The major difference between intrinsic safe and non-intrinsic safe cables is that intrinsic safe cables are used in hazardous environments, whereas non-intrinsic safe cables are used in non-hazardous environments.
When you are working in an industrial environment, safety is a must. Safety hazards, if bypassed, can endanger either the lives nearby or can endanger the nearby environment. Safety mainly relates to fire and ignition hazards. This is because any chemical reaction or improper working or neglecting safety standards leads to fire.
So, if the equipment you are using either supports ignition or gets ignited easily, then it is of great threat potential for others. All this depends on how hazardous the nearby environment is. For this environment, a special term called intrinsic safety is used; which means the devices supporting it will either not ignite easily or will not support ignition. One of the most important things used is cables. Cables too are classified as intrinsic safe and non-intrinsic safe.
What is Intrinsic Safe Cable?
Short circuits and sparks are common terms related to electrical circuits. If any of these things happen and a fire occurs, then it is necessary that the devices which are being used there do not catch fire or they do not support fire triggers.
If they start to support fire, then they will get damaged and then, it will spread fire to nearby sensitive items which can hamper the overall system. This is where the term intrinsic safe comes in. An intrinsic safe device prevents sparks or other types of fire hazards from occurring in a hazardous environment.
If you are working in a hazardous environment and if you use devices or do some actions which will create fire instantly, then it will affect everyone around you. So, it is required to first understand the safety environment levels or types of hazards.
Hazardous elements are classified mainly into three categories – first comes gas and vapors, second comes combustible dust (metals, metal alloys, charcoal, plastics, carbon black or wood) and third comes fibers and debris.
Each of these elements has different levels of hazards and fire factors related to it. Also, it is important to do risk assessment activities for analysis before starting any work. An intrinsic safe environment is thus one in which any apparatus or wiring will not support ignition in a hazardous environment, due to spark or other such thermal effect.
Intrinsically safe cables have a blue color and thus, it becomes easy to identify the cables by looking at their color. The cable has tough sheathing materials like polyurethane around it to protect it from mechanical damage.
Generally speaking, the low values of voltage and current present in IS circuits allow the use as IS cables that are normally used for field instrumentation, provided that their properties have been taken into account (as previously said), in the calculation of the total properties of the circuit. The field instruments like transmitters, valves, and switches installed in Hazardous areas are intrinsically safe and Exi certified.
What is Non-intrinsic Safe Cable?
Non-intrinsic safe cables are not designed for use in hazardous environments. The hazardous environment has flammable gases, vapors, and combustible dust that may that acts as an ignition source. The non-IS cables if used in a hazardous environment can cause sparks and fire if the cables get excessively heated up in the case of overloading and short-circuiting.
Non-intrinsically safe cables must not be in hazardous environments, like refineries, chemical plants, and mining sites. In these areas, intrinsic safe cables and other electrical equipment must be used to prevent accidents and for ensuring the safety of the personnel and properties.
Non-intrinsic safe cables may be suitable for non-hazardous areas where the probability of ignition is low or does not persist. These types of cables do not have the degree of protection and safety features as intrinsic safe cables have. If we use non-IS cables in hazardous environments, it may cause significant safety risks. The cables and other equipment used in the non-hazardous area may be of non-intrinsically safe and non-Exi certified.
Difference between intrinsic safe and non-intrinsic safe cables
Now that we have understood the concept of an intrinsically safe environment, let us move on to our topic which deals with one of the most used electrical things; cables. Cables, as discussed, come in two types – one which is intrinsic safe and one which is not intrinsic safe. Cables in both types come in either single-pair or multi-pair shielded form. Non-intrinsic safe cables are used in non-hazardous environments, whereas intrinsic safe cables are used in hazardous environments.
So, what separates intrinsically safe cables from non-intrinsic ones? Because cables are the main carriers of current, it is important to consider their intrinsic factors before laying them out. Any lag in this will not prevent them from catching fire or in short, they will lose properties of not supporting ignition.
First of all, they are provided with additional sheath layers for avoiding mechanical damage. Second, the main electrical properties to consider are capacitance and inductance. They have different values than a non-intrinsic safe cable and must be maintained during operation for avoiding any fire contact. For that, the length of the cable is also to be considered when designing.
So, the main factors that differentiate them are length, capacitance, and inductance. A cable designer takes note of all these factors before designing a cable that will not support fire or ignition. Yes, if it crosses a very high limit, then it will catch fire. But generally, a normal spark or other hazards discussed earlier will not trigger ignition in the air and thus, fire will not happen. A non-intrinsic safe cable when used in a hazardous environment will easily catch fire even in small sparks or wire cuts.
