GFCI Leakage Current

I = V / R_path

Quick answer

This calculator solves I_leakage = V / R_path for Leakage Current. With Voltage 12 V, Fault Path Resistance 0.47 kΩ, the result is 25.53 mA. It solves in 3 directions, so you can enter the values you have and get the one you need.

Calculator

Leakage Current (mA)
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Formula

I_leakage = V / R_path

Description

A Ground Fault Circuit Interrupter (GFCI/RCD) monitors the difference between line and neutral current. When this imbalance exceeds the trip threshold (typically 5 mA for personnel protection or 30 mA in some regions), the device disconnects power within 25-40 milliseconds. The leakage current through a ground fault path follows Ohm's law, depending on the voltage and the impedance of the fault path through the person or equipment to ground. Understanding leakage current helps verify that GFCI protection will activate in a fault scenario.

Variables

  • I — Leakage current through the fault path (A)
  • V — Voltage between live conductor and ground (V)
  • R — Total resistance of the ground fault path (Ω)

Practical Notes

GFCI trip thresholds: UL 943 requires 4-6 mA for Class A devices (US), IEC 61008 specifies 30 mA for Type AC RCDs (EU). Some equipment has inherent leakage current due to EMI filter Y-capacitors (typically 0.5-3 mA), which can cause nuisance tripping. For sensitive environments like bathrooms and kitchens, use 5 mA GFCI devices. Medical equipment may require even lower thresholds.

Symbols and units

Symbol Meaning Default unit Accepted units
I Leakage Current mA pA, nA, µA, mA, A, kA
V Voltage V pV, nV, µV, mV, V, kV
R Fault Path Resistance Ω mΩ, Ω, kΩ, MΩ

Step by step

  1. 1. What you know: Voltage 12 V, Fault Path Resistance 0.47 kΩ
  2. 2. The relation: I_leakage = V / R_path
  3. 3. Substitute: V = 12 V, R = 0.47 kΩ
  4. 4. Result: Leakage Current = 25.53 mA

Related quantities from the same inputs

  • P = V × I = 0.3064 W

Worked examples

Minimum range

Given: Voltage 0.33 V, Fault Path Resistance 1 Ω

Result: Leakage Current = 0.33 A

Low range

Given: Voltage 3.3 V, Fault Path Resistance 10 Ω

Result: Leakage Current = 0.33 A

Typical

Given: Voltage 12 V, Fault Path Resistance 0.47 kΩ

Result: Leakage Current = 25.53 mA

High range

Given: Voltage 0.23 kV, Fault Path Resistance 4.7 kΩ

Result: Leakage Current = 48.94 mA

Maximum range

Given: Voltage 2.3 kV, Fault Path Resistance 47 kΩ

Result: Leakage Current = 48.94 mA

Solving for each variable

Solve for Leakage Current

Voltage 0.33 V, Fault Path Resistance 1 Ω → 0.33 A

Solve for Voltage

Leakage Current 100 µA, Fault Path Resistance 1 Ω → 100 µV

Solve for Fault Path Resistance

Leakage Current 100 µA, Voltage 0.33 V → 3.3 kΩ

How Leakage Current changes with Voltage

Voltage (input) Leakage Current (result)
1.2 V 2.553 mA
3 V 6.383 mA
6 V 12.77 mA
9 V 19.15 mA
12 V 25.53 mA
18 V 38.3 mA
24 V 51.06 mA
48 V 102.1 mA
84 V 0.1787 A
120 V 0.2553 A

The same result in other units

Unit Value
µA 25530
mA 25.53
A 0.02553

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Frequently asked questions

How do you calculate GFCI Leakage Current?

Use I_leakage = V / R_path. With Voltage 12 V, Fault Path Resistance 0.47 kΩ, Leakage Current works out to 25.53 mA.

How do you calculate gfci leakage to ground?

Rearrange for Leakage Current: with Voltage 3.3 V, Fault Path Resistance 10 Ω, Leakage Current is 0.33 A.

What is the formula for GFCI Leakage Current?

The formula is I_leakage = V / R_path. A Ground Fault Circuit Interrupter (GFCI/RCD) monitors the difference between line and neutral current.

How do you find Voltage when you know the other values?

Rearrange for Voltage: with Leakage Current 100 µA, Fault Path Resistance 1 Ω, Voltage is 100 µV.

How do you find Fault Path Resistance when you know the other values?

Rearrange for Fault Path Resistance: with Leakage Current 100 µA, Voltage 0.33 V, Fault Path Resistance is 3.3 kΩ.

What units does GFCI Leakage Current use?

Leakage Current is shown in µA, mA, A. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

Related Concepts

All Safety / Protection formulas →
Fuse I²t Rating Touch Voltage / Body Current Hi-Pot Test Voltage MOV Surge Energy GFCI Leakage Current Circuit Breaker Fault Power Capacitor Safe-Discharge Time

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