HOW CABLE QUALITY CAUSES ELECTRICAL FIRES
Electrical fires can be some of the hardest to predict, prevent, and extinguish, making them among the most devastating.
But proactive preventive measures can be taken to prevent such catastrophes from occurring, and the first place to start would be equipping oneself with knowledge of electrical systems in general and electrical cables in particular.
A lot of electrical fires occur in homes where testing, adherence, and enforcement of electrical standards before, during, and after electrical installation works is usually an afterthought and, in a lot of cases, a non-consideration, unlike in the commercial sector.
Given that electrical cables are usually hidden in walls and ceilings, smouldering fires can be hard or impossible to detect, and when they are, it can sometimes mean it’s too late.
Smouldering fires can give off gases, which, when they come into contact with oxygen, can ignite and lead to a raging fire.
Cable quality
While the causes of electrical fires caused by cables are many and varied, inferior and substandard cabling is usually the biggest culprit. When an electrical installation or conductor, like a cable, heats up excessively, it can culminate in a smouldering fire.
Oftentimes, cables heat up due to being unable to handle the amount of current passing through them, but there are several other reasons that might cause a cable-related electrical fire.
There are two main quality aspects of an electric cable that can potentially cause fires during usage:
Poor conductor or insufficient cross-section
A cable with a poor conductor or insufficient cross-section can cause the conducting lead to heat up and damage the cable sheath. The insulating sheath can melt and expose the live conductor, which can come into contact with another conductor and cause a short circuit and a potential fire.
Poor conductors also break off easily and can cause incomplete or loose connections and contacts, which can result in sparks.
Additionally, poor conductors reduce the cables conducting ability, which can result in a drop in voltage that eventually shortens the lifespan of electrical appliances or makes them work less optimally.
Low-quality insulation layer
Low-quality insulation can crack over time when exposed to heat or when the cable is bent. A crack that’s wide enough might expose the live conductor or let in moisture that would result in a short circuit.
Poor-quality insulation is also unable to tolerate heat generated by the cable or from outside sources and can thus melt and expose the live conductor, which opens the cable to short circuits or moisture.
How does a cable fire start and what causes it?
Damaged insulation: the insulating sheath is supposed to protect the live conductor from coming into contact with other objects or conductors. When the insulation is worn or broken and a part of the live conductor is exposed, a short circuit might occur when it comes into contact with a foreign conducting object. A continuous short circuit can eventually cause a smouldering fire.
Cable breaks: Particularly for stranded cables, a break can cause electric current to keep flowing on the corresponding cable strands, which have a smaller surface area than is required, leading to overheating and eventually a smouldering fire or short when the insulation is damaged. Additionally, very tight bends cause flow resistance, which causes the cable to heat due to current flow resistance.
Poor workmanship and installation practices: cables strung and clamped too tightly together can cause a fire when they generate heat that is not dissipated and thus can melt the insulation over time, causing the live conductors to be exposed.
Looseness: Loose plugs and clamp connections can also cause cable fires as the contact point is very small, which can cause overheating or sparks.
Electrical arcing: electrical arcing is when an electric charge jumps from one conductor to another and occurs when a circuit becomes overloaded or overheats. Overheating can damage the circuit breaker and cause it to malfunction, where it continues supplying power when a short circuit occurs rather than tripping and cutting off the power supply. Some of the causes include loose connections, damaged insulation, and improper installation practices.
Age factor: corrosion and oxidation contribute to loose cable connections over time, which can result in overheating or sparking. The resultant fumes and sparks can eventually cause a fire.
Overloads: when too much current is flowing through a cable that is not rated to conduct and handle the current flowing through it, the cable eventually overheats due to resistance. Numerous extension cords and power strips can also overload and consistently weaken the individual power line over time. High currents to power loads and appliances on the extension cords can lead to increased stress on the cable, making the insulation porous and at risk of smouldering.
Substandard or untested electrical products that are fed by the electrical cables can also contribute to cable fires, especially if they blow up and draw way more current than the cable is rated for.
Environment: cables installed in places where they’re continually exposed to high temperatures can degrade the insulating material, causing the exposed live conductors to come into contact with foreign conducting objects or materials, sparking a short circuit.
How to prevent and forestall cable fires
Quality cables: avoidance of substandard and low-rated cables is the first and most important measure. All cables should be rated for the particular function and loads they are supposed to support. This can be ascertained during the purchase of the cable, where aspects such as the manufacturer name and technical specifications such as conductors and load rating details are clearly specified.
Insulation: checking for frayed, kinked, or crushed insulation on the cables is important. The point at which the cable is crushed or kinked is likely to heat up due to flow resistance, and a damaged sheath can expose the live cable and cause a short circuit.
Overloading: care should be taken not to overload the cables. Overloading can be a result of having fully loaded sockets and splitting or branching sockets through extension cords and extra socket strips. Other ways can be through electric heaters and other power-hungry appliances.
Installation practices: electrical cables should be run by qualified electricians who are conversant with and would adhere to industry-standard safety practices. Such practices can include the use of PVC conduits and cable trays, which would protect the cables from damage and offer support and ventilation.
Loose connections and contacts: defective contacts and loose connections can cause sparks or lead to overheating, eventually culminating in smouldering fires. Such contacts and connections ought to be regularly checked, maintained, and repaired if needed.
Electrical cables also ought to be installed or run in well-ventilated spaces where there is no danger of heat getting trapped and causing the cables to overheat.
Thermographic inspection: a thermal imaging camera, used particularly by fire-fighters to see areas of heat through smoke, dark areas, or heat-permeable barriers, can be used to examine electrical equipment and installations and determine their surface temperature to check for overheating.
Smoke alarms: smoke alarms can sometimes be used to offer advance warning of an impending fire by detecting smoke from smouldering cables and electrical appliances, and if noted and taken care of early enough, a disaster may be averted.
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