chipstakk Posts: 2, Reputation: 1 New Member #1 Apr 13, 2009, 06:31 PM
Differnce between neutral grounding and separated grounding
What is the difference between neutral and separate grounding?? Why and when do you defer between them?? Basically why do we ground, what's its purpose and what are the differences between the varying methods.

I hope I don't sound dumb but the US NAVY nuclear electrical school didn't teach me apparently LOL
 tkrussell Posts: 9,657, Reputation: 724 Uber Member #2 Apr 14, 2009, 04:47 AM
This is a complex issue to answer briefly.

A neutral is a return for a circuit, and is grounded at the panelboard and utility transformer, so that only one wire of a circuit is live.

However, a grounded neutral is a current carrying conductor, since it is the return for a circuit. You can touch it and not feel a shock, but the current being drawn by the circuit can be measured flowing through the conductor.

If you break, or open, an active neutral conductor, you can measure 120 volts across the two neutral conductors, so touching both or a grounded surface will result in a shock.

A "ground" is technically referred to as a equipment grounding conductor (EGC), intended to connect any metal raceway and any exposed metal of an appliance or device, and only carrys current during a ground fault condition.

It is often called a "safety" ground, as it is there for the sole purpose of conducting any voltage imposed on a exposed metal to ground.

If an appliance fails and the live wire inside shorts to the metal frame, the ground allows the ground fault voltage to drain, so to speak. An equipment grounding conductor must have low impedance to allow current to flow quickly and high, so the overcurrent protection device, AKA fuse or circuit breaker, opens, or trips, thereby removing the dangerous condition of a live metal frame.

There is much misconception that a neutral, because it is grounded, is a ground. And then misconception gets carried over to the EGC that since an EGC is grounded, it is a neutral.

Each conductor has it's specific purpose, and must be kept separated in all electrical boxes, outlets, devices, and the two are only connected together at a specific location in a building's electrical system, typically at the Main Service Disconnecting Means, or Main Switch. This is where the neutral, EGC and grounding electrode conductor all connect.

If a neutral wire gets connected to a EGC anywhere in a building, there is a potential for sending current thruout a building's grounding system, and at any location something is not grounded properly a potential of shock hazard, or arcing due to loose connections.

Like I said, a complex issue to explain in a few words. Hope I got my point across. There is a wealth of information, diagrams, etc, on the web for you to review for a more detailed explanation.

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