I have a question: for lighting in different circuits on the same floor, can the neutral and ground wires be shared?
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For example, if a floor has 20 lighting fixtures, every 10 fixtures form one circuit, and two circuits originate from the same lighting distribution box. So can these 20 lighting fixtures share one neutral wire and one ground wire? Should each circuit still have its own separate neutral and ground wire? Thank you all!
This post was last edited by qhwangyz on 2020-10-22 09:20. Ahah, this sea friend – it shouldn’t be possible; it’s necessary to follow the instructions in the diagram! Because, according to the design drawings (resulting from engineering calculations), each lighting circuit is supplied with power separately; the cables or wires used in these circuits are selected based on the requirements of 10 light fixtures (each circuit needs to have its cables and wires chosen according to factors such as the load power and current-carrying capacity of that circuit), rather than 20 light fixtures. You can’t reply casually on the second floor; it’s easy to cause misunderstandings!
Thank you, I’m a graphic designer, and I’m thinking about how to design the circuit traces properly
Also: if they’re all connected together, the neutral wire might need to be thicker than the live wire! 3.2.7 For circuits that meet one of the following conditions, the cross-sectional area of the neutral conductor should be the same as that of the phase conductors: 1 Single-phase two-wire systems ； 2 Three-phase four-wire circuits with copper conductors having a cross-sectional area of 16 mm2 or less, or aluminum conductors having a cross-sectional area of 25 mm2 or less. Items like lighting fixtures that have three wires—live, neutral, and ground—are they part of a single-phase two-wire system?
One distribution box, 20 lighting fixtures – one neutral wire and one ground wire
It’s not appropriate, right? Although a normal neutral wire isn’t live under normal conditions, accidents change things. If you’re a contractor, you might do this to save money, but it’s unnecessary for those who do design work – it only creates risks for themselves
In practice on site, for each circuit with 10 lights, there is a separate supply line for the live wire, the neutral wire, and the ground wire; the lights are connected at the junction box, with each light being connected in parallel to the main live, neutral, and ground wires. For 10 lights, a 3*2.5 cable is generally used, while a 3*4 cable is employed when the length of the wiring is greater.