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How to Wire a GFCI Circuit Breaker? 1, 2, 3 & 4 Poles GFCIs Wiring

Single Phase and Three Phase RCD and GFCI Wiring Circuit Diagrams and Installation


  • GFCI is the abbreviation of “Ground Fault Circuit Interrupter


  • RCD is the short form of “Residual Current Device
  • RCCB is also known as “Residual Current Circuit Breaker“.

GFCI and RCD or RCCB are same.

In America, it is commonly known as GFCIGround Fault Circuit Interrupter” or “GFIGround Fault Interrupter” or ALCIAppliance Leakage Current Interrupter“.

In Europe and Australia, the same thing is known as RCD “Residual Current Interrupter” or RCCBResidual Current Circuit Breaker” or if overcurrent protection device such as MCB is used with combination of RCD i.e. RCD + MCB, then it is known as RCBOResidual Current Circuit Breaker with Overcurrent Protection“. They are also known as safety switches. RCD may be defined as Current Operated ELCB which is known as RCCB.

ELCB stands for “Earth Leakage Circuit Breaker” and it has been replaced with the latest RCD device due to some of ELCB disadvantages (as it works on proper earth connection).

GFCIs and RCDs are used to protect against electric shock in case of ground faults and leakage currents and trip the circuit. According to IEC and NEC, it is must to use and install these devices in watery areas like laundry, kitchen, spa, bathroom and other outdoor installation.

Now, you have got the idea as we are going to show different wiring circuit diagrams for single pole, two poles, three poles and four poles (both single phase and three phase) RCD (RCCB) or GFCI circuit breakers.

Keep in mind that the the difference between single pole and two poles normal circuit breakers and a GFCI is that there is a builtin white wire on the back side of GFCI and it must be connected to the neutral busbar in the mains supply or it will not work and protect the circuit properly. Additional, you may read the difference between GFCI and AFCI in the previous post.

Difference between 1 & 2 Poles MCB and GFCI Breaker Terminals & Wiring

Wiring a Single Pole GFCI Circuit Breaker

The following wiring shows an ordinary outlet has been wired and protected through single phase single pole GFCI circuit breaker.

The builtin white wire in the ground fault circuit interrupter circuit breaker should be directly connected to the incoming supply neutral bar in the home mains distribution board or it will not work otherwise.

The Line (Hot, Live or Phase) is directly connected to the GFCI input and the output is connected to the line terminal of ordinary outlet / receptacle. The GFCI breaker load neutral has been connected to the load terminal of outlet. The ground terminal of outlet is connected to the ground bar in the mains distribution board.

This way, this 15-16A, 120V outlet is GFCI protected by 20A GFCI breaker and it is recommended to use it in the watery areas like bathrooms, kitchen, spa and other outdoor applications.

How to wire a Single Pole GFCI Circuit Breaker

The same wiring can be done for 230V, 13A circuit using the correct wire size, proper circuit breaker rating and suitable rating of switches and outlets.

Wiring a Two Poles GFCI Circuit Breaker

The following wiring shows an ordinary outlet has been wired and protected through a double pole GFCI circuit breaker.

Same like above wiring diagram for 1-Pole GFCI CB, the builtin white wire on the back side of GFCI must be connected to the neutral bar in the main DB. The Input is connected to the hot wire from Main MCB. The two wires as output (hot and neutral) are connected to the line terminals of ordinary outlet.

This way, this 24 amp, 120V ordinary outlet is protected by the 30 amp GFCI circuit breaker.

In case of 230V and 240V, the same wiring diagram should be follow expect only one line (L1 or L2) should be connected as hot to the input terminal of GFCI.

How to wire a Two Pole GFCI Circuit Breaker

Wiring a Three Poles GFCI Circuit Breaker

The following wiring shows hot water tub spa or whirlpool spa has been wired and protected through a three pole GFCI circuit breaker.

As we know that in 240V, there is no need to connect the neutral, but in some cases the appliances should be connected to the neutral according to the needs provided by the manufactures and user manuals.

This is a 4 wire GFCI wiring diagram. As mentioned above, the builtin white wire has been connected to the neutral busbar in the main DB. Two Lines from main distribution board MCB as L1 and L2 (Single Phase 240V) has been connected to the input of GFCI.

As shown in the fig, the three output terminals has been connected to the SPA control box followed by the printed marking i.e. the middle terminal is Neutral and the first and last one is two lines i.e. L1 and L2. At last, the ground wire from ground busbar has been connected to the ground terminal in SPA control box.

Wiring a Three Poles GFCI Circuit Breaker

Wiring a Four Poles RCBO or GFCI Circuit Breaker (Three Phase RCCB Wiring)

The three phase wiring for GFCI or RCD (RCCB) or RCBO wiring diagram shows the three lines (L1, L2 and L3) and neutral has been connected as input to the RCCB from Main board followed by MCB i.e. overcurrent protection.

The lower four terminals and ground wire of RCBO has been connected to the spa control box by the following sequence. Red (L1), Yellow (L2), Blue (L3), Black (Neutral) and Green/Yellow (Ground / Earth).

The following diagrams shows the three phase four poles RCBO (RCB + MCB) circuit breaker to control and protect hot water spa.

Wiring a Three Poles RCBO (MCB + RCB or RCD)Circuit Breaker

In case of three phase spa wiring, use 12 or 10 gauge wire size for each line. For example, use 12# or 4.0mm2 wire for up to 12kW, three phase 415V – 480V where the max current is 18.2A. Use 8# or 6.0mm2 wire for the same 12kW spa three phase 208V where the max current is 33.3 amp. In case of higher wattage, use the proper wire size according to the table and use manual.


  • Switch off the main circuit breaker to make sure the power supply is OFF before wiring a GFCI outlet.
  • Use the suitable voltage and ampere rating of switch with appropriate wire size and proper size MCB according to the load rating.
  • Use the correct polarity i.e. verify the Load and Line terminals while installing a GFCI for protection. In other words, connect the wires to the correct side of outlet for proper operation.
  • Regular maintenance, check and test is recommended while test the portable GFCI before each operation.
  • Contact the authorized and licensed electrician for GFCI installation if you are not sure about the wiring diagrams.
  • We have used Red for Hot or Line 1, Yellow for Line 2, Blue for Line 3, Black for Neutral and Green for Ground for illustration purpose only. Follow your own area wiring color codes according to NEC, IEC etc.
  • The author will not be liable for any losses, injuries, or damages from the display or use of this information or if you try any circuit in wrong format. So please! Be careful because it’s all about electricity and electricity is too dangerous.

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  1. I wants to know about types of earthing,,energy saving lights,safty divice,transformer safty and new incoming of electrical technology

    1. Why is a plug intended for 15 amps shown attached to a 30 amp breaker?

      I admit to doing something similar in mexico using a 240 volt 30 amp 2 pole breaker on a 15 amp circuit, only because it was available, but I wired in a 15 amp sub panel breaker so pump and wire was protected for amp overload while people were protected for current to ground.

  2. Notice: if you are not an electrician, leave this work to the professionals. The only way to make sure you and your family is safe is to have a valid licensed electrician perform these tasks. Thanks.

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