Understanding Leakage Current & Its Risks in Medical Devices
Understanding Leakage Current & Its Risks in Medical Devices
TL;DR: Leakage current is the unintended flow of electricity from a medical device to a patient or caregiver. Even small currents can cause shocks, burns, or interference with life-support equipment. NFPA 99 and IEC 60601 standards set strict thresholds for allowable leakage current, and surveyors often cite facilities that fail to measure or document these tests.
What Is Leakage Current?
Leakage current refers to the electrical current that unintentionally escapes from a medical device’s normal circuit and flows through conductive surfaces, protective grounding, or even the patient’s body.
In patient care, leakage current is dangerous because:
Patients often have compromised health and may be more sensitive to shocks.
Invasive devices (catheters, ECG leads, ventilators) provide a direct electrical pathway.
Caregivers are also at risk when handling equipment.
This is why NFPA 99 Health Care Facilities Code and international standards like IEC 60601 require strict testing and limits.
Why Leakage Current Testing Matters
Surveyors and regulators expect facilities to test leakage current for all Patient Care-Related Electrical Equipment (PCREE). A device that passes a visual inspection can still fail leakage current thresholds.
Uncontrolled leakage current can lead to:
Micro-shocks: tiny electrical discharges that interfere with heart rhythms.
Burns or skin injuries: from current escaping through conductive surfaces.
Device malfunction: sensitive electronics can be disrupted.
Survey deficiencies: missing leakage current logs is one of the most common PCREE citations.
Accepted Leakage Current Thresholds
Per NFPA 99 and IEC 60601-1 standards:
Patient Care Devices (normal condition): ≤ 100 µA (microamps)
Patient Care Devices (single fault condition): ≤ 500 µA
Protective Earth Conductor: ≤ 500 µA
➡️ These thresholds are intentionally low because even microamp-level currents can disrupt cardiac function in vulnerable patients.
Common Causes of Leakage Current Failures
Surveyors frequently see:
Damaged Power Cords
Frayed cords or missing ground pins increase leakage risk.
Poor Grounding
Equipment plugged into outlets with bad or missing grounds can’t safely redirect current.
Aging Equipment
Older devices with degraded insulation or worn components leak more current.
Improper Modifications
“Workarounds” or field repairs can compromise electrical safety.
Case Examples
Example 1: A nursing home had multiple resident beds fail inspection because the ground prongs were missing from their plugs. Leakage current readings were over 400 µA, well above the allowable 100 µA threshold.
Example 2: A ventilator passed a visual check but failed leakage current testing. The device had deteriorated internal wiring, creating a risk of patient shock. Surveyors cited the facility for failure to test according to NFPA 99.
Best Practices for Controlling Leakage Current
Test Annually (or per NFPA 99 requirements):
Use a biomedical analyzer to measure leakage current under both normal and fault conditions.
Check Cords and Grounds First:
Replace damaged cords immediately.
Verify outlets are properly grounded.
Maintain Documentation:
Keep logs of test results, corrective actions, and technician signatures.
Surveyors expect this paperwork during inspections.
Train Staff:
Ensure only qualified biomedical personnel conduct leakage current testing.
Retire High-Risk Equipment:
If leakage current is repeatedly high, replace the device rather than patching it.
Key Takeaways
Leakage current is invisible but dangerous. Even small currents can harm patients.
Regulatory thresholds are strict — 100 µA in normal conditions for most devices.
Testing + documentation are essential. Surveyors cite facilities that skip or under-document leakage current checks.
Resources
NFPA 99 Health Care Facilities Code
IEC 60601-1 Standard Overview
FDA Medical Device Guidance
OSHA Healthcare Electrical Safety
Reviewed by the PCREE Test Compliance Team
Last Updated: September 2025