wire”. This refers to the maximum amount of electrical current that a wire can handle without overloading and causing insulation failure. For example, if a wire is rated to carry a maximum of 10 amperes and a load connected to it draws 15 amperes, the wire will become overloaded and potentially cause damage.

If you notice any discolored outlets or wall plates, burning smells, flickering lights, sparks, arching, buzzing sounds, or appliance malfunctions, these may be symptoms of an overloaded electrical circuit.

The safe operation of the electrical system requires avoiding overloading electrical equipment beyond its security limits.

Reasons for Electrical Overloading

The most common cause of overloading is when extra loads are added to the electrical circuit, which can exceed the current rating of wires, MCBs, and other electrical equipment.

  1. Connecting multiple electrical loads on the same power socket may cause overloading and heating of the power socket.
  2. Inadequate design of the power circuit: If the circuit is not suitable for carrying a large current, it will cause wires to overload. You need to re-design the electrical power distribution system.
  3. The circuit must be designed considering harmonic load rather than only linear load. Nonlinear loads, like electronic types, draw more current, and harmonic current can overload the circuit.
  4. The power supply can experience undervoltage and overvoltage, which can lead to increased current delivery for the same power. If you notice significant supply fluctuations, it is recommended to use a voltage stabilizer.
  5. Voltage sags, swells, surges, transients, and other power supply disturbances can cause overloading.
  6. If a reactive management system is not used, it can cause an increase in current and result in overloading.
  7. Proper distribution of electricity is crucial in managing circuit load. Improper supply distribution leads to overloading of the circuit.
  8. Defects in equipment and wiring can cause overloading.

Effects of Overloading:

Electrical overloading has several adverse effects on electrical systems, equipment, and devices. Here are some potential effects of electrical overloading:

  1. Overheating
  2. Voltage Drops
  3. Equipment Failure
  4. Fire Hazard
  5. Damage to Electrical Components
  6. Reduced Efficiency
  7. Voltage Instability
  8. Power interruption

After learning about the causes and effects of electrical circuit overloading, you can take the following steps to prevent it.

How to Prevent Overloading?

Ensure the safety of your electrical systems and avoid overloading by following these guidelines.

  1. Know the apparent power electrical capacity (kVA) of the electrical installation.
  2. Check Appliance Ratings and sum all the equipment ratings in kVA.
  3. Calculate the current for each circuit.
  4. Calculate the ratings of circuit breaker, fuses, and wire size
  5. Install rated capacity switchgear and wiring.
  6. Distribute Loads according to the circuit’s current carrying capacity.
  7. Install fuses, Earth leakage circuit breakers(ELCBs), circuit breakers of appropriate ratings,
  8. Regularly Inspect Wiring by taking the insulation resistance test.
  9. Install capacitor banks for power factor improvement. It will reduce the current. If the load current is varying, you can install an automatic power factor control (APFC) panel.
  10. Install Miniature circuit breakers(MCBs)

Conclusion:

In this article, you have learned the definition of overloading, the concept of overloading, the reasons behind it, the issues it can cause, and how to mitigate those issues to ensure safety. By keeping the electrical loading within the permissible limit, the associated hazards can be minimized, and safety can be enhanced.

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About Satyadeo Vyas

Satyadeo Vyas, M.Tech,M.B.A. is an electrical engineer and has more than 36 years of industrial experience in the operation, maintenance, and commissioning of electrical and instrumentation projects. He has good knowledge of electrical, electronics, and instrumentation engineering.

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