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I have a multi-outlet circuit (confirmed that all turn off when I flip the same breaker).

I had always thought the way to find out which was first in the circuit was to remove the one you are guessing is first and see if the others no longer have power. I removed the first one and the other one stayed on. So then I added that first one back in and removed the second one. But the first one kept power!

So I am confused here. Shouldn't one be earlier in the circuit than the other? Or is it possible that they branch in such a way that they are in "parallel" of sorts that they don't rely on each other?

Thank you!

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    What do the wires look like when you remove an outlet? What do they look like with the outlet installed? Show pictures.
    – Hearth
    Mar 4 at 18:25
  • Both outlets include both line and load (two black two white). Installed there are two white on one side and two black on the other. I have reinstalled the original outlets, but if if that information is not sufficient I can pull them back out.
    – evt
    Mar 4 at 18:28
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    It is likely that they are connected in parallel. A picture would help.
    – RussellH
    Mar 4 at 18:40
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    If you are lucky and get the normal cheap/lazy worker, then it is usually the closest outlet to the panel on that circuit that is first. Some crazy money bags wackos out there and put the closest as the last, but they are few and far.
    – crip659
    Mar 4 at 20:22
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    @Armand I don't think most of the meters regular homeowners have are that good to tell for normal house size/outlet spacing. Some of them even change the reading if you look at them funny.
    – crip659
    Mar 4 at 22:48

1 Answer 1

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Tree Topology is required for cabling

A cable is several wires grouped or wrapped in a sheath.

AC mains power requires cabling is done in a Tree Topology. Meaning unlimited branches are permitted, but different branches are not allowed to re-connect to each other, forming a loop. So if you diagrammed your cable diagram in MS-Paint, and used the "paint bucket" tool on any empty space in the canvas, it must fill the entire canvas.

We're in electronics stackexchange, so I'll lede with Why a tree toplogy? Current flows in loops. Electrical codes require that in any cable, current flow be equal and opposite - thus any current which flows up a "branch of the tree" must come back that same branch (not hop to another branch and return via a different route).

Why is "Equal and opposite" required? Because AC power throws a considerable dynamic magnetic field - after all, that's how transformers work. Get it? It's not "a refrigerator magnet" like in DC. It's "a refrigerator magnet that is spinning". As long as wires are grouped, these magnetic fields will substantially cancel each other out. If not, it will induce heating and vibration into nearby metallic things, including the wires themselves. Vibration is a problem because copper and aluminum do not have a fatigue limit so all movement adds to fatigue. The wire cracks, the cross section is reduced so you get localized heating, or it breaks entirely and you get series arcing, making spectacular amounts of heat and starting fires. Indeed North America now mandates Arc Fault Circuit Interruptors (AFCI) which have a digital signal processor "listening" for that "crinkle crunch" of arcing.

Implementation of Tree Topology

Of course... a "vine" is one type of "tree". A very boring one lol.

In some countries, "vine" is used simply because the cheap (50 cent) receptacles provide double terminals (one for "power coming in" and the other for "power going onward"). Of course, the spec grade ($2.50) receptacles provide quad terminals, making tee or plus splits easy.

Use of the receptacle to splice is only a convenience; "pigtail" splices are preferred, and have no limit - one popular splice block has eight ports. Realistically you hit "box fill" limits, but this is Electronics StackExchange, and that's boring LOL.

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