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What You Need to Know About Dual Fault – and Other – Circuit Interrupters

Commercial kitchens are filled with electrical hazards. From using damaged outlets and faulty wiring to frayed electrical cords and simply touching electrical plugs with wet hands, it’s easy for workers to receive electrical shocks that cause injury or even death. Of course, in a correctly designed system, circuit breakers are designed to prevent those injuries by interrupting the flow of electrical currents.

Ground fault circuit interrupters (GFCIs) are standard in both commercial and residential kitchens, but a newer type of circuit interrupter is being used increasingly. Called a dual fault or dual function circuit interrupter (DFCI), it combines the capabilities of GFCIs and arc fault circuit interrupters (AFCIs) into one device, thus doubling its protection against shocks and fires.

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Ground faults occur when the neutral wire that should take excess energy away from an outlet fails or when other conductive elements, like water, contact the circuit and create a quicker path to earth. Without a ground wire, electrical current energizes the outlet and equipment plugged into it. Anyone touching the equipment or the outlet can receive a significant electric jolt.

GFCIs use a ground wire to prevent that. The 2017 National Electric Code (NEC) section 210.8(B)(2)  requires GFCI protection for all commercial kitchen outlets (Technically, AIEI News points out, the NEC specified all 150-volt single-phase receptacles that are 50 amps or less and all 150-volt three-phase receptacles that are 100 amps or less.)

Courtesy Square D

Arc Fault Interruptors

Arc faults, in contrast, are caused by damaged, overheated, or stressed wiring or devices. Arc fault circuit interrupters distinguish between the normal arcs associated with turning on equipment and the unwanted arcs caused by overloaded circuits or other faults. When a dangerous arc occurs, the AFCI immediately interrupts power to the circuit, thus reducing the risk of fire. (Arc faults can produce temperatures above 1,800°F with only one amp of current flowing. PVC coating ignites at temperatures as low as 454°F.) 

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During the past few years, AFCIs have been improved to monitor three types of arcing: line-to-neutral, line-to-ground, and series arcs. These are called combination arc fault circuit interrupters. (CAFCIs).  

Dual fault circuit interrupters respond to both ground and arc faults in one breaker. These circuit interrupters provide more protection than either ground or arc fault circuit interrupters alone.

On the negative side, some electricians say DFCIs trip easily. Installing them isn’t a simple matter of swapping out breakers, however. DFCIs are larger than the circuit interrupters they replace. Therefore, adding DFCIs to an electrical panel requires also replacing the circuit box with one designed specifically to accommodate DFCIs. The added protection, however, could be worth the extra work.

The 2020 NEC

The 2020 NEC will be released in November. Early reports haven’t mentioned any DFCI requirements for commercial kitchens, but awareness of their value is growing at the National Fire Protection Association, which writes the electrical code. The mandates for increased electrical safety suggests they will become increasingly common in areas prone to multiple types of electrical hazards.