I’ve noticed many electrical apprentices out there have a difficult time understanding why there are so many different wire types, and think that each wire is actually different somehow. They’re only different in insulation, and here’s how.
Every wire is essentially the same, for the most part. You’re either working with aluminum, copper, or copper-clad aluminum as an electrician. Each of these has their own special things you should be aware of, but really what’s important to know is the type of insulation. around each conductor.
In the NEC (National Electrical Code) there are many different tables, charts, and articles that talk about what conductors you may or may not use for certain environments. Most discuss temperature limitations as a primary factor for selection. Many also have environmental reasons for their design. As an electrician, you’re responsible for knowing what conductors you should be selecting based on the environment you’re working in.
Insulation can and does melt, often. When a conductor is not sized correctly, that conductor can become hotter than it was intended to be, and over a long enough time this can cause the insulation around that conductor to begin to break down. This over-heating can melt the insulation, creating a short-circuit or ground fault. Most of the time a circuit breaker or fuse will stop any major harm from happening, but not always.
It’s crucial to understand why certain conductors have certain insulation types, and even more important is knowing when to select the correct application for the work you’re doing.
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