Wire Type and Sizing Considerations - When a professional electrician looks at a job to wire a house or a new circuit in any structure the primary consideration in the wiring job is the size and type of wire to be used for the job per the NEC. The same for a plumber when looking at a job the plumber will size the pipes based on the number of gallons needed to carry the proper amount of water to its destination. If the pipe is too small then the water needed will not reach its destination. This is almost the same for electrical wire except under-sizing electrical wire is dangerous.
Wire Type and Sizing Considerations - New Circuits and Wiring for Equipment Circuits
An electrical wire carries voltage but it is the current rating of the power loads which is the primary factor in determining the size and type of wire to be used for the job. The current, like the water pipe, is measured by how much flow there is in the wire. If the wire is too small and the flow too fast then the wire gets hot. If it gets too hot then the insulation melts and a dangerous condition exists. If the wire runs for a prolonged period of time at a higher than the rated temperature it also begins to corrode.
There are corrosive effects at terminal connections. Eventually, the corrosion and the excessive heat will cause the wire to become brittle. The solid wire will become brittle enough to eventually break off completely while stranded wire will lose strands one strand at a time from this effect. This causes the wire to become smaller and the heat increases. Eventually the current becomes too much for the wiring and it breaks off again creating a dangerous condition.
Wire Type and Sizing Considerations
The equipment or device being supplied electricity from this wire, when it breaks, ceases to function while a live wire is hanging inside a control panel or other panel. This is why it is very important to properly size electrical wires for any type of electrical work and not to overload existing circuits in homes and businesses. Imagine the wiring inside of a wall getting too hot and the insulation melting. This creates a dangerous electrical situation and also is a fire hazard.
National Electrical Code Ampacity Tables | Wire Type and Sizing Considerations
* The National Electric Code (NEC) specifies that the over-current protection device (breaker, fuse, or motor over-load) not exceed 15A for 14 AWG, 20A for 12 AWG wire, and 30A for 10 AWG wire. Always follow the current NEC tables for sizing.
|Maximum Ampacity for Copper|
Conclusion | Wire Type and Sizing Considerations
Additionally, it is very important to use the proper wire and wire sizes when wiring electrical appliances. It is a huge safety factor in selecting the correct wire and the correct size for the circuit. The entire National Electrical Code is devoted to electrical safety that includes using the proper wire and wire size for various circuits and applications.
Lastly, it also important to properly terminate the wiring when you are finished. Electrical loose connections can cause issues with equipment that can lead to failure of the equipment and worse, a fire. This is especially true for aluminum wiring. It is a good idea to tighten the connection and then schedule a revisit to the terminations to ensure they are tight especially when ambient temperatures fluctuate. Make sure you use the right wire, the right wire size, and that the terminations are tight. Then you should not have any problems.
Wire Type and Sizing Considerations
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