I'm sorry to bother you guys, but I am confused and frustrated. I have researched this for days and simply cannot find a straight answer. I'm trying to differentiate between common and neutral. I'm preparing for a NEC exam. I'm asking about basic USA household wiring (240VAC, 120VAC, 24VAC)-- non-industrial. For example, I'm not referring to "common", as it is used in a split capacitor, 3 and 4 way switches, etc. I'm 60, and have worked with residential wiring for 25 years.
Please try to explain it to me like I'm a dummy! When can these terms be used interchangeably and when can they not be used.
My current understandings:
1) All neutral wires are common wires, not all common wires are neutral wires. Neutrals have white or grey insulation and must be grounded, whereas a common, depending on the application, may have insulation of various other colors. and may be a hot lead (ex. split capacitor).
2) A common is the lead that is common to all devices from the same control voltage source. It usually has no contacts, switches, etc between it and loads. A common must go to more that one of something. So if a main panel has only one 120VAC single pole 15 amp breaker that goes to only one single outlet (not duplex outlet)-- there is no common and only a neutral that technically could not be called a common.
3) Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. It carries current away from the device back to the electrical panel and ultimately back to the ground or source. It completes the circuit. It is (in this simple context) also called the grounded conductor.
4) If two separate 120VAC phases share a neutral, then the neutral is also a common.
5) The neutral wire is specifically designed to return current in an electrical circuit, while the common wire can refer to various return paths in different contexts, including switches or ground connections.
6) The power company says that for the power lines coming from the pole to the service entrance, the return is a neutral and not a common. Yet the neutral serves two phases-- so isn't that a common as well?
7) I've read this: "In a 120V system, there is no neutral, but we all call the white wire a neutral (need three wires to have a neutral)." Is this true??
OMG, thank you in advance for your time. My name is Gil...
Please try to explain it to me like I'm a dummy! When can these terms be used interchangeably and when can they not be used.
My current understandings:
1) All neutral wires are common wires, not all common wires are neutral wires. Neutrals have white or grey insulation and must be grounded, whereas a common, depending on the application, may have insulation of various other colors. and may be a hot lead (ex. split capacitor).
2) A common is the lead that is common to all devices from the same control voltage source. It usually has no contacts, switches, etc between it and loads. A common must go to more that one of something. So if a main panel has only one 120VAC single pole 15 amp breaker that goes to only one single outlet (not duplex outlet)-- there is no common and only a neutral that technically could not be called a common.
3) Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions. It carries current away from the device back to the electrical panel and ultimately back to the ground or source. It completes the circuit. It is (in this simple context) also called the grounded conductor.
4) If two separate 120VAC phases share a neutral, then the neutral is also a common.
5) The neutral wire is specifically designed to return current in an electrical circuit, while the common wire can refer to various return paths in different contexts, including switches or ground connections.
6) The power company says that for the power lines coming from the pole to the service entrance, the return is a neutral and not a common. Yet the neutral serves two phases-- so isn't that a common as well?
7) I've read this: "In a 120V system, there is no neutral, but we all call the white wire a neutral (need three wires to have a neutral)." Is this true??
OMG, thank you in advance for your time. My name is Gil...