Modern facilities rely heavily on electricity to operate just about every type of machine. Due to this fact, there is obviously going to be massive electrical currents running through wires, and into machines, at all times.
In the vast majority of cases, this current will flow through the system without any problems, and provide power to all the necessary machines. Occasionally, however, there is a problem in the system and the electricity ‘escapes’ from the wires. When this happens, it is considered a fault current.
Facilities must do everything they can to identify what potential there is for a fault current, and take precautions to minimize the risks associated with them.
Behavior of Electricity
Like all natural things, electricity follows the laws of nature. When it comes to preparing for fault currents, the most important law to understand is that electricity will always take the path of least resistance when it travels.
Since electrical wiring is made to allow electricity to travel easily, and make it difficult for the electricity to escape, it normally works without a problem. In the event that something happens that makes it easier for the electricity to travel outside the wires, however, it will escape. The most common example of this is a short circuit.
Short circuits can be caused by many different things, but the basic concept is that something causes a path of very low resistance to open up for the electricity to take. This creates a high current flow out of the normal electrical system, and toward whatever that new path may be.
When this occurs, there is significant risk of an arc flash, which can cause fires, electrocution or other damage. One example of this would be if someone accidently cuts into an electrical wire with a shovel. The electricity will immediately leave the wire, and travel into the shovel, since there is very little resistance.
From there, it may travel into the person holding the shovel, or go through the air toward another piece of metal or the ground. What can make this type of fault current particularly dangerous is the fact that the electricity from throughout any connected system will travel out toward this low resistance area.
Until the source of the electricity is cut off (either manually or through a circuit breaker of some sort), it will continue flow out of the wiring and through whatever that path of resistance may be. This, of course, is extremely dangerous.
Common Causes of Short Circuits
Knowing what will happen in the event of a short circuit is important, but it is also a good idea to take some time to learn about the most common causes of short circuits. This can help you with prevention, as well as knowing where to place warning labels for maximum efficiency. The following are some of the most frequent causes of these dangerous events:
Animals – It is not uncommon for an animal to either chew through an electrical wire or get into a circuit box. When this happens, the electricity typically passes through the animal (killing it) and then to whatever the closest conductor of electricity may be.
Digging – When people are digging around areas where there are buried power lines, this can cause a short circuit if the digging equipment comes into contact with the electrical wires.
Moisture – Both indoor and outdoor electrical systems are susceptible to moisture levels. Water conducts electricity well, so if it gets into the wiring or other systems, it can quickly cause a short.
Broken Wires – With everything that is going on in most facilities, it is easy to see how a wire can get broken. When this happens, the low resistance path within the wire is no longer available, so the electricity has to find a new place to travel.
Overloads – If a generator malfunctions, or there is some other electrical fault, a specific wire may be overloaded with electricity. When this happens, the wire can’t contain it all, and it will short out.
Insulation Problems – Electricity is kept within the electrical wires by non-conductive insulation. If that insulation is worn away or is otherwise damaged, the electricity may make its way through, causing a short circuit.
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Calculating Fault Currents
Facilities are required to know what the potential fault current is for their electrical systems, so proper precautions can be taken to help ensure everyone is safe. Knowing this information is required by the National Electric Code (NEC) 110.24(A).
In order to calculate the fault current, you will have to use Ohm’s Law, which states that the current (I) is equal to the voltage (V) divided by the resistance (R). Therefore, the formula that is used looks like this: I=V/R. This mathematical formula essentially shows that when the resistance becomes very low (such as with a short circuit) the current becomes quite large. This results in a situation in which anyone or anything in the area is in serious danger.
Fault Current Labeling
Once you have calculated the potential fault current, you need to make sure to label the equipment with this information. Having this information clearly visible on any machines, major cabling, and the source of the power (generators, transformers, ect) will help anyone working in the area make safe decisions.
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The labels should include information about the strength of the potential current, as well as any risks of arc flashes that may occur. In most cases, this type of information is primarily going to be used by maintenance personal who are working on the machines or the electrical systems.
Creating Custom Fault Current Labels
LabelTac 4 PRO – Print Custom Fault Current Labels
One important thing to keep in mind when labeling any type of equipment with electrical information is that you need to include the specific details related to that machine. Specifically, determining how much electricity is running through, and calculating the fault current for that machine. Once calculated, you will want to put that on the label so everyone is aware.
In addition to the calculations themselves, it is important to include the date on which the fault current calculation is made. This is because as machines are updated and improved, the fault current calculations can change. An example of the text that may be used on a machine might be, “Maximum Available Fault Current 50,500 Amps. –August 26, 2014.
All of this information is required by the National Electrical Code (NEC) 110.24 regulations, which went into place in 2011. So, if you have any electrical labeling in your facility that is older than 2011, you are likely not in compliance and it is important to take some time to update all your labels.
With that in mind, you need to have custom labels printed off for each area of your facility.
You have two main options to consider when it comes to having these printed labels made. The first option is to order them from a third party printer. This can be quite expensive, and it may take several days or even weeks to have the labels arrive.
The other option is to purchase an industrial label printer for your facility. There are many different makes and models that you can choose from, including several different options from LabelTac. These printers will allow you to create custom labels and print them immediately.
This is, by far, the fastest way to make sure you are staying in compliance with all the labeling requirements, including those related to fault currents. More importantly, you will be taking a step toward keeping everyone in your facility safer, especially those who work directly with electrical systems.
Taking Fault Current Safety Seriously
All facilities need to make sure they are taking fault current safety seriously. This starts by making sure your electrical system is properly installed and maintained, and continues by following the electrical standards regarding labeling.
Proper labeling is not only a good idea because it will help to improve the overall safety of your facility, but it is also a requirement for any facility that needs to be in compliance NEC regulations. Take some time to review all the labels in your facility that are focused on electricity and fault currents and make sure they are updated and accurate to reflect the 2011 NEC 110.24 regulations.
By being alert to potential hazards, your facility can minimize the risk of an arc flash, or other short circuits that could cause serious hazards for the facility and the individuals working near the electrical systems within. Remember, knowledge is key in these areas so make sure your facility is focused on clearly labeling all hazards, especially those related to electrical fault currents.