Not sure whether you need an MCB, RCCB, contactor, MCCB, or SPD? This guide explains the function of each device and helps you choose the right one for your residential, commercial, or industrial application.
Five Devices, Five Different Jobs
When building or upgrading an electrical panel, buyers often ask: “Do I need an MCB or an RCCB? What about a contactor or an SPD?” The answer depends on what you are trying to protect. Each device has a specific job. Choosing the wrong one can leave your system unprotected or cause nuisance tripping.
Miniature Circuit Breaker (MCB) – For Overload and Short Circuit
An MCB protects circuits from overload (too many amps over time) and short circuit (a sudden surge). It does not protect against electric shock or ground faults. Use MCBs for lighting, socket outlets, and general power distribution. HX series MCBs are available from 0.5A to 63A, with B, C, or D curves, and breaking capacities from 4.5kA to 10kA.
Residual Current Circuit Breaker (RCCB) – For Ground Fault and Electric Shock
An RCCB detects when current leaks to earth – for example, through a person touching a live wire. It trips within 0.1 seconds to prevent electrocution. RCCBs do not protect against overload or short circuit, so they must be used together with an MCB. Choose sensitivity: 10mA for high-risk areas (bathrooms, pools), 30mA for general protection, or 100mA for fire prevention.
AC Contactor – For Switching Motors and Heavy Loads
A contactor is an electrically controlled switch used to start and stop motors, lighting banks, heaters, and other heavy loads. Unlike an MCB, a contactor is designed for frequent switching – thousands of operations. HC2 series contactors cover from 9A to 95A, with AC or DC coils, and can be combined with auxiliary contacts and interlocks.
Molded Case Circuit Breaker (MCCB) – For High Current Main Distribution
When your load exceeds 63A, you need an MCCB. HM3 series MCCBs are rated from 125A to 800A, with breaking capacities up to 85kA. They are used as main breakers in distribution panels, for large motors, and for industrial machinery. Many HM3 models have adjustable current settings, allowing you to fine-tune protection without changing the device.
Surge Protective Device (SPD) – For Lightning and Voltage Spikes
An SPD protects sensitive electronics – PLCs, drives, telecom equipment – from lightning strikes and switching surges. Without an SPD, a single surge can destroy thousands of dollars in equipment. HS series SPDs are available in Type 1+2 (for main panels with lightning protection) and Type 2 (for sub-distribution boards).
Which One Do You Need?
Start with your application: For a home distribution board, you need MCBs plus a main RCCB. For a motor starter, you need a contactor plus an overload relay. For a factory main panel, you need an MCCB plus SPDs. Still not sure? Send us a photo or description of your panel, and we will recommend the correct devices for your project.
