Miniature circuit breakers (MCBs) and moulded case circuit breakers (MCCBs) both protect a circuit against overload and short circuit, and both can be switched off by hand. They differ in size, current range, breaking capacity and how much of the trip behaviour you can adjust.
Quick comparison
| MCB | MCCB | |
|---|---|---|
| Typical current range | Low, up to about 125 A | Higher, from tens of amps to well over 1,000 A |
| Breaking capacity | Lower (a few kA to about 10-15 kA) | Higher (tens of kA, depending on the model) |
| Trip settings | Fixed in most models | Often adjustable (thermal and magnetic, or electronic) |
| Typical place | Final circuits, lighting and socket distribution boards | Main and sub-main feeders, motor feeders, larger loads |
| Size and cost | Small, lower cost | Larger, higher cost |
Exact ratings vary by manufacturer and series; always read the datasheet of the specific device.
When an MCB is the right choice
- Final circuits in distribution boards (lighting, sockets, small equipment).
- Loads well within the breaker's rated current and the fault level at that point.
- Where fixed, standard trip curves (B, C or D) are enough.
When you need an MCCB
- Incoming and outgoing feeders of a main or sub-main distribution board.
- Higher currents, or a higher prospective short-circuit current than an MCB can interrupt.
- Where you need adjustable settings to coordinate (discriminate) with upstream and downstream devices.
- Where accessories such as shunt trips, auxiliary contacts or motor operators are required.
Checklist before you specify a breaker
- Rated current of the load and the cable it protects.
- Prospective short-circuit current (kA) at the installation point.
- Number of poles and system voltage.
- Trip curve or adjustable range, and coordination with other devices.
- Applicable standard and project documentation requirements.
- Space available in the enclosure or panel.
Related reading and services
- Motor Control Centre (MCC): parts, types and how to choose
- Soft starter vs VFD: how to choose
- LV Protection & Distribution
- Electrical Panel Assemblies
Need help selecting breakers for a project in Saudi Arabia? Contact Arab Arc Trading with your load list and fault level and we will advise on the options.
