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Usually yes. A typical 480 volt panel is a 3 phase panel with 480 volts line-to-line and 277 volts line-to-neutral. However, I did once see a panel that was 480 volts, 3 phase, but because it served only motors it did not have a neutral. (a 3 phase motor doesn't use a neutral.)
Similarly, if a panel uses only 2 legs of a 3 phase 480 volt system, which would be called single phase, it would not require a neutral if it only feeds 480 volt single phase loads.
But I find the idea of no neutral to be extremely unusual and in my one personal experience, I blamed it on the age of the system. In 16 years of commercial and industrial construction I have never installed a 3 phase panel without a neutral and all my work is designed by engineers.
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How is a 15 amp 277 volt lighting circuit wired at the panel?
The voltage of 277 volts is the wye voltage of a three phase 480 volt distribution. In the 480 volt CDP (Central Distribution Panel), you will need a 600 volt rated single pole 15 amp breaker installed in the CDP. The load will be connected to the output terminal of the breaker and the other conductor will be connected to the neutral bus in the CDP. The minimum size conductor for the 15 amp circuit will be a #12 copper conductor.
How do you hook up a water heater with red black and white wires?
Sounds like it is a 220-240 Volt hot water heater. The black and red are connected to the 220 volts supply and the white is connected to Neutral. At the breaker panel red and black connect to the 2-pole 220 volt breaker and white goes to the neutral bus bar.
I am adding a 30 amp sub panel - the problem I have is the neutral bus is full what are my options?
Best answer - If panel can accept, add an additional bus on the other side and bond the two together. Least desirable answer - split bolt the neutral to one of the existing. Under no circumstances should you place multiple wires under one terminal. <<>> The neutral wire for the sub panel will only be a #10 conductor. Neutral wires can be doubled up under a single screw in the neutral bus. Turn the main breaker off to do this installation. Double up two #14 neutrals to make room for the #10 neutral wire. There is no code rule as to how many wires can be installed under a terminal on the neutral bus. There is a code rule though about not doubling up circuit feeders under one breaker terminal.
What type panel does a 4 pole breaker require?
The panel and breaker have to be of the same manufacturer. This way the breaker will fit into the panel. If the panel has a push in bus bar, the breaker must also be the type to accept the bus bar. If the bus bars in the panel are of the bolt in type then the breaker also has to be a bolt in breaker.
What color should the wires be in a 120v system?
It depends. In a typical US residence with 120/240v single-phase power, the ground wire will be green, the neutral will be white, and the hot conductor will be either black or red depending on which phase it is connected to. Odd numbered breakers (1,3,5, etc.) are black, and even numbered breakers are red. You will measure 120v from black to white, also 120v from red to white, but 240v from black to red. In a commercial building with 3-phase 120/208 power, ground and neutral are the same color, but there are 3 hot colors - black (a-phase) red (b-phase) and blue (c-phase). As you run down a line of breakers from top to bottom they will be wired: black red blue black red blue etc. You will measure 120v from any of the 3 hot colors to white (neutral) but 208v from black to red, red to blue and blue to black.
