## 1 Introduction
### Glowing Condition and Arc Fault  
In this paper, we will focus on series-type low-current arc faults in commercial electrical appliances [3]. It is well known that a worn-out electrical socket or plug has the possibility of causing a fire due to poor contact conditions. The glowing condition occurs when electrical current flows between two contact points that are composed either of different or the same materials. The contact point accumulates heat from the Joule heating effect, itself a result of contact resistance. Contact resistance is the actual resistance at the contact point or, if contact is small, the conducting spot between two points. In classical contact theory, as it relates to electrical fires, the amount of heat that is generated by contact resistance is proportional to the amount of current passing through the contact point [4]. If the contact point has a high resistance, then more power will be dissipated at the contact area, eventually causing the material to glow \"red hot\". The material around the glowing area is composed of molten oxides of the original construction material, such as iron oxides for the screw and nut fixtures and copper oxides for the wire terminals. High temperatures at the contact points can create a fire hazard if any flammable materials are near them when they begin to glow and become molten: wire housing insulation, which is usually made from wool and cloth, is just such a material. The heat from the glowing area can also conduct outward, thus heating the whole conducting area and creating secondary glowing conditions near the primary one. The glowing connection phenomenon frequently happens in areas with a loose connection near the electrical terminal and is even more common when the construction material for the terminal is less conductive, such as the steel used for the screws. Terminals with steel screws can be found in older residential areas, the same areas where electrical fires are most likely to occur. Newer electrical terminals in modern buildings are made of electrical-grade brass or copper to reduce contact resistance, which likewise reduces the chance of initiating a glow. However, electrical contacts made from copper or an alloy of copper are responsible for glowing connections more so than any other type of connector, a point which will be discussed further in this paper. The primary hazard associated with glowing connections is the subtlety of the phenomenon. A device or an appliance could have a glowing connection but appear as though it were functioning normally. The only way to detect this phenomenon is to monitor the current that is delivered to the load and look for an abnormal level of current draw. Such monitoring is used only in places such as factory settings where the environment contains something that could be a fire hazard (wheat dust, saw dust, etc.). When the critical temperature is reached, both the terminal and any electrical device connected to it will still function normally, but the high temperature from the glow can damage the insulation and the area around the affected point, thus creating a fire hazard. In addition to contact resistance, a glowing condition can also be caused by an arc fault. Arc faults can be divided into two main categories: series arc faults and parallel arc faults. In most circumstances, arc faults occur on high-voltage switching boards where the voltage between ground and the live wire is high enough that the air between the two points of contact becomes ionized, resulting in an electrical discharge. This discharge can release an extreme amount of energy, to the point where the heat at the arcing point can damage the insulation and the support structure. In a high voltage setting, such as that at a power station, the arc-fault discharge is capable of inflicting severe burns within a fraction of a second to people who are exposed to it without protective gear.