Type A RCDs have now become the standard choice for almost all new domestic and commercial installations. The days of relying on Type AC devices are effectively over - not because they were unsafe, but because modern appliances and electronics create leakage currents that Type AC simply cannot detect reliably.
Quick Answer: Type A RCDs detect both AC and pulsating DC earth leakage, making them suitable for virtually all modern circuits containing electronics. Type AC RCDs only detect pure AC leakage and can fail to trip when DC or electronic loads are present - which is now the norm in homes, EV chargers, appliances and inverter-based systems.
You can view all available models here: Type A RCDs.
This guide explains why Type A has replaced Type AC, what the 18th Edition says, and which circuits absolutely require Type A protection today.
Jump to:
Why Type AC RCDs Are No Longer Suitable
Type AC RCDs were originally designed for purely resistive or inductive AC loads - lighting, heating, simple appliances, etc. Those loads were predictable and produced clean, sinusoidal leakage currents.
Modern circuits are nothing like that.
Almost every home now includes electronics that generate:
- Pulsating DC leakage
- Half-wave rectified currents
- Electronic switching noise
- Distorted AC waveforms
Type AC RCDs cannot detect this leakage reliably, meaning they can delay tripping - or fail to trip entirely - under the wrong conditions.
What Type A RCDs Detect (and Why It Matters)
A Type A RCD detects:
- AC earth leakage
- Pulsating DC leakage
- Half-wave rectified DC leakage
- Leakage from electronic switching devices
These leakage types are generated by almost every modern device, including:
- EV chargers
- Washing machines
- Dishwashers
- Heat pumps
- Induction hobs
- Boilers with electronic controls
- LED lighting drivers
- Televisions, PCs and IT equipment
If you’re protecting a circuit with electronics - which is nearly every domestic and commercial circuit today - Type A is the correct choice.
You can explore all Type A devices here: Type A RCDs
Which Circuits Require Type A RCDs?
Under the 18th Edition and common manufacturer guidelines, the following circuits must use Type A protection:
- EV chargers - all modern chargers generate DC leakage
- Heat pumps - inverter-driven compressors
- Induction hobs
- Washing machines and dryers
- Dishwashers
- Boilers with electronic controls
- LED lighting circuits with drivers
- Any circuit feeding electronic appliances
Type AC is now only suited to very basic, purely resistive AC loads - which are increasingly rare.
What the 18th Edition Says About Type A RCDs
The 18th Edition does not ban Type AC devices outright - but it strongly recommends Type A for circuits supplying loads with electronic components.
Regulation note: Guidance documents and manufacturer instructions now collectively push installers toward Type A as the minimum standard. Amendment 2 reinforced this shift by aligning protection requirements with the reality of modern electronic loads.
Recommended Type A RCDs
These Type A RCDs are popular for domestic and commercial upgrades due to strong immunity to electrical noise and stable tripping characteristics.
- 2-Pole Type A High Immunity RCD – 100A
- 2-Pole Type A High Immunity RCD – 63A
- 2-Pole Type A High Immunity RCD – 80A
Browse the full category: Type A RCDs
FAQs
Installers frequently ask these when upgrading older boards.
Is Type AC now banned?
No - but it’s unsuitable for most modern loads and rarely recommended by manufacturers.
Do all circuits now need Type A?
Any circuit with electronics, switching devices or rectifier loads should use Type A protection.
Is Type A the same as Type B?
No - Type B handles smooth DC and EV/PV inverter leakage. Type A is the minimum for modern domestic loads.
Do High-Immunity RCDs replace the need for Type A?
No - immunity refers to noise resistance, not leakage detection type. High-Immunity Type A devices combine both benefits.
👉 Upgrading a board or wiring modern loads? Browse all Type A RCDs