How to Wire a GFCI Circuit Breaker? 1, 2, 3 & 4 Poles GFCI Wiring (2022)

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

Table of Contents


  • 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 ELCBwhich is known asRCCB.

(Video) How To Install a Ground Fault Circuit Breaker to Replace a GFCI Outlet or Receptacle

ELCBstands 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).

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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.

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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.

(Video) Installing a GFCI Circuit Breaker

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.

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.

  • Related Post:How to wire a GFCI Outlet? – GFCI Wiring Circuit Diagrams

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.

(Video) How to wire a 50 Amp GFCI Breaker in a Sub Panel...(Part 2 of 4) DIY Spa Wiring made Easy.

  • Related Post:How to Wire GFCI Combo Switch and Outlet – GFCI Switch/Outlet Wiring Diagrams

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.

  • Related Post:Wiring of the Distribution Board with RCD (Residual Current Devices)

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.

(Video) Kitchen split receptacle GFCI upgrade - Siemens QF215A ClassA 2 pole GFCI circuit breaker

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.

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 maincircuit breakerto make sure the power supply is OFF before wiring a GFCI outlet.
  • Use the suitablevoltage and ampere rating of switchwithappropriate wire sizeandproper size MCBaccording 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.

Related Wiring Installation Diagrams and Tutorials:

  • Single-Phase Electrical Wiring installation in a Multi-Story Building
  • Three-Phase Electrical Wiring installation in a Multi-Story Building
  • How to Wire 120V Simultaneous Water Heater Thermostat?
  • How to Wire 240V Water Heater Thermostat – Non-Continuous?
  • How to Wire 3-Phase Simultaneous Water Heater Thermostat?


Four Poles GFCI GFCI Circuit Breaker MCB RCBO RCCB RCD Single Phase GFCI Single Phase RCD Wiring Single Pole GFCI Three Phase 4 Poles RCBO Circuit Breaker Three Phase 4 Poles RCD wiring Three Phase GFCI Three Poles GFCI Two Poles GFCI

(Video) How to Wire a GFCI Outlet - What's Line vs Load? - Electrical Wiring 101


How do you wire a 4 wire GFCI outlet? ›

The gfci is going to have one side that's marked line and one side that's marked load the load side

How is a GFCI circuit wired? ›

The line connection is used for all GFCI outlet installations. The circuit's hot wire (typically colored black or red) connects to the black or brass-colored screw terminal marked LINE. The white neutral wire connects to the silver-colored screw terminal marked LINE.

What wires go where on GFCI? ›

At the back of the GFCI are screw terminals marked “load” and “line.” The single screw at the bottom is the grounding screw. Attach both the black and white wires to the screw terminals on the line side. Fasten the black wire to the dark-colored screw and the white wire to the light-colored screw.

How do I wire a new GFCI outlet? ›

Your hot wire to the hot side and the neutral wire to the neutral. Side. But when it comes to

Can you wire a GFCI wrong? ›

If you miswired the GFCI it may not prevent personal injury or death due to a ground fault (electrical shock). If you mistakenly connect the LINE wires to the LOAD terminals, the GFCI will not reset and will not provide power to either the GFCI receptacle face or any receptacles fed from the GFCI.

How many wires do you need for a GFCI outlet? ›

The GFCI outlet consists of 2 sets of wires marked as 'line' and 'load'. The line set carries the incoming power and the load set distributes the power among additional outlets while also providing shock protection. Connect the power wire (black) to the line set and the white wire to the load set on the GFCI outlet.

Does power go to line or load on GFCI? ›

Fortunately, the confusion is quite simple to unwind: the “line” terminals are for power coming into your electrical box and the “load” terminals are for carrying that power plus GFCI protection to outlets further downstream.

What's the difference between GFCI and GFI? ›

Ground fault circuit interrupters (GFCI) and ground fault interrupters (GFI) are the exact same device under slightly different names. Though GFCI is more commonly used than GFI, the terms are interchangeable.

How do you wire a GFCI with 2 wires? ›

Install the GFCI

To connect the outlet, connect the black wire to the brass-colored LINE terminal, and tighten the screw securely. Connect the white wire to the silver-colored LINE terminal screw, and tighten it securely. Gently fold the wires and tuck them back into the box while pushing the outlet into place.

What is load and line on a GFCI? ›

The “line” wires are the incoming power from the breaker box and the “load” wires are the outgoing power that travels down the circuit to the next outlet.

How do you tell which wire is line and which is load? ›

Load Wire - Generally connected to the top half of your switch. If the wire is coming from the top of the switch box, it is likely your load wire. Line Wire - Generally connected to the bottom half of your switch. In some cases, line wires are marked with “line”, “pwr”, or a lightning bolt symbol.

How do you install a GFCI breaker? ›

Installing a GFCI Circuit Breaker - YouTube

Can you connect multiple GFCI outlets together? ›

Yes, you can daisy chain GFCI outlets together, but it's unnecessary and provides no added safety. There's nothing that says you can't install multiple GFCIs on the same circuit. However, there is no additional safety gained by doing so.

Can I connect two load lines to a GFCI receptacle? ›

It is common practice to attach two load lines using the back wire ports as long as they are the same wire size.

How does a 2 pole GFCI breaker work without a neutral? ›

Wire both hot conductors to the breaker and the breaker pigtail to the neutral bus. There will be no connection to the breaker neutral, so just ignore it. The way the breaker works is via "vector addition." It sums the current of the load and uses that as a reference as the current leaves one leg of the breaker.

What happens when you reverse line and load on a GFCI? ›

Line and Load Reversed at a GFCI - YouTube

What happens if hot and neutral are reversed? ›

One common issue with electrical outlets is reverse polarity, also known as "hot-neutral reversed." In this condition, the outlet has been wired incorrectly, altering the flow of electricity. While the outlet will still be able to provide power to your electrical items, it is also present a greater shock hazard.

What happens if you mix up line and load wires? ›

With simple on-off light switches, mixing up the line and load wires won't affect the operation. The power will be either off or on. It does become critical is when installing a GFCI outlet. Because it contains an internal circuit breaker, incorrect installation can cause a safety failure.

Will a GFCI trip without a ground? ›

A GFCI outlet will work without a ground wire and it's legal. Here's how to properly wire a GFCI outlet without the ground wire, and label it to meet code. If the outlet shorts out for any reason, it will still trip for safety, even without ground.

How many receptacles can be on a 20 amp circuit? ›

The answer to the question how many outlets on a 20 amp circuit is ten outlets. Always comply with the 80% circuit and breaker load rule, allowing a maximum load of 1.5 amps per receptacle. Remember that your circuit, wire sizes, and outlets must be compatible to avoid overheating and electrical hazards.

Can you wire a GFCI with 3 wires? ›

DO NOT install the GFCI receptacle in an electrical box containing (a) more than four (4) wires (not including the grounding wires) or (b) cables with more than two (2) wires (not including the grounding wire)." As you can see from the photos, I have 3 cables going into the box. All 3 cables have black/white/ground.

Why does my outlet have 4 wires? ›

What It Means When There Are 4 Wires In Your Outlet. Having more than two wires in an outlet simply means multiple outlets are using the same electric circuit and this outlet is a middle-of-run electrical outlet.

How do I wire a GFCI outlet with two hot wires? ›

How to Wire a GFCI Outlet - 2 wires to GFCI - YouTube

Will a GFCI work without a ground wire? ›

In short, yes. If your circuit doesn't have a ground wire, you can still install a GFCI outlet for protection. GFCI outlets without a ground wire are legal and work; however, choosing to install GFCI outlets without a ground wire does come with some disadvantages.

What is the difference between line and load on a GFCI? ›

There are two types of wires attached to the receptacle. The “line” wires are the incoming power from the breaker box and the “load” wires are the outgoing power that travels down the circuit to the next outlet.


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