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How to Wire a Two-Pole GFCI Breaker in a 120/240V Panel

Electrical Technology
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How to Install a 2-P, 20A – 240V GFCI Breaker for Branch Circuits

2-Pole GFCI Breaker

A two-pole GFCI (Ground-Fault Circuit Interrupter) breaker is used to provide both overcurrent protection and ground-fault protection for 240V loads or 120/240V multi-wire branch circuits (MWBCs). Typical applications include electric water heaters, hot tubs, spas, HVAC equipment, pool pumps, and certain receptacle circuits in wet or outdoor locations as per NEC requirement.

Unlike standard 2-pole breakers, a 2-pole GFCI breaker continuously monitors the current balance between ungrounded (hot) conductors and the neutral conductor. If an imbalance exceeding 5 mA is detected, it indicates there is a current leakage to ground, therefore, the GFI breaker trips instantly to reduce the risk of electric shock.

A GFCI breaker differs from a standard breaker. It protects 240V circuits (two 120V hot conductors supplied from both Hot 1 or Hot 2) and offer protection against both overcurrent and ground faults.

A 2-P GFCI requires a neutral connection to the breaker, that’s why it has a built-in white pigtail wire which connects to the neutral busbar in the main panel. In case of 120/240V circuits (such as NEMA 14 series e.g. NEMA 14-50), the load side neutral is connected to the GFCI, not to the neutral busbar in the main panel. If load side neutral doesn’t required in a 240V circuit (such as NEMA 6-20 receptacle), only the white pigtail connects to the neutral busbar. This way, a GFCI protects the entire branch circuit, not just individual receptacles. In short, a GFCI provides both overcurrent and ground-fault protection.

A 2-P GFCI breaker requires a neutral connection to operate properly. For this reason, it is equipped with a built-in white pigtail conductor, which must be connected to the neutral busbar in the main panel.

In 120/240V circuits (such as those supplying NEMA 14-series receptacles (e.g., NEMA 14-50), the load-side neutral conductor must be terminated on the GFCI breaker’s neutral terminal, not on the panel’s neutral busbar. This allows the GFCI to monitor the current balance between the ungrounded (hot) conductors and the neutral conductor.

For 240V circuits that do not require a neutral (such as those supplying a NEMA 6-20 receptacle) the only neutral connection is the white pigtail from the GFCI breaker to the neutral busbar. No load-side neutral conductor is used in this case.

With this wiring method, the GFCI breaker provides ground-fault protection for the entire branch circuit rather than for individual receptacles only. In short, a GFCI breaker provides both overcurrent protection (as a circuit breaker) and ground-fault protection for personnel.

Characteristics:

  • Number of Poles: 2-pole – connects to two lines (L1 & L2), i.e. both hot conductor (black and red). Both lines are mechanically and electrically linked together.
  • Voltage: Operates on and protects 240V branch circuits. (Line-to-Line).
  • Amperage Rating: Commonly available in 15A, 20A, 25A and 30A.
  • Wiring: Two hot conductors from the breaker, a ground wire (+ a neutral if required) from ground/neutral busbar connects to the branch circuit in a 240V supply. The built-in white pigtail on the GFCI breaker always connects to the neutral busbar in the main panel.
  • Operation: Trips when there is an overload, short circuit, or ground-fault on a single or both hot conductor(s).
  • Application: Used as per NEC requirement for standard lighting, outlets, receptacles, sockets and small to medium load appliances located in outdoor or wet areas.

NEC Requirements for GFCI

NEC 210.8(A) requires ground-fault circuit-interrupter (GFCI) protection for 125-volt through 250-volt, single-phase, 15- and 20-ampere receptacles installed in specific locations. These locations include, but are not limited to, bathrooms, garages, outdoor areas, basements, kitchens, laundry areas, and similar spaces as identified by the Code.

In accordance with NEC 210.8(A), both dwelling and non-dwelling units must provide GFCI protection for all 120/240-volt outlets and receptacles installed in the locations listed in 210.8(A)(1) through 210.8(A)(11). This requirement applies to single-phase branch circuits rated 150 volts or less to ground.

Additionally, GFCI protection is required for various occupancies and equipment as specified throughout the NEC. Relevant Code sections include, but are not limited to, Articles 210.8, 406.3, 424.44, 426.28, 427.22, 511.12, 517.17, 517.20, 525.23, 530.44, 547.28, 555.35, 620.6, 625.54, 680.5, 680.21, 680.22, 680.23, 680.27, 680.32, 680.43, 680.44, 680.51 through 680.59, 680.62, and 680.71.

Wiring a Two-Pole GFCI Breaker in a 120/240V Panel

To install or replace a 2-P GFCI breaker in a 120/240V single-phase panelboard, follow the following simple steps.

Step 1: De-Energize the Panel: Switch off the main disconnect or main breaker and verify the absence of voltage using a non-contact tester.

Warning: Never touch the service entrance conductors or main breaker lugs as they remain energized even when the main breaker is OFF.

Step 2: Install the Breaker: GFCI breakers are manufacturer-specific such as Square D – Q/Homeline or BR/CH etc. Ensure the breaker is listed and approved for the panelboard model. When sure, snap the breaker onto both bus bars so that it engages L1 and L2.

Step 3: Connect the wires as follow:

  • Hot 1 (L1) as black wire to the breaker terminal 1
  • Hot (L2) as red wire to the breaker terminal 2
  • Load Neutral as white wire to the Neutral terminal on the GFCI breaker (if present)
  • Breaker white coiled pigtail to the neutral busbar in the panel
  • Equipment ground (EGC) as green or bare copper conductor to the ground busbar in the panel

Good to Know:

Step 4: Test and Reset: Replace the panel cover and restore the power. To test and inspect;

  • Press the TEST button on the GFCI breaker. The breaker must trip immediately.
  • Reset the breaker and verify proper operation of the load.

A 2-Pole GFCI breaker can be installed on a 120/240V AC single-phase, 3-Wire system, the 120/240V AC portion of a 240/120V, 3-Phase, 4-Wire system (High Leg), or on a 208Y/120V, 3-phase, 4-Wire system.

For a 2-Pole GFCI breaker, a load neutral is not required on 240V circuits. However, the white line neutral (pigtail) must be connected to the panel neutral for the device to function properly.

For 120/240V circuits where Neutral is required, the load neutral should be connected from the neutral terminal of GFCI, not from the neutral busbar.

Wiring 240V, 2-Pole GFCI Breaker without Neutral

In the given wiring diagram, a 15A, 240V, two-pole GFCI breaker is installed to protect a 15A, 250V receptacle (NEMA 6-15R). In accordance with NEC Table 310.16, the suitable conductor size for a 15A branch circuit supplying a NEMA 6-15R receptacle is #14 AWG copper. The equipment grounding conductor (EGC) must also be #14 AWG, as specified in NEC Table 250.122.

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Wiring 2-P, 15A-240V GFCI Breaker
Wiring 2-P, 15A-240V GFCI Breaker

Wiring 120/240V, 2-Pole GFCI Breaker With Neutral

In the given wiring diagram, a 50A, 120/240V, two-pole GFCI breaker is wired to protect a 50A, 120/250V receptacle (NEMA 14-50R). As the circuits needs a neutral wire, hence, the load side neutral is connected from the neutral terminal of the GFCI, not the neutral busbar in the main panel.

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Wiring Industrial Grade & EV Rated NEMA 14-50 Receptacle with a 2P GFCI

Similarly, the following wiring diagram shows how to install a 40A, 2-Pole GFCI breaker in 120/240V spa panel for hot tub. As mentioned before, the load side white neutral wire from GFCI is not required for most 240V and 208V dedicated circuits. If needed as per circuit requirement, the load side neutral is connected from the GFCI neutral terminal. Meanwhile, the built-in white pigtail must be connected to the neutral busbar in the main panel.

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Wiring 40A - 240V, 2-Pole GFCI Breaker for Hot Tub

Moreover, the following wiring diagram illustrates the installation of a spa panel box containing a 50A, 120/240V, two-pole GFCI breaker. The spa panel is supplied downstream from a standard 50A, two-pole breaker installed in the main 120/240V panel.

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Wiring 50A - 120/240V Spa Panel using 2-P GFCI & Breaker

Except for the 20A example shown, a 2-pole GFCI breaker may be installed for other circuit ratings and may supply various NEMA receptacles used on 240V or 120/240V single-phase systems as as:

Good to Know:

  • The voltage between L1 and L2 i.e. two Hots e.g. Hot 1 and Hot 2 = 240V phase to phase.
  • For 240V load without Neutral, the Neutral terminal (if present) from the breaker is unused (such as NEMA 6-15. 6-20 receptacles).
  • For 120/240V load with Neutral, the Neutral terminal from the breaker is connected to the load neutral (not to the neutral busbar in the main panel) such as NEMA 14-30. 14-50 receptacles.

Instructions, Precautions & Codes

  • As per NEC Table – 310.16, Table – 210.24(1) and NEC 240.4(D)(4), the suitable wire size is 12 AWG copper (or #10 AWG aluminum) to use with a 20A outlet and protected by a 20/120V GFCI/Breaker.
  • As per NEC Table 250.122, use the same #12 AWG copper for ground (EGC) wire size.
  • The correct size of breaker is 2-pole, 20A circuit breaker or GFCI for a 20A-125V outlet – NEC 210.21(B)(2).
  • For a 2-pole, 20A GFCI circuit, you may use NM-B (Romex) for indoor and dry locations, UF-B for outdoor or underground runs, and THHN/THWN conductors when installed in conduit.
  • A two-pole 20A GFCI/breaker can be used for 16A continuous load (which lasts 3 or more hours) and maximum 20A non-continuous load – 210.19(A), 210.20(A), 215.2(A), 215.3, and 230.42(A).
  • A 2-pole, 20-amp breaker/GFCI at 240 volt can handle non-continuous load of 4,800 watts (20A × 240V). For continuous use, limit the load to about 3,840 watts (80% of 1,800W).
  • Do not use 20A outlet on 15A circuit breaker. If more than one receptacle on the same circuit, you may allowed to use 15A outlet on 20A circuit breaker. In other words, It is code to use 15A outlet on 20A breaker (NEC 210.21(B)(2)), but it is not allowed to use 20A outlet on 15A breaker.

Warning:

  • Make sure to disconnect the power supply by switching OFF the breaker in the main panel before doing any electrical work.
  • If you are unsure, contact a licensed electrician to do it according to the local area codes.
  • 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 electricity is too dangerous.

Resources:

Standard Breakers & GFCI Breakers Wiring Installations

Sizing Breakers, Wires, and Panels

General Outlets and GFCI/AFCI Receptacles Wiring

Switches Wiring

Finding the Number of Breakers/Outlets in a Circuit

Main Panels Wiring Tutorials

General Wiring Installation Tutorials:

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