Circuit breakers protect cables and equipment from overloads and short circuits. The three you will see in almost every panel in Bangladesh are the ACB, the MCCB and the MCB. They do the same basic job but at very different sizes. This guide explains the difference and how to choose.
MCB — Miniature Circuit Breaker
An MCB protects final circuits such as lights, sockets and small machines. MCBs are compact, DIN-rail mounted and usually rated up to about 63 A (some ranges go to 125 A). Their trip settings are fixed, set by the curve type (B, C or D).
MCCB — Molded Case Circuit Breaker
An MCCB is used for larger feeders and machines, commonly from about 16 A up to 1600 A. Many MCCBs have adjustable thermal and magnetic settings, and higher-end models have electronic trip units. MCCBs are the workhorse of MDBs, DBs and motor feeders.
ACB — Air Circuit Breaker
An ACB is used as the main incomer of an LT panel and for very large feeders, typically from about 630 A up to 6300 A. ACBs have electronic protection units with precise settings, high short-circuit ratings and are often draw-out type, so they can be removed safely for maintenance.
Comparison at a glance
| MCB | MCCB | ACB | |
|---|---|---|---|
| Typical rating | up to about 63–125 A | about 16–1600 A | about 630–6300 A |
| Trip settings | Fixed | Fixed or adjustable | Fully adjustable |
| Typical use | Lights, sockets | Feeders, motors, DBs | LT panel incomer |
| Mounting | DIN rail | Panel | Panel, often draw-out |
| Maintenance | Replace if faulty | Limited | Serviceable |
For high-voltage circuits above 1 kV, a vacuum circuit breaker (VCB) is used instead.
How to choose the right breaker
- Rated current: at or above the load current, and no higher than the cable can carry.
- Breaking capacity: higher than the prospective short-circuit current at that point.
- Number of poles: 1, 2, 3 or 4 poles depending on the circuit.
- Trip characteristics: suited to the load (motors need breakers that ride through starting current).
- Coordination: settings that let downstream breakers trip first.
Buying genuine breakers in Bangladesh
Counterfeit breakers look real but may not trip when needed — a serious fire risk. To stay safe:
- buy from an authorised partner or a reliable supplier
- check the packaging, labels, serial numbers and weight against the manufacturer’s information
- be cautious when a price is far below the market
- keep invoices for warranty and compliance audits
Unique Quality Engineering has supplied electrical components since 2012 and is a business partner of ABB, Schneider Electric, Mitsubishi, Siemens and Fuji Electric. We supply genuine spare parts for all kinds of panels.
Frequently asked questions
Can I replace an MCCB with a different brand?
Yes, if the rating, breaking capacity and dimensions suit the panel. Our engineers can recommend an equivalent.
Do you stock contactors, relays and meters too?
Yes. We supply contactors, overload relays, timers, meters and other switchgear components.
Get breaker prices
Send us the brand, model or rating and quantity you need. Request a quotation and we will reply with availability and price.
বাংলায় পড়ুন: এসিবি, এমসিসিবি ও এমসিবির পার্থক্য: সঠিক সার্কিট ব্রেকার বাছাই ও আসল ব্রেকার চেনার উপায়
