The letter is not a detail
Every RCD carries a type letter next to its 30 mA marking. The letter says what shape of leakage current the device can actually detect — and a leak it cannot detect is a leak it will not disconnect.
- Type AC detects sinusoidal AC leakage only.
- Type A also detects pulsating DC leakage — the kind produced by rectifiers in ordinary appliances.
- Type F adds mixed-frequency leakage from inverter-driven motors.
- Type B adds smooth (pure) DC leakage.
Each type includes everything the previous one does, so the list is a ladder: AC, then A, then F, then B.
Why type AC is effectively obsolete
Almost every modern appliance has a switch-mode power supply behind its plug, and those rectify the mains. The resulting leakage is no longer a clean sine wave, and a type AC device may sit there without tripping. For that reason type AC is no longer accepted for household circuits across most of Europe under HD 60364; type A is the minimum. In CIS practice type AC is still sold and still legal in older installations, but there is no good reason to buy one today — the price difference against type A is small.
Which appliances force a higher type
- Washing machines, dishwashers, induction hobs, most electronics — type A.
- Inverter air conditioners, heat pumps, variable-speed pumps — type F.
- EV chargers and PV inverters — type B, unless the charger itself states that it contains built-in 6 mA DC fault detection.
The price ladder follows the same order: type A costs a little more than AC, type F noticeably more, and type B several times more than A. Buy the type each circuit actually needs instead of upgrading the whole panel — one dedicated type B RCBO for the EV charger is far cheaper than a type B incomer covering the whole home.
What PlanMyPanel does
The generator builds the panel on type A — the standards' baseline — and never fits type AC. Type B appears only where it is unavoidable: an EV charger without its own DC fault detection, which also forces a type B incomer. If you tell the wizard that the charging station has built-in 6 mA DC protection, the whole panel stays on type A and the price drops sharply. Type F is offered as a note rather than fitted automatically: it is an appliance-maker recommendation, not a requirement, so upgrading a single circuit is your call.
The blinding effect
Smooth DC leakage does not just go undetected by a type A or AC device — it magnetically saturates the core of that device, so it stops detecting ordinary AC leakage too. A single DC-leaking appliance can therefore switch off the protection of everything else behind that RCD. This is why an upstream RCD must be at least as capable as anything downstream; selective (type S) RCDs covers the cascade rule in detail.