TINY OFF-GRID HOUSE OVER CURRENT PROTECTION DEVICE

Photo Courtesy Of Schneider Electric HomeLine Plug-On-Neutral

ALTERNATING CURRENT (AC) OVER CURRENT PROTECTION DEVICE Over current protection devices includes fuses, fusible links & circuit breakers. The most common residential type are circuit breakers.  To define the purpose of an over current protection device, such as a circuit breaker that you can find inside a main service panel (MSP), it maybe better to first understand what it is not responsible for.  The purpose of the circuit breaker is not to protect an appliance (Load) or the operator; but to protect the current carrying wire (Conductor) from over heating which can cause an electrical fire.

NOTE: A circuit breaker is designed to power a continuous load up to 80% of a circuit breaker capacity.

PLUG-ON NEUTRAL CIRCUIT BREAKERS The Tiny Off-Grid House will use AC “Plug-On Neutral Circuit Breakers” in the MSP. This will make installation easier and reduce labor time. The ability of Plug-On Neutral Circuit Breakers to perform dual functions is also an assett to achieve, or even exceed, National Electrical Code (NEC) standards.

CON’S OF PLUG-ON NEUTRAL CIRCUIT BREAKERS

• Cost

PRO’S OF PLUG-ON NEUTRAL CIRCUIT BREAKERS

• Easier installation

• No use of pigtails

• Cleaner, less congested, gutter space inside MSP

GROUND FAULT CIRCUIT BREAKER Where ever a Ground-Fault Circuit Interrupter (GFCI) “receptacle”, aka Residential Current Device (RCD) is required, the Tiny Off-Grid House will use AC Plug-On Neutrals GFCI with combined Arc-Fault Circuit Interrupter (AFCI) “circuit breakers”, located in the MSP, instead of installing multiple GFCI’s “receptacles” at each point-of-use.

A GFCI receptacle—not to be confused with a GFCI Circuit Breaker—provides protection against electrical shock where water is present by comparing the incoming and outgoing current.  If an imbalance in the currents are detected between the two, the GFCI can deactivate power within 1/40 of a second. The GFCI receptacle detects current that is taking an unintended path (Leakage current) back to the source where it originated.  Once detected, the GFCI deenergizes the current “protecting people and animal companions from potentially fatal electrical shock.” GFCI’s are designed to deenergize current between 4 milliamps (.004) to 6 milliamps (.006).  Only less than 10 milliamps (.010) at a minimum of 2 seconds can be potentially fatal to an adult size human. According to the Occupational Safety & Health Administration (OSHA) “currents that are greater than 75 mA can cause your heart to shift its regular beating pattern.”  This condition is called Ventricular Fibrillation (V-Fib) exhibited by an uncontrolled rapid twitching of the heart muscle that prevents perfusion of the blood through the heart arteries and ventricules. 

A ground fault can occur when a hot wire (energized conductor) comes in contact with an ungrounded conductor or equipment metal frame. A human being, comprised of 60% water, is a good conductor of electricity  and will complete the circuit to ground.  Subsequently, most GFCI’s are installed in moist or wet locations such as in: bathrooms (NEC 210.8 (A)(9), kitchens (NEC 210.8 (A)(6)) laundry rooms, water treatment compartment (NEC 210.8 (A)(2) and outdoors (NEC 210.8(A)(3) . . .  

Note: A GFCI “circuit breaker” can not be used along with a GFCI “receptacle” at point of use; that would be redundant, only a standard electrical receptacle can be used if a Dual Function circuit breaker is installed in the MSP.

NOTE: Each GFCI circuit breaker has a test button to initiate a—monthly—test (UL 943). 

Photo Courtesy Of Schneider Electric HomeLine Plug-On-Neutral

ARC-FAULT CIRCUIT INTERRUPTER (AFCI) An AFCI is a circuit breaker that provides “fire protection” by detecting a break, or partial break, in wire which causes arching (Excessive heat). This can be caused by a nail or screw penetrating a wire hidden behind a wall. Most AFCI’s are installed in living areas: bedrooms, dinning room, hallways . . .

NOTE: The National Electric Code (NEC®) requires AFCI protection for 120 volt and 240 volt single phase 15 - 20 ampere branch circuits in all living areas of a dwelling (2020 NEC 40.4 (D)(4).

THERE ARE TWO TYPES OF ARC-FAUTS

• Series Arc: A break or partial break in a series wire

• Parallel Arc: An arch between hot and neutral wires which causes them to touch

A Combination Arc-Fault Interrupter (CAFI) is able to detect both types of arc-faults.

NOTE: Combination and Dual Function circuit breakers are often confused with the other.

All of the electrical circuits in the Tiny Off-Grid House will be AFCI protected, with certain circuits combined with GFCI protection; in the form of a Dual Function Circuit Breaker.

ARC-FAULT CIRCUIT INTERRUPTER + GROUND FAUT CIRCUIT INTERRUPTER = DUAL FUNCTION (DF) CIRCUIT BREAKER A dual function circuit breaker combines the series/parallel benefits of an arc fault circuit interrupter with the protection of a ground fault circuit interrupter.

CON’S OF DUAL FUNCTION CIRCUIT BREAKERS

• When activated, the DF will have to be accessed in the MSP; instead of conveniently at each point of use location

• In some environments, an audible circuit breaker maybe necessary to alert when important loads like refrigerator or a sump pump . . . are deactivated

PRO’S OF DUAL FUNCTION CIRCUIT BREAKERS

• Arc fault and ground fault protection are combined in one over current device

• More economical to purchase one DF circuit breaker than individual receptacles at various points-of-use

• Easier to identify deactivated over current protection device or concerns with the wires

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