A circuit breaker protects wires from overheating. An RCD or GFCI protects people from electrocution. The two devices solve different problems and modern electrical codes require both. This guide covers what RCDs and GFCIs are, how they save lives, and what travelers should know about destinations with weaker safety infrastructure.
The problem they solve
A standard circuit breaker trips when current exceeds 15-20 amps for residential circuits. This is the "wires overheating" threshold. Above 15-20 A, copper wires inside walls start to overheat, insulation degrades, fire becomes a risk.
But a person being electrocuted doesn't draw 15-20 A. They draw much less. The threshold where electric current becomes dangerous to humans:
- 1 mA: barely perceptible tingle
- 5 mA: noticeable shock, painful
- 10 mA: muscle contractions, "can't let go" current
- 30 mA: significant risk of cardiac arrhythmia
- 100 mA: likely cardiac arrest within seconds
- 1,000 mA (1 A): severe burns and tissue damage
The deadly range (30 mA to 100 mA) is far below the circuit breaker's 15-20 A trip threshold. A person being electrocuted at 50 mA isn't protected by the circuit breaker at all; the breaker happily allows the current to continue.
RCDs and GFCIs detect at the 30 mA threshold, providing protection where it actually matters.
How they work
The detection method is elegant. In a normal electrical circuit:
- Current flows out of the wall through the live wire
- Current flows back to the wall through the neutral wire
- The two currents are equal by Kirchhoff's law
If a fault occurs (the live wire shorts to a person, or to wet insulation, or to ground through a faulty appliance), some current escapes the normal path. The current going out (through live) is now greater than the current coming back (through neutral) because some is leaking to ground.
The RCD/GFCI continuously compares live and neutral currents using a sensitive current transformer. When the imbalance exceeds 30 mA (typical sensitivity), the device immediately disconnects the circuit. The interruption takes 25-40 milliseconds, fast enough to prevent serious harm even if a person is in contact with the live wire.
After tripping, the device must be manually reset (via a button on the device itself) before power is restored.
Where they're required
European Union
EU member states require RCDs at the panel level on all circuits serving bathrooms, kitchens, outdoor outlets, and garages. Most new buildings since 2010 have RCDs protecting the entire installation (whole-house RCD).
Trip threshold: 30 mA for personal protection.
United Kingdom
The UK requires RCDs on all socket circuits in new installations since 2008. Older installations are being retrofitted but the transition is incomplete.
Australia and New Zealand
Required on all socket circuits in new installations since 1991. Wide adoption in older buildings too.
United States
GFCI outlets are required at specific locations rather than at the panel:
- Bathroom receptacles
- Kitchen counter receptacles
- Laundry receptacles
- Outdoor receptacles
- Garage receptacles
- Basement receptacles
- Wet bar areas
The US approach trades off panel-level coverage for outlet-level coverage. Both approaches achieve similar safety outcomes.
Other countries
Variable. Most modern building codes worldwide include some form of RCD/GFCI requirement, though implementation varies widely. Older buildings in any country may lack protection regardless of current code.
RCD/GFCI in older buildings
If you're in an older hotel, hostel, or accommodation without modern electrical infrastructure:
- The outlet you're using may not have RCD/GFCI protection
- A fault that would normally trigger protection might not be caught
- The risk is small but non-zero
For travel to destinations with documented older infrastructure (parts of India, older European cities, rural areas worldwide), a portable RCD adapter provides personal protection regardless of the building's wiring.
Portable RCD adapters
A portable RCD ("plug-in RCD" or "travel RCD") is a small device that plugs into a wall outlet and provides protected outputs. It contains the same circuit as a built-in RCD/GFCI but in a portable form.
Use cases:
- Hotel bathrooms (where built-in protection may not exist)
- Outdoor charging while camping or in poolside settings
- Kitchen prep in long-term rental accommodations
- Travel to destinations with older electrical infrastructure
Cost: $20-50 for a quality portable RCD. Brands include Belkin, Schneider Electric, and various country-specific manufacturers.
For most travel scenarios, a built-in RCD in the room handles the protection. The portable RCD is a backup for situations where you suspect the wiring is older or where you're handling water near electricity.
RCD/GFCI testing
Both built-in and portable RCDs have a test button (labeled "T" or "Test"). Pressing it simulates a fault, which should immediately trip the device. The reset button (labeled "R" or "Reset") restores power.
Testing should happen:
- Monthly for built-in RCDs (most homeowners forget this)
- Before each trip for portable RCDs
- After any electrical incident in the building
A device that doesn't trip when tested has failed and should be replaced immediately.
False trips and limitations
RCDs occasionally trip when they shouldn't:
- High-draw appliances (water heaters, electric ovens) starting up
- Older appliances with degraded insulation (older washing machines)
- Surge events from lightning or grid fluctuations
- Capacitive coupling in long cable runs
Most false trips are minor and the device resets without issue. Persistent false trips suggest a real problem (faulty appliance, degraded wiring) that needs investigation.
RCDs also don't protect against:
- Phase-to-neutral shorts (the breaker handles these)
- Hot-to-hot shocks in 240 V systems (rare but possible)
- Persistent low-current leakage below the trip threshold
The RCD/GFCI is one layer of protection among several. Building codes typically require all layers (breaker for over-current, earth/ground for fault current path, RCD for residual current detection).
What travelers should know
For destinations where electrical safety is a concern:
- Inspect outlets for visible damage before use
- Don't use bathroom outlets unless they're clearly modern and likely RCD-protected
- Carry a portable RCD adapter for sensitive use cases
- Avoid older buildings where electrical work appears amateur or non-standard
For most modern hotels and accommodations in developed countries, RCD/GFCI protection is built-in and you don't need to think about it. The protection is there even if you're not aware of it.
The bottom line
RCDs (European) and GFCIs (American) are the same device with different names. They detect tiny imbalances in electrical flow (typically 30 mA) and disconnect power within milliseconds. They're required by building codes in any location where water and electricity could meet.
Modern buildings have RCD/GFCI protection built in. Older buildings may not. A portable RCD adapter provides the same protection for travel to destinations with weaker infrastructure or for charging in water-adjacent locations.
The protection is one layer in a system that also includes grounding and over-current protection. Together they make modern electrical systems much safer than they were 50 years ago.