As DrMoishe points out some pieces of equipment use mostly 240 volts and very little 120 volt power. It is the 120 volt power that uses the neutral. Therefore the National Electrical Code allows the downsizing of the neutral in limited application.
Can a neutral wire be undersized?
The neutral (grounded conductor) cannot be smaller than the required size of the GEC (per table 250.66) and is not required to be larger than the largest ungrounded conductor.
Why is the neutral wire smaller?
Here the main purpose of the neutral wire is to ground the fault current in case of unbalance or harmonics. Here the neutral wire does not carry the load current. In this case, the size of the neutral wire may be less than phase wire.
Why neutral conductor is oversized?
You must size the neutral conductor to carry the maximum unbalanced current in the circuit (i.e. the largest load between the neutral and any one ungrounded phase conductor).
Under what circumstances can a neutral feeder be reduced in size?
Under certain conditions of use, the neutral may be reduced in size. For example, a feeder or service supplying household electric cooking equipment and dryers may have a demand factor of 70 percent applied to its total load, based on the number of appliances (dryers) present.
Why neutral is half size?
For three phase circuits that serve phase to neutral connected loads, the neutral can be reduced in size when the operation of the system will result in partial cancellation of the neutral return. The reduction in the size is determined by electrical codes.
Can you downsize the neutral on a 200 amp service?
For a 200 amp service you can downsize to the size of the gec, if the calculated load permits. Usually that is a number 4 copper conductor.
Can you downsize the neutral on a residential service?
It is possible to downsize a feeder or service neutral according to the calculations in the National Electrical Code here: 220.61 Feeder or Service Neutral Load. (A) Basic Calculation. The feeder or service neutral load shall be the maximum unbalance of the load determined by this article.
What is the purpose of a neutral conductor?
Neutral wire carries the circuit back to the original power source. More specifically, neutral wire brings the circuit to a ground or busbar usually connected at the electrical panel. This gives currents circulation through your electrical system, which allows electricity to be fully utilized.
What size neutral do I need for 100 amp service?
When it comes to the lines connecting master and secondary panels, where the line will carry as much as a full 100 amps, use a 2-gauge non-metallic sheathed electrical cable. The cable must contain one or two hot wires depending on your needs, one neutral wire, and one ground wire. Each wire should be 2-gauge in size.
Why neutral wires have lesser gauge than phase wire?
In a three phase system neutral wire is thinner. Because neutral will carry only leakage or unbalance current of three phase. Unbalance neutral current constitutes very small percentage of phase wire.
What is the sizing of neutral conductor for the conductor core made of copper?
The size of the neutral conductor is at least equal to 16 mm2 in copper or 25 mm2 in aluminium.
Does neutral conductor carry current?
The neutral wire will be connected to the earth ground, the color of the neutral wire could be grey or white. During normal operations, the neutral wire will carry current. We can see neutral in most of the electrical equipment, mostly in non-linear loads.
How many amps should be on a neutral?
Senior Member. Assuming a 120/240 single phase source, I believe that the neutral current should be the difference between the two ungrounded/hot conductors. If you have 8 amps on A and 6 amps on B, I would have expected 2 amps on the neutral.
Why does my neutral wire have voltage?
The voltage you are seeing on the neutral wire is conducting through that other load from the hot. Your voltage tester is detecting voltage without drawing current so the resistance of the other load is not seen. Try disconnecting/turning off all other loads on that circuit.
How much current is on the neutral wire?
On any individual circuit (lamp or 120V outlet) the current in the neutral in that circuit is equal to the current in the “hot” wire.
Does neutral carry voltage?
The neutral wire is often said to have zero voltage on it. If you touch that wire on a live system, however, you will often find out very quickly that technically having zero voltage is very different from meaning there is no electricity present.
What happens if neutral is not grounded?
Grounding neutral provides a common reference for all things plugged into the power system. That makes connections between devices safe(r). 2. Without a ground, static electricity will build up to the point where arcing will occur in the switchgear causing significant loss in transmitted power, overheating, fires etc.
