Arc flash is a discharge of electricity that takes place due to an arcing fault between one phase bus bar and another. Because of circuitry design, flashes start when an issue with circuitry, for example, loss of insulation, triggers an electrical discharge. Once in place, notwithstanding, an arc is sustained by conductive plasma that utilizes the air as a conductor until a form of impedance douses it. Depending upon voltage and arc impedance, flashes can vary from minor to serious, with the biggest ones generating Blasts that heave shrapnel. As a specific amount of voltage is needed to trigger hazardous areas, devastating arcing commonly happens in electrical systems in which the bus voltage surpasses 120 volts.
What Averts Flashes From Happening?
Hazardous arcing has been a worry for as long as electrical systems of 120 volts or above have been in use, with circuit breakers and fuse boxes being the main vehicles for their prevention. Circuit breakers and fuse boxes help to avert two occurrences – 1. An overload, where a circuit receives a voltage that is too high to conduct along the established path. 2. A short circuit, Where low or non-existent impedance generates the ideal atmosphere for hazardous arcing. In a normal situation, a circuit exposed to a high voltage would “trip” in the case of breaker panel or “blow” in the case of a fuse box, breaking the current that would produce a hazardous arc.
To make sure that breakers perform optimally, they receive regular maintenance from trained technicians, who do arc flash hazard analysis. A well-designed analysis will comprise the following preliminary measures: (1) A one line drawing that distinguishes every electrical part by name; (2) information with respect to the lengths and cross sections of cables; (3) information in regards to the minimum and maximum fault currents present at the electrical entrance point of a building; and (4) additional building information as needed.
With these components set up, a technician performing an arc flash hazard analysis can use their information in equations provided by the NFPA or the IEEE, to ascertain flashing hazard. Then, fine-tune a breaker/fuse system to inhibit flashing hazard.