A residual current device, or RCD, is a life-saving tool intended to shield you from a lethal electric shock if you accidentally contact something live, such as a bare wire. Additionally, it may offer some protection against electrical fires. RCDs give a level of personal protection that is not possible with standard fuses and circuit breakers.
What does an RCD do?
An RCD is a delicate safety mechanism that, in the event of a fault, turns off the power immediately.
An RCD is made to guard against the dangers of fire and electrocution brought on by earth faults. For instance, if you accidentally touched live wires after accidentally cutting through the cable while mowing the grass or if malfunctioning equipment overheats and sends an electrical current to earth.
Selection of Types of RCDs
RCDs come in a variety of shapes and behave differently when DC components or other frequencies are present.
The following RCDs are offered with the corresponding symbols, and the designer or installer must choose the ideal model for the given application.
RCD Types
- Type AC – General purpose use, RCD can detect & respond to AC sinusoidal wave only.
- Type A – Equipment incorporating electronic components RCD can detect & respond as for type AC, PLUS pulsating DC components.
- Type F – Equipment with frequency-controlled speed drives RCD can detect & respond as for type A, PLUS high-frequency residual current.
- Type B – Electric vehicle chargers, PV supplies.
RCD can detect & respond for type F, PLUS smooth DC residual current.
RCDs & Their Loads
| RCD | Types of Load |
| Type AC | Resistive, capacitive, inductive loads
Immersion heater, oven / hob with resistive heating elements, electric shower, tungsten / halogen lighting |
| Type A | Single phase with electronic components
Single phase inverters, class 1 IT & multimedia equipment, power supplies for class 2 equipment, appliances such as washing machines, lighting controls, induction hobs & EV charging |
| Type F | Frequency controlled equipment
Appliances containing synchronous motors, some class 1 power tools, some air conditioning controllers using variable frequency speed drives |
| Type B | Three phase electronic equipment
Inverters for speed control, ups, EV charging where DC fault current is >6mA, PV |
Kempston Controls is committed to finding you the ideal solution for your application. Call us today on 042 9359393, email us at electrical@kempstoncontrols.ie, or alternatively contact us here, we will be happy to help.
