The Neutral wire should be the same gauge and size of the phase wires. Only the Earth or Equipment wire can be smaller than the phase(hot) wires.
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On a three phase four wire distribution system the neutral can be reduced in size. The neutral only carries the unbalanced load current and should be sized to that current. The highest current load to neutral of the three legs is used to calculate the neutral sizing. There is no reduced neutral allowed on discharge lighting and non linear loads. A demand factor of 70% shall be permitted to be applied to that portion of the unbalanced load in excess of 200 A.
The formula to use is, phase voltage /1.73 = phase to neutral (ground) voltage.CommentThere is no such thing as a 'phase to phase', or 'phase to neutral' voltage. The correct terms are 'line to line' and 'line to neutral'. So the above answer should read: line voltage/1.73= line to neutral voltage = phase voltage.
A phase leg connects to the neutral through the connected load.
As far as I understand, you don't need neutral line for connecting appliances that is 3-phase compilant. You only need the neutral line to connect a single phase appliance, which you connect along with one of the three lines.
Only one neutral conductor is typically in a 3 phase panel.
If the heater is rated as a 3 phase 480 volt heater then a neutral is not needed. If the voltage stated is 277 volts three phase then a neutral is needed.
On three phase services over 200 amps the electrical code allows the electrical contractor to reduce the size of the neutral wire . This saves the customer money. There are conditions as to how much the neutral can be reduced but it is not as low as half the supply conductors. The reason that the neutral can be reduced is that it only carries the unbalanced current on the three phase four wire system.
The formula to use is, phase voltage /1.73 = phase to neutral (ground) voltage.CommentThere is no such thing as a 'phase to phase', or 'phase to neutral' voltage. The correct terms are 'line to line' and 'line to neutral'. So the above answer should read: line voltage/1.73= line to neutral voltage = phase voltage.
f=c-p+1 is the reduced phase rule
For easy and quick identification of the leads, so that the user does not make mistake while connecting the leads.AnswerFor residential wiring, the earth wire rarely has a cross-sectional area that is larger than the line (not 'phase') or neutral conductors.
If the phase and neutral wires are shorted together, the voltage in the neutral wire will be the same as the phase voltage. This is because the short circuit effectively bypasses any impedance or resistance in the circuit, causing the potential difference between the phase and neutral wires to be equal.
A three phase system will have 3 phase branch circuits and no neutral.
If there is a voltage differential from phase to phase, and a conductance (inverse of resistance) between them, then current (amperes) flows. This is no different than phase to neutral, i.e. voltage across conductance generates current, (I = EC, or I = E/A) except that neutral current is zero in a true phase to phase connection.Note that phase angle is always relative. In phase to neutral, it is relative to (typically) neutral; while in phase to phase, it is relative to the other phase. By Fourier Analysis, the difference between two phases of the same frequency, but of different phase angles, is still a sine (or cosine) wave. Also, by Kirchoff's Current Law, (implied, and I will (sort of) not repeat it here), current entering from one phase and equally leaving via another phase will not reflect at all in the neutral conductor.The simple answer is that connecting phase to phase is a short circuit, just like connecting phase to neutral.CommentThere is no such thing as 'phase to phase' or 'phase to neutral'. The correct terms are 'line to line' and 'line to neutral'.
A phase leg connects to the neutral through the connected load.
As far as I understand, you don't need neutral line for connecting appliances that is 3-phase compilant. You only need the neutral line to connect a single phase appliance, which you connect along with one of the three lines.
Only one neutral conductor is typically in a 3 phase panel.
In a balanced three-phase system, the current in the neutral wire should ideally be minimal as the three phase conductors carry equal and opposite currents that cancel out in the neutral wire. However, if the loads are unbalanced, the neutral wire may have higher current due to the uneven distribution of power among the phases. This can happen when loads on each phase are different or when single-phase loads are connected between a phase and neutral, leading to increased neutral current.
It is the same as phase to neutral. As the neutral is earthed at the electricity suppliers transformer.