Ground Faults Done By : - Anas Atallah - Moatasem Tareq

Ground Faults : Ground faults by definition is the return of the current to ground by any path other than the neutral wire. Sometimes, it’s you !!

A ground fault is an inadvertent contact between an energized conductor and ground or equipment frame. The return path of the fault current is through the grounding system and any personnel or equipment that becomes part of that system. Ground faults are frequently the result of insulation breakdown.

It’s important to note that damp, wet, and dusty environments require extra diligence in design and maintenance. Since water is conductive it exposes degradation of insulation and increases the potential for hazards to develop.

L N Equipment Grounding Conductor (EGC) 6A Equipment Normal Circuit Operation The same amount of current flow from line to load and returns from load to line.

L N EGC Ground-Fault.06 A 12A 6A 5.94A Ground-Fault Ground – Fault (Indirect Contact)

When a person contacts the grounded enclosure of equipment with a fault to the enclosure it is called “indirect contact” The equipment grounding conductor (EGC) is effective Current divides and flows to ground based on the impedance of the two fault paths ▫EGC has low impedance … most of the fault current flows on it ▫person has comparatively higher impedance … small amount of fault current flows through the person (may or may not “feel a shock”)

L N Ground-Fault.1 A 6A 5.9A Ground – Fault (Direct Contact)

If ECG is absent (cut off prong on plug) then ALL the fault current will flow through the person. This is called direct contact. Amount of current determined by impedance of the person Dry hands or large person has higher impedance than wet hands or small person

Ground Fault Circuit Interrupter (GFCI) A ground fault circuit interrupter (GFCI) is a device that shuts off an electric power circuit when it detects that current is flowing along an unintended path, such as through water or a person.

Electric Shock Prevention System : Insulation ▫Deteriorates with age ▫accidentally or deliberately circumvented Equipment Grounding ▫deteriorates if not maintained ▫accidentally or deliberately circumvented GFCI ▫solves shortcomings of above systems ▫newest part of the protection system ▫does not depend on other elements of the system

Load IIn IOut If the current out = current back, the differential current transformer shows no output. L N The Current “Adding Machine” Differential Current Transformer

Current “Adding Machine” Under Ground Fault Conditions Load IIn = 6A IOut = 5.9A Ground-Fault.1A L N Differential Current Transformer If I-out does not equal I-in, the differential current transformer creates an output signal.

GFCIs are available in two types for permanent installation: GFCI circuit breakers. GFCI receptacles

GFCI vs AFCI circuit breakers

GFCI receptacles The receptacle type can be installed in a normal electrical outlet box.

Test and reset buttons verify proper functioning of the GFCI Test button will initiate end-of-life indication or power denial if product is no longer operational Push-to-test Button Test and Reset Buttons (Receptacle) Reset Button

Frequency of tests : Before first use After repair and before placing back in service Before use after suspected damage Every three months—however, cord sets and receptacles exposed to damage must be tested at regular intervals not to exceed six months

Electrocutions Associated With Consumer Products

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