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I'm planning the circuits for a house right now. I've only done this a couple of times and would like to improve. All of the lighting will be LED recessed lighting so I would like to use one 10A branch circuit per floor. Based on this, there will probably be 5 or 6 home runs for each circuit. What is the cleanest way to handle this?

I was debating getting a triple gang box for each circuit, mounting them in the basement near the breaker panel and using them to break out each circuit. Is there a more clean way of doing this? Something that the inspector won't roll his eyes at?

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    Where on the planet are you? 10A circuit sounds like "Not US/Canada" for a start, where 15A tends to be the smallest 120V breaker you'll normally find. – Ecnerwal Feb 14 '20 at 15:20
  • There's usually no need to have a bush architecture, wherein you split your home run many ways at one point early on. Just split at the first light or switch box where it's necessary, and do that again as needed. Extra boxes look odd, especially when you go to finish the space. That said, the question is too broad for anyone to give you a solid answer. If you'd like to revise to examine a specific scenario, please do. – isherwood Feb 14 '20 at 15:45
  • By the way, I only use the term "home run" for the portion of the circuit that reaches the service panel directly. The incoming power for a light switch branch, for example, usually isn't a home run. – isherwood Feb 14 '20 at 15:54
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    10A breakers exist, certainly - just not common to use since "the breaker protects the wire" and you can't use less than 14Ga wire for distribution under NEC rules, so a 15A breakers protects the minimum distribution wire. Use 10's if it makes you happy. Mixing lighting and receptacles is something I prefer to strictly avoid, having grown up in a house where a fuse (not breaker) blowing would leave you in the dark. Lights on their own rarely if ever overload and cause a trip/blown fuse. – Ecnerwal Feb 14 '20 at 17:12
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    @EdBeal the inspector is entitled to have an opinion on the matter. In that, I agree wholeheartedly. Recep circuits are too prone to trips. I have a place where I have only one conduit run upstairs, and one circuit is GFCI protected for bathroom receps, so only 3 circuits left for everything. I did my level best to have each room's lights on 2 circuits, so if all lights are on, you only lose some. – Harper - Reinstate Monica Feb 14 '20 at 19:52
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First, I gather that gang boxes are what you know, but don't use them. For a nice pile of cubic inches, you can get either 4-11/16" square deep boxes (42 or more cubic inches) or 6" square deep boxes (quite a bit more).

For big boxes like this, go to a proper electrical supply house. Big-box stores actually don't specialize in big boxes, surprisingly; they charge twice normal price when they have them at all.

Hide the hubs behind lights and switches

Other than that, your idea of doing "hub and spokes" is perfectly fine. However, you don't need to bring it all the way down to the basement with a bunch of home runs, you can have 1 or 2 hubs per floor, and conceal the boxes as follows:

  • First, you can get a blank cover plate, and put the box anywhere, although buyers might be annoyed at the electrical cover existing for no reason.
  • Second, you can site it where light switches need to go, and use a 2-gang mud ring, to bring out the usual gang-box form factor you are familiar with. From the outside it will appear to be simple light switches; but behind the switches, it's a major wiring hub in a very big box.

  • Third, you can site it where a surface mount light might go, and get a mud ring giving a 4" ”octagon box" style fitting, i.e. the standard junction box for lighting. Same deal: it looks like a simple light box, but it's actually covering up a large box that is a major splice point.

10A buys you nothing

You think "oh hey, I can use #16 and buy a big panel with my cost savings". Nope. Any wire smaller than 14 AWG is disallowed for mains wiring. It's a lost cause anyway; economies of scale make #14 Romex or THHN so insanely cheap compared to #16 with comparable jacketing that might be legal for in-wall use. You can't just throw some random SJOOW extension cord wire in a wall. You have to follow the rules of one of the Article 300 wiring methods.

You should have a big, big panel, though.

This is the #1 thing we want to communicate to people selecting a service panel. Don't be that oh, so clever guy who says "I need 26 circuits so a 30 space panel will do". (Or worse, a 16 space/32 circuit panel will do; ”circuits" in the double-stuff sense of the word are useless these days). Get PLENTY of extra spaces. Don't even consider less than a 40 space panel for a whole house. 42 is the max before cost climbs dramatically, so if you are at 38 already, don't give up, go with a dual 30. Placing one subpanel cleverly may save you a lot of wire.

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  • Neat! I didn't know that you could hide a large junction box behind a small opening. – Jasen Feb 15 '20 at 8:15
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Given the modern need to provide hot and neutral at each switch box, it's difficult to imagine a home layout where you need 5 or 6 runs back to the electrical panel per floor for a single lighting circuit, rather than just running hot and neutral from the nearest switch box to the next one needing power.

You do need to make sure the boxes are big enough for the wire/device fill. But that's not too difficult. In my personal experience, sometimes a J-box that's just a J-box makes sense (split here and feed 3 things rather than running all the wires through all 3 things), but it's rarely near the electrical panel. Consider that now you are running "5 or 6" wires from "near the panel" to each floor, rather than one wire from the panel to the floor it serves, then breaking it out as needed.

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