Type A vs Type B RCCB: Complete Comparison Guide for Modern Electrical Safety 2026

はじめに

RCBO（過電流ブレーカー）｜安心と信頼の光安製作所

Residual Current Circuit Breakers (RCCBs) are among the most important safety devices used in modern electrical installations. Their primary purpose is to protect people and property from electric shock, earth leakage faults, and fire hazards caused by insulation failures.

However, not all RCCBs are designed to detect the same type of leakage current. As electrical systems become increasingly dependent on power electronics, variable frequency drives (VFDs), EV chargers, solar inverters, and industrial automation equipment, choosing the correct RCCB type becomes critical.

Among the most commonly discussed options are タイプA RCCB そして タイプB RCCB. While both provide residual current protection, their detection capabilities differ significantly.

Choosing the wrong type may result in:

• Failure to detect dangerous leakage currents
• 迷惑なトリップ
• Reduced electrical safety
• Non-compliance with electrical standards
• Increased fire and equipment damage risks

In this guide, we will explain the differences between Type A and Type B RCCBs, their operating principles, applications, advantages, limitations, and selection criteria.

RCCBとは何か？

An RCCB (Residual Current Circuit Breaker) continuously monitors the current flowing through live and neutral conductors.

通常の状態では

Current entering = Current leaving

When an insulation fault or electric shock occurs:

Current entering ≠ Current leaving

The RCCB detects this imbalance and disconnects the circuit within milliseconds.

Main Functions

• 感電に対する保護
• Earth leakage protection
• 火災予防
• Additional protection for electrical installations

Unlike MCBs, RCCBs do not provide overload or short-circuit protection. Therefore, they are usually installed together with an MCB or integrated into an RCBO.

Understanding Residual Current Types

Before comparing Type A and Type B RCCBs, it is important to understand the different forms of residual current.

Modern electrical equipment can generate:

AC Residual Current

Traditional sinusoidal alternating current leakage.

Common sources:

• 照明回路
• Heating equipment
• 家電製品

Pulsating DC Residual Current

Leakage current containing a DC component superimposed on AC.

Common sources:

• 洗濯機
• Induction cookers
• LEDドライバー
• Variable-speed motor drives

Smooth DC Residual Current

Pure DC leakage current without AC characteristics.

Common sources:

• EV充電器
• ソーラー・インバータ
• 蓄電池システム
• Industrial frequency converters

Different RCCB types are designed to detect different combinations of these currents.

RCBO（過電流ブレーカー）｜安心と信頼の光安製作所

What Is a Type A RCCB?

動作原理

A Type A RCCB can detect:

✔ Sinusoidal AC residual currents

✔ Pulsating DC residual currents

It provides improved protection compared to the older Type AC RCCB.

Detectable Leakage Currents

Type A RCCB responds to:

• Pure AC residual current
• Half-wave rectified residual current
• Pulsating DC residual current

代表的なアプリケーション

Type A RCCBs are widely used in:

• 住宅
• 商業ビル
• Office installations
• Domestic appliances
• LED照明システム
• 洗濯機
• エアコン
• 電子電源

メリット

プロテクション強化

Detects both AC and pulsating DC leakage currents.

Affordable

Lower cost compared to Type B RCCBs.

Standard Choice for Modern Buildings

Suitable for most residential and commercial applications.

Widely Available

Easy replacement and maintenance.

制限事項

Type A RCCBs cannot reliably detect:

• スムーズな直流残留電流
• 高周波残留電流
• Leakage generated by advanced power electronics

In such applications, Type B RCCBs are required.

RCBO（過電流ブレーカー）｜安心と信頼の光安製作所

What Is a Type B RCCB?

動作原理

Type B RCCBs are the most advanced RCCB category.

彼らは検出できる：

✔ AC residual currents

✔ Pulsating DC residual currents

✔ Smooth DC residual currents

✔ Mixed-frequency leakage currents

✔ High-frequency residual currents

Detectable Leakage Currents

Type B RCCBs provide protection against:

• AC leakage current
• Pulsating DC leakage current
• Smooth DC leakage current
• Residual currents up to 1 kHz and beyond (depending on design)

代表的なアプリケーション

Type B RCCBs are commonly installed in:

• 電気自動車充電ステーション
• 太陽光発電システム
• 蓄電池システム
• UPS installations
• Industrial frequency converters
• 可変周波数ドライブ（VFD）
• CNC machines
• 医療機器
• データセンター

メリット

Maximum Protection

Provides the highest level of residual current detection.

将来を見据えたソリューション

Compatible with modern power electronics.

信頼性の向上

Reduces undetected leakage faults.

規制遵守

Required by many EV charging and renewable energy standards.

制限事項

より高いコスト

Type B RCCBs are significantly more expensive.

Larger Size

May require additional panel space.

より複雑な設置

Often requires specialist design considerations.

Type A vs Type B RCCB: Key Differences

Why Smooth DC Leakage Is Dangerous

Modern electronic equipment often uses rectifiers, inverters, and switching power supplies.

These devices can generate smooth DC leakage currents.

The Blinding Effect

A major problem occurs when smooth DC current reaches a standard RCCB.

The DC component can saturate the magnetic core of the sensing transformer.

As a result:

• Detection sensitivity decreases
• Fault currents may not be detected
• Protection becomes unreliable

This phenomenon is often called:

RCCB blinding

Type B RCCBs are specifically designed to prevent this issue.

Type A RCCB Applications

住宅設備

Most modern homes contain appliances generating pulsating DC currents.

例を挙げよう：

• 洗濯機
• Heat pumps
• Smart appliances
• LED lighting

Type A RCCBs are generally recommended for residential installations.

商業ビル

Suitable for:

• 事業所
• 小売店
• ホテル
• 学校

General Electronic Loads

Any application where pulsating DC leakage may occur but smooth DC leakage is unlikely.

Type B RCCB Applications

EV充電ステーション

Electric vehicle chargers use AC/DC conversion technology.

Smooth DC leakage can occur during charging.

Many international standards require Type B protection or equivalent DC monitoring.

太陽光発電システム

Solar inverters generate DC and AC components simultaneously.

Leakage currents may contain:

• スムーズDC
• 混合周波数
• Harmonics

Type B RCCBs provide comprehensive protection.

産業オートメーション

Industrial equipment often includes:

• 周波数コンバータ
• Servo drives
• Motor controllers

These devices frequently generate DC leakage currents.

Medical Facilities

Critical medical equipment demands reliable fault detection.

Type B RCCBs offer enhanced safety.

International Standards for Type A and Type B RCCBs

Several standards define RCCB performance requirements.

IEC 61008

Specifies requirements for RCCBs without integral overcurrent protection.

IEC 62423

Defines advanced residual current devices including:

• タイプF
• タイプB

IEC 60364

Provides installation guidance for low-voltage electrical systems.

EV Charging Standards

Many EV charging regulations reference:

• IEC 61851
• IEC 60364-7-722

These often require Type B RCCBs or equivalent DC fault monitoring.

How to Choose Between Type A and Type B RCCB

Choose Type A RCCB When:

✔ Residential applications

✔ Commercial buildings

✔ Standard electronic appliances

✔ Cost-sensitive projects

✔ No smooth DC leakage expected

Choose Type B RCCB When:

✔ EV charging stations

✔ Solar PV installations

✔ Battery storage systems

✔ Industrial automation

✔ Variable frequency drives

✔ Medical equipment

✔ Smooth DC leakage may occur

Common Installation Mistakes

Using Type AC Instead of Type A

Many installers still use outdated Type AC RCCBs.

This can leave electronic loads insufficiently protected.

Using Type A for EV Chargers

EV charging systems may generate smooth DC leakage currents.

A Type A RCCB alone may become ineffective.

Ignoring Manufacturer Recommendations

Equipment manufacturers often specify the required RCCB type.

Failure to follow recommendations may void warranties.

Incorrect Coordination

RCCBs should be coordinated with:

• MCB
• RCBO
• サージ保護装置

Proper selectivity improves system reliability.

Future Trends in Residual Current Protection

Electrical systems continue to evolve.

Key trends include:

Growth of Electric Vehicles

Millions of EV chargers are being installed worldwide.

Demand for Type B RCCBs continues to rise.

Expansion of Solar Energy

Residential and commercial solar installations require advanced protection.

Smart Buildings

Building automation systems increasingly rely on power electronics.

Energy Storage Systems

Battery technologies introduce additional DC leakage risks.

As a result, Type B RCCBs are becoming more common in modern electrical infrastructure.

よくある質問

Is Type B Better Than Type A?

必ずしもそうではない。.

Type B offers broader protection but is only necessary when smooth DC leakage currents may occur.

For standard residential installations, Type A is usually sufficient.

Can Type A Replace Type B?

そうだ。.

If smooth DC leakage is possible, Type A cannot provide the required protection.

Is Type B RCCB Mandatory for EV Chargers?

In many installations, yes.

Local regulations and charger specifications should always be checked.

Why Is Type B More Expensive?

Type B RCCBs require advanced sensing technology capable of detecting multiple residual current waveforms and frequencies.

Can I Use Type B Everywhere?

Yes, technically.

However, the additional cost is often unnecessary for ordinary residential circuits.

結論

Understanding the differences between Type A and Type B RCCBs is essential for designing safe and compliant electrical systems.

Type A RCCBs are ideal for most residential and commercial applications, providing protection against AC and pulsating DC leakage currents. They offer an excellent balance between safety and cost.

Type B RCCBs deliver the highest level of protection by detecting AC, pulsating DC, smooth DC, and high-frequency residual currents. They are indispensable for EV charging stations, solar power systems, industrial automation, and other advanced electrical installations.

As renewable energy, electric vehicles, and power electronics become increasingly common, selecting the correct RCCB type is more important than ever. Investing in the right protection device ensures electrical safety, regulatory compliance, equipment reliability, and long-term system performance.