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Let’s face it…the national electric code book is probably the most difficult construction document to read and understand. It’s written like a court document in legalese, using terms none of us use in the field, for the sake of liability and C.Y.A. These are 11 terms that are used in the NEC that I feel people struggle with understanding when they first buy a code book.

 

#1 – UNGROUNDED CONDUCTOR

Ungrounded conductors are the “hot” wires we deal with. They’re normally the phase conductors that people think of as black. They’re called ungrounded, because they are the conductors what we DO NOT want to every be grounded – intentionally or unintentionally. We want them supplying power to a load, not supplying power to metal surfaces or to the earth – so they’re different than GROUNDED conductors.

 

#2 – GROUNDED CONDUCTOR

Grounded conductors are the exact opposite of ungrounded conductors. Grounded conductors are what we in the field call a “neutral.” This is the white wire in a 120v circuit (US). The reason this is called the grounded conductor is that in the transformer where power is being derived, there is a coil (there may be several) of wire. One end of this wire is one of our hots (ungrounded conductor), and the other side of that same coil of wire is where our other phase comes from. So we get L1 and L2 (240-volts) from one piece of wire shaped into a coil. Well when you take the mid-point of that coil and bolt another conductor to it, that middle point is what we call the NEUTRAL POINT. We can hook a conductor to this and bring it down to the earth to ground it. So now we have a responsible reference for stable voltage, and have mechanically attached it to the earth so the earth is at the same potential. This also provides us with a half-voltage between L1 and L2’s 240-volts – so we can have 120-volt circuits as well.

 

#3 – EQUIPMENT GROUNDING CONDUCTOR

Equipment grounding conductors are the conductors that connect the metal housing of equipment back to to the neutral (grounded conductor) at the service. This is the, typically green or bare conductor (US systems) that we call out in the field…the ground. These conductors are sized based off of the breaker ahead of the equipment and need to be run in a way to ensure a low-impedance path for fault-current to take in case something bad happens in an electrical circuit.

 

#4 – GROUND-FAULT

A ground fault is an accident, we’ll just start with that. It’s when an ungrounded conductor (hot) comes into contact with a piece of metal. This piece of metal will become energized if it is not intentionally grounded. The reason we ground the metal enclosure of equipment is so that if this happens, that equipment doesn’t just sit there energized while someone walks up, touches it, and gets shocked. If we ground the equipment, it allows the current to return to the neutral, completing a circuit which assists in tripping the breaker for that circuit. I cannot express enough, the importance of proper grounding and bonding. A lot of electricians don’t understand the dire importance of ground-fault protection.

 

#5 – GROUND-FAULT CIRCUIT-INTERRUPTER (GFCI)

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