MCB vs. MLO: Choosing The Right Electrical Panel

When to employ one generally drives the debate between MCB vs. MLO. You should have a solid understanding of MCB and MLO before doing this.

The panel’s primary current device is the Main Circuit Breaker (MCB), the panel’s controller for all branch circuits. A complete property’s main breaker panel frequently has its own main breaker and provides energy to the whole panel. In the event of an overload or a short circuit on the power grid, it instantly shuts off the power circuit.

Main Lug Only (MLO) is typically used after a main circuit breaker panel, also known as a sub-panel. There is no primary overcurrent device in the panel for main luggage, only loading centers because the incoming wires terminate on the line side of the journeys and are hooked directly to the bus.

Let’s now compare all the advantages and disadvantages, applications, and features of employing MCB vs. MLO.

MCB vs. MLO: What Does MLO Mean Electrical Panel?

MLO load centers, frequently referred to as subpanels, are typically deployed downstream of a main circuit breaker panel. Supply connections from a panel with the main circuit breaker must be connected directly to the main circuit breaker.

All branch-fed devices are provided with over-current protection by the main circuit breaker, which also acts as a single disconnect point for all loads fed by the panel.

MLO panels, called secondary or add-on panels, are often installed after a main circuit breaker panel. MLO panels lack a primary overcurrent device and have lines directly connected to the incoming cable bus that terminate on side bullets.

What is an MCB Panel?


An MCB is an electromechanical device that guards electrical cables and loads against overcurrent to avoid fire or electrical hazards. In any abnormal situation of the electrical network, such as overload and short circuit circumstances, the MCB instantly shuts off the electrical circuit. Even though the MCB can be reset, the fuse can sense these circumstances and needs to be replaced.

The primary reason MCBs are utilized in place of fuses in many circuits is due to an automatic switch that opens when an excessive amount of current passes through the course and allows it to be closed again without needing to be manually replaced. In addition, using a bi-metal-related theory, MCBs protect against overload current and solenoid short circuit current.

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MCB vs. MLO 

Main Similarities Between MCB vs. MLO

  • The MCB and MLO can be surface mounted or flush-mounted.
  • Both are different types of load centers that protect branch circuits from electrical dangers, including arcing and ground faults.
  • Both connected circuits in your home receive regulated and distributed power.

Main Differences Between MCB vs. MLO

  • MLO is not the main breaker; it is merely an addition. As a result, it can be unplugged independently of the meter.
  • The primary circuits of your property are controlled and protected against overcurrent by MCBs. Instead of doing that, the MLO functions as a sub-board to aid in power distribution and boost the number of circuits.
  • As many circuit breakers as an MCB can support may be installed. An MLO, on the other hand, might only have 2–6 circuit breakers.
  • MLO has an amperage range of 125-800 amps, whereas MCB contains 125-600 amps.
  • An MCB’s neutral and ground strips can be connected, but an MLO needs its own neutral and separate ground strips.
What’s the Difference between MLO and MBR Panels???


In addition to safety, the area you plan to power might help you decide between the two. An MCB should be installed in a garage or basement with low activity. The MCB is in a prime location for those who live in apartments. Therefore using MCB is better compared to MLO, depending on the location.


In this category, MCB beats MLO. The MCB guards against excessive current and heat. MLO, in contrast, lacks a defense capability. If you want to add more circuits, the MLO is an excellent addition to the MCB.


The allowable voltage capabilities of the circuits must be matched between the MCB and MLO. By doing this, circuit overload will be prevented. MLO is crucial if you wish to service many devices. It is best to talk to an electrician to decide what to use.


Considering the cost, if you want to replace the MLO, it will cost you between $400 and $1,000, depending on the amperage and circuit capacity. On the other hand, the cost for MCB will range from $10 to $100.

There can also be extra fees for labor and any necessary work permits.

When to Use MLO vs. MCB?


In some circumstances, MLO and MCB should be employed. You can utilize an MLO panel; however, it is only permitted to have two to six circuit breakers, unlike an MCB panel with as many circuit breakers as it can hold. There is an extra choice for secondary conductors to be protected by overcurrent protection on the primary side when the conductors do not exceed this length.

When can you Use a Main Lug Only panel?

You can use the main lug panel when you have an upstream breaker to safeguard the panel. However, you must utilize the main circuit breaker panel if you don’t have an upstream breaker.

Since there is no overcurrent protection device, it stands to reason that these boards are designated as “main leads only.” However, it can serve as the main breaker box if a primary breaker is typically installed to the main lug panel using a breaker set.

Mains Rating vs. MCB Rating

Because an MCB cannot be installed in a panel with bus bars that are rated for half the MCB rating. The maximum current that a circuit breaker may carry before tripping is determined by its ampere rating.

The rating range for standard tiny circuit breakers is 2 to 125 A. In residential applications, 20V branch circuits are protected by single-pole breakers, whereas double-pole breakers protect 240V branch circuits.

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What is the MLO on switchgear? 

MLO on switchgear is the sub-panel used after a main circuit breaker panel in the switchgear.

Why is MCCB called switchgear? 

MCCBs are called switchgear because they can be used to protect, handle and control electricity. MCCBs are called switchgear because they can be used to protect, manage and control electricity. 
Due to the incoming wires’ termination on the trip’s line side and direct connection to the bus, this panel lacks a main overcurrent protection device.

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