We only think about it when “the power trips”, yet the electrical panel is the most important safety equipment in the home. The circuit breaker protects cables and appliances, the residual current device (RCD) protects people against electrocution. Understanding their role helps you talk with your electrician, spot a dangerous installation and react correctly when the power cuts out.
Important: this article explains the basic principles. Any work inside an electrical panel must be carried out with the power off by a qualified electrician.
Contents
Circuit breaker and RCD: who does what?
| Device | Protects against | Key point |
|---|---|---|
| Main circuit breaker (supply breaker) | Overconsumption of the whole installation | At the head of the installation, linked to your supply contract; lets you cut everything |
| Branch circuit breaker (MCB) | Overloads and short circuits on one circuit | One per circuit; protects the cable against overheating |
| 30 mA residual current device | Current leaking to earth (risk of electrocution) | Protects people; covers a group of circuits |
| Residual current circuit breaker (RCBO) | Both at once | Practical for a separate circuit (outdoors, pool, workshop) |
The circuit breaker: it protects the cables
When too many appliances run on the same circuit, the current exceeds what the cable can handle and the cable heats up: this is an overload. When the live and neutral wires touch, the current rises suddenly: this is a short circuit. In both cases, the circuit breaker cuts the circuit before the cable is damaged or starts a fire.
The residual current device: it protects people
The RCD constantly compares the current going out with the current coming back. If part of the current “escapes” (through a faulty appliance, a damaged cable… or through a person), it cuts the power in a fraction of a second. A sensitivity of 30 mA is the one used to protect people. There are several types (AC for everyday uses, A for certain electronic appliances such as washing machines or hobs): your electrician will choose the right one for each group of circuits.
Ratings and cable cross-sections: the golden rule
The rating of a circuit breaker (in amps) must match the cross-section of the cable it protects. Commonly used indicative guidelines, to be confirmed by your electrician:
- Lighting: 10 A with 1.5 mm² cable;
- Sockets: 16 A or 20 A with 2.5 mm² cable;
- Dedicated circuits (water heater, washing machine, oven): one dedicated circuit each, often 20 A in 2.5 mm²;
- Hob: often 32 A with 6 mm² cable;
- Air conditioners: according to the power stated in the manufacturer's manual, on a dedicated circuit.
Brico MIM tip: if a circuit breaker trips often, never replace it with a higher rating “so that it holds”. You would remove the cable's protection, and the cable could then overheat inside the wall. Find the cause (faulty appliance, overloaded circuit) with an electrician.
Earthing, essential
The earth carries leakage currents into the ground instead of letting them pass through your body. Without it, the metal casing of an appliance (water heater, washing machine, refrigerator) can become live. The RCD and the earth work together: one does not replace the other. In wet rooms (bathroom, kitchen, laundry room), this protection is even more important. Have the value of your earth connection checked by a professional, especially in an older house.
Organising your electrical panel
- Spread the circuits over several RCDs: in the event of a fault, only part of the house is cut off (and not the refrigerator along with the lighting).
- Label each circuit breaker: you immediately identify the circuit concerned.
- Keep spare space for future additions (air conditioner, pump, outdoor lighting). To size it correctly, read our guide how to choose the number of modules for your electrical enclosure.
As for equipment, the Hager 24-module enclosure with transparent door lets you see which breaker has tripped without opening the panel, and the 47-module flush-mounted enclosure with breaker slot suits villas with many circuits. For an outdoor circuit (garden, pump, gate), choose an IP65 waterproof enclosure and waterproof electrical boxes for the connections. The full range is in the Electrical enclosures collection; prices are shown on each product page.
Warning signs not to ignore
- A circuit breaker or RCD that trips regularly;
- The RCD tripping when it rains (moisture in an outdoor box or light fitting);
- A socket or switch that is warm, blackened or crackling;
- A burning smell near the panel;
- Exposed wires, terminal blocks without a box, a panel without an RCD.
In all these cases, switch off the circuit concerned and call in a qualified electrician. And once a month, press the “Test” button on your RCDs: they should trip immediately. If they do not cut the power, have them replaced.
Frequently asked questions about circuit breakers and RCDs
My RCD trips and will not reset, what should I do?
Switch off all the circuit breakers it protects, reset the RCD, then switch the breakers back on one by one. The one that makes the RCD trip shows the faulty circuit: unplug the appliances on that circuit and call an electrician if the fault persists.
Can I replace a circuit breaker myself?
We advise against it without electrical skills. Even with the main breaker off, some parts of the panel may remain live. Leave this job to a professional.
Is an RCD enough without an earth connection?
No. The RCD is an additional protection: a safe installation needs a proper earth connection and suitable protective devices.
Do you deliver everywhere in Morocco?
Yes, Brico MIM delivers to every city in Morocco, with cash on delivery.
A clean, safe electrical panel
Flush-mounted, surface-mounted or waterproof electrical enclosures and junction boxes, delivered everywhere in Morocco.
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