GFCI Breaker Symbol
Definition: The GFCI Breaker symbol represents a combination circuit breaker and ground-fault current interrupter installed in a load-center panel that simultaneously provides overcurrent protection (thermal-magnetic trip) and personnel-protection ground-fault sensing (5 mA trip at ≤25 ms), as standardised by UL 489 and UL 943 Class A and required by NFPA 70 (NEC) for specific circuit types.
Also known as: GFCI circuit breaker, GFI breaker, ground fault breaker, GFCI CB, RCD breaker, RCBO (IEC equivalent).
What the GFCI Breaker symbol means
The GFCI Breaker symbol denotes a single or double-pole breaker that incorporates a differential current transformer in addition to the standard bimetallic-strip and magnetic-trip mechanism of a conventional circuit breaker. It connects to both the Line (panel bus) and Load (branch circuit conductors) terminals, and includes a pigtail Neutral wire that must land on the panel neutral bar so the device can measure neutral current independently.
Unlike a GFCI outlet, which protects only the devices plugged into it and any downstream LOAD-connected outlets, a GFCI Breaker protects every outlet and fixture on the entire branch circuit from the panel outward. This makes GFCI breakers the preferred choice for protecting circuits with multiple outlets spread over a large area, such as a garage workshop or outdoor kitchen, as well as for protecting circuits that feed appliances with no standard outlet.
How to identify the GFCI Breaker symbol
The GFCI Breaker symbol is drawn as a standard single-pole or double-pole miniature circuit breaker (MCB) rectangle with the addition of a small coil or differential-transformer symbol inside the block and a TEST button indicator. In wiring diagrams it is annotated 'GFCI' next to the breaker rectangle. The symbol has two connection points: Line (top, connecting to the panel bus bar) and Load (bottom, connecting to the branch circuit), plus a separate pigtail conductor shown as a short lead returning to the neutral bar.
Function in a circuit
A GFCI Breaker performs two independent protective functions in the same device. Its thermal-magnetic element trips on sustained overloads (e.g., a 15 A breaker trips at 135% load within minutes) and on short circuits (instantaneous magnetic trip). Its ground-fault sensing element continuously measures the vector difference between Line and Load currents using a toroidal current transformer; when this difference reaches 5 mA — indicating current returning via a fault path such as a person — the electronic circuit fires a shunt-trip coil that opens the breaker contacts within 25 ms. A TEST button verifies the ground-fault sensing function by injecting a deliberate 5 mA imbalance.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60898 covers miniature circuit breakers and IEC 61009 covers residual-current circuit breakers with overcurrent protection (RCBOs), the IEC equivalent of GFCI breakers. IEC 60617 depicts the RCBO as a combined circuit-breaker and RCD block symbol. IEC Class A RCBOs trip at 30 mA residual current for domestic applications. |
|---|---|
| ANSI/IEEE 315 | In North America, GFCI breakers are listed under UL 489 (molded-case circuit breakers) and UL 943 (ground-fault circuit interrupters), Class A (5 mA). NFPA 70 (NEC) Article 210.8 and 230 mandate GFCI breaker use for specific circuits. The ANSI symbol is a standard breaker rectangle marked 'GFCI' with a pigtail neutral indicated. |
| Key difference | IEC RCBOs (IEC 61009) operate at a 30 mA residual-current trip threshold for general domestic use; North American GFCI breakers (UL 943 Class A) trip at the stricter 5 mA threshold. The panel pigtail neutral requirement is specific to North American GFCI breakers; IEC RCBOs connect the neutral conductor through the device. |
Terminals / pins
| Pin | Name |
|---|---|
| line | Line |
| load | Load |
Typical values
Voltage: 120 V (single-pole) or 240 V (double-pole) AC, 60 Hz. Current ratings: 15 A, 20 A, 30 A, 40 A, 50 A common. Trip threshold: 5 mA ground fault (UL 943 Class A), ≤25 ms trip time. Interrupting capacity: typically 10 kAIC at 120/240 V for residential panels.
Where the GFCI Breaker symbol is used
- Entire branch circuits in bathrooms, kitchens, garages, and outdoor areas when a single GFCI breaker is more practical than multiple GFCI outlets
- Unfinished basements and crawl space circuits where multiple standard outlets are spread over a large area
- Circuits feeding hard-wired appliances (dishwashers, garbage disposals, bathroom exhaust fans) that have no outlet for a GFCI device
- Pool, spa, and hot-tub circuits per NEC Article 680, which require both GFCI protection and specific wire routing
- Boat dock and marina branch circuits where entire feeder runs require personnel protection
- Renovation projects where updating all outlets to GFCI type is impractical — a single GFCI breaker protects the whole circuit
- EV charger branch circuits (Level 1 and Level 2) where NEC 625 requires GFCI protection for 240 V outlets in certain locations
Example
In a residential panel diagram for a garage workshop, a 20 A GFCI Breaker symbol is shown connected at its Line terminal to the 120 V bus bar and at its Load terminal to the branch circuit hot conductor feeding four standard duplex outlets. The pigtail neutral wire from the GFCI breaker connects to the neutral bar, and the branch circuit neutral also lands on the neutral bar. The wiring diagram shows no GFCI outlets in the garage — the single GFCI breaker in the panel protects all four outlets simultaneously.
Key facts
- A GFCI Breaker combines overcurrent protection (thermal-magnetic trip) and ground-fault personnel protection (5 mA, ≤25 ms trip) in a single panelboard device, listed under UL 489 and UL 943 Class A.
- The GFCI Breaker symbol has two main circuit terminals: Line (connects to panel bus bar) and Load (connects to branch circuit); it also requires a pigtail neutral conductor that connects to the panel neutral bar for current sensing.
- A GFCI Breaker protects every outlet and appliance on the entire branch circuit, whereas a GFCI outlet protects only itself and any outlets connected to its LOAD terminals.
- NFPA 70 (NEC) Article 210.8 permits a GFCI circuit breaker as an alternative to GFCI outlets for providing mandatory ground-fault protection on bathroom, kitchen, garage, and outdoor circuits.
- The IEC equivalent of a GFCI Breaker is an RCBO (Residual Current Circuit Breaker with Overcurrent protection) per IEC 61009, which trips at 30 mA for general domestic use versus the 5 mA North American threshold.
- GFCI Breakers are available in single-pole (120 V, 15 A or 20 A) and double-pole (240 V, up to 50 A) versions for protecting both 120 V and 240 V branch circuits.
- A GFCI Breaker has a TEST button on its face; monthly testing is recommended by NFPA and the manufacturer to verify the ground-fault sensing mechanism remains functional.
Diagrams that use this symbol
Frequently asked questions
What does the GFCI breaker symbol look like in a wiring diagram?
The GFCI Breaker symbol is a standard miniature circuit-breaker rectangle annotated with 'GFCI', a TEST button indicator, and a pigtail neutral wire shown as a short lead returning to the neutral bar. It has two main circuit connection points: Line (top, to panel bus) and Load (bottom, to branch circuit).
What is the difference between a GFCI breaker and a GFCI outlet?
A GFCI Breaker is installed in the main panel and protects every device on the entire branch circuit. A GFCI Outlet is installed at an individual receptacle location and protects only the outlet itself plus any standard outlets connected downstream to its LOAD terminals. Both trip at 5 mA under UL 943 Class A, but the breaker offers wider circuit coverage.
What does GFCI breaker mean?
GFCI Breaker stands for Ground Fault Circuit Interrupter Breaker — a combination protective device that provides both standard circuit-breaker overcurrent protection and ground-fault sensing that trips within 25 ms when a fault current of 5 mA or more is detected, protecting persons on the entire branch circuit from electrocution.
Why does a GFCI breaker have a pigtail wire?
The pigtail (short white wire) from a GFCI Breaker must connect to the panel neutral bar so the device can independently sense the neutral current through its built-in toroidal current transformer. Comparing this neutral current to the hot-wire current allows the breaker to detect any imbalance caused by a ground fault. Without the pigtail connected, the GFCI sensing circuit cannot function.
What standard governs the GFCI breaker?
North American GFCI Breakers are listed under UL 489 (Standard for Molded-Case Circuit Breakers) for overcurrent protection and UL 943 (Standard for Ground-Fault Circuit-Interrupters) Class A for personnel protection. NFPA 70 (NEC) Articles 210.8, 230, and 680 specify where GFCI breakers are required. The IEC equivalent standard is IEC 61009 for RCBOs.
What is the trip current of a GFCI breaker?
A Class A GFCI Breaker trips at a ground-fault current of 5 mA (0.005 A) with a response time of 25 milliseconds or less, per UL 943. This 5 mA threshold is chosen to be below the 10 mA average let-go threshold for adult humans. The overcurrent (circuit-breaker) trip is independent and is governed by the breaker's ampere rating per UL 489.
Can a GFCI breaker replace a GFCI outlet?
Yes. A GFCI Breaker in the panel provides equivalent personnel protection for all outlets on the circuit and is explicitly accepted by NEC Article 210.8 as an alternative to GFCI outlets. Installing a GFCI Breaker is often more economical when a circuit has many outlets, or when hard-wired appliances (with no outlet) need GFCI protection.
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