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I'm replacing a the middle outlet/receptacle on a non-GFCI circuit with two receptacles and I can't for the life of me figure out why the neutral wires are swapped on the middle receptacle. It appears to be deliberate as the 12 ga wire is bent to create a criss-cross pattern. This was installed by a DIY-er so to me this would seem deliberate. The tabs aren't broken so it doesn't look like this would really affect anything. I've attached a screenshot to show the original configuration.

Wiring diagram

(Please ignore the lack of ground in the diagram, everything is properly grounded with a third wire throughout.)

What would be a benefit / reason behind swapping the neutrals?

Context: 120V power from a pure-sine-wave inverter.

Machavity
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Aaron_H
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5 Answers5

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It makes no difference, perhaps it was more convenient for the person wiring it up. Or they got it connected on Neutral, and changed their minds about which side was going to be up before wiring Hot.

Regardless, it makes no difference - there is no "line and load" on a non GFCI outlet - if the tabs are unbroken, both screws on a side are the same.

Ecnerwal
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  • Thanks, having re-wired it back up I can sorta see how the wiring may have been more convenient (or they even just got it mixed up not realizing which screw was from which wire). – Aaron_H Jan 06 '22 at 03:13
  • Line can matter for an outlet. If a device has a fuse to protect itself and you wire the outlet backwards, the fuse may not work appropriately. You can get a simple outlet tester at a hardware store to see if you've wired the outlet backwards. – Ben Jan 06 '22 at 13:19
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    That would be hot & neutral, not line & load. – Ecnerwal Jan 06 '22 at 13:59
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Note "Line" refers to a wire pair of both hot and neutral.

There's no such thing as Line and Load on plain outlets

They're all "Line".

The screws and the brass strip they attached to are visibly, obviously directly connected. Therefore they are the same exact thing, and obviously don't have a different function in any way. Thus, they are interchangeable, and it doesn't matter.

It's a common confusion to use the word "Line" for the supply power line coming from the breaker, and "Load" to describe the onward wires carrying power to other points-of-use. I strongly recommend against this choice of wordage. It will create nothing but confusion.

Those terms are used for active components like GFCIs and smart switches, which do something significant to the power, causing the "Load" output to be basically different in character. That is why you should reserve the terms for that use, and not for any other.

For instance, there is a material question anytime you install a GFCI receptacle as to whether the onward lines should be attached to "Line" or "Load". But to have that conversation, you need the vocabulary to do so!

Harper - Reinstate Monica
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  • Line can matter for an outlet. If a device has a fuse to protect itself and you wire the outlet backwards, the fuse may not work appropriately. You can get a simple outlet tester at a hardware store to see if you've wired the outlet backwards. I do agree however, that it would be better to use the word neutral to describe the other wire. – Ben Jan 06 '22 at 13:17
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    @Ben You’re confused. “Line vs. load” that the OP is asking about refers to pairs (or even triples) of wires: supply vs. downstream. You’re talking about *polarity* i.e. swapping line and neutral wires within a pair. Load is not an alternate word for neutral. – nobody Jan 06 '22 at 14:11
  • @Ben This isn't about wiring an outlet backwards. Here, "line" means incoming hot and "load" means outgoing hot. They're both hot. The "neutral" is something completely different. – David Schwartz Jan 06 '22 at 17:33
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    @Ben understandable confusion. I added a bit at the top. – Harper - Reinstate Monica Jan 07 '22 at 18:49
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As Ecnerwal already pointed out, it doesn't matter at all. One way to think about it is that there is an alternative way of wiring this receptacle:

  • Use a wire nut to connect the two neutral wires together with a short white wire and connect that short wire to either screw (doesn't matter which one).
  • Use a wire nut to connect the two hot wires together with a short black (or red or blue or yellow) wire and connect that short wire to either screw (doesn't matter which one).

That is functionally the same - the electrons don't care.

In fact, I suspect the only reason there are two screws on each side is to allow splitting by removing the tabs. It is cheaper for manufacturers, retailers and electricians to use one SKU that includes two screws on each side and a removable tab than to have three SKUs (one with one screw on each side, one with two screws on each side not connected, one with two screws on the hot side not connected and one screw on the neutral side). When not split you can use just top, just bottom or both. You can't actually put two wires on one screw...well, actually you can (without using a pigtail) if you use a better quality ("commercial grade") which lets you put wires straight in under a small metal piece, which gets held down when the screw is tightened, rather than looping around the screw.

manassehkatz-Moving 2 Codidact
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  • Makes sense, I just wanted to confirm that it didn't have something to do with the contact area for that amount of current. Then again electrons just take the shortest path anyways so it doesn't really matter. – Aaron_H Jan 06 '22 at 03:12
  • Not an issue of contact area, **however**, you should avoid "backstab" connections due to many problems (including contact area!) and if you use regular screw connections (as opposed to screw-clamp where the wire goes in straight and easy) then you need to make sure the wire has a good clean right-sized "hook" under the screw for good contact. – manassehkatz-Moving 2 Codidact Jan 06 '22 at 03:15
  • Line can matter for an outlet. If a device has a fuse to protect itself and you wire the outlet backwards, the fuse may not work appropriately. You can get a simple outlet tester at a hardware store to see if you've wired the outlet backwards. – Ben Jan 06 '22 at 13:19
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    @Ben The reference of "line" here is not *hot*. It refers to both hot & neutral on "from panel" vs. "ongoing to other devices". As far as wiring "backwards", any fuse should still work just fine - on AC you can't even tell the difference between hot & neutral by itself (only with respect to ground) and even on DC a *fuse* just cares about amount of current, it doesn't care about polarity. But there are safety issues with hot/neutral reversed because switches are normally on *hot* and a reversed connection could lead to unexpected exposed live hot wires. – manassehkatz-Moving 2 Codidact Jan 06 '22 at 13:28
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    Aside from manufacturing concerns, it would be rather inconvenient for electricians to have to carry around separate tab and non-tab receptacles. – nobody Jan 06 '22 at 14:13
  • @manassehkatz-Moving2Codidact, On both AC and DC you can tell the difference between the polarity because if you put your fuse on the neutral side of your circuit, the circuit will stay energized after the fuse is blown which can lead to catastrophic failure. I understand that your meter and for that matter your oscilloscope can't tell, but a short in a device can. I understand that the fuse will still work, but please don't wire things backwards "because it doesn't matter". The device that doesn't blow up could be in your own home. – Ben Jan 07 '22 at 18:06
  • @Ben The issue here is *not* "hot vs. neutral". Indeed, fuse/breaker is on the hot side and if put on the neutral side instead there can be serious (dangerous) problems. The issue here is whether or not "line vs. load" matters, and the answer is that it does *not* matter for simple AC wiring, only matters when GFCI is in between. – manassehkatz-Moving 2 Codidact Jan 07 '22 at 18:19
  • @manassehkatz-Moving2Codidact, I think I'm seeing some additional confusion. I'm not talking about a fuse to protect the wire. I'm talking about a fuse inside a device that is plugged into the outlet. Something like the little fuses that go into christmas lights. You might notice that the plugs on some things have prongs that are the same size and some that don't. The ones that don't are meant to plug in a certain way because they are designed to not fail catastrophically and cause a dangerous problem like you just described. It's the same thing on a smaller scale, but can still cause a fire. – Ben Jan 07 '22 at 18:56
  • @Ben That's "the other end" of "hot vs. neutral", and I agree with that. But again, the issue raised by OP is about "which neutral screw", **not** about "hot vs. neutral". – manassehkatz-Moving 2 Codidact Jan 07 '22 at 19:17
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After terminating the neutrals the installer twisted/flipped the device to screw down the lives keeping the screwdriver in their dominant hand, causing the neutral wires to cross. If the bend of the wires appears deliberate, that may be because they were manipulated after the fact to help them fit inside the junction box or for a neat appearance.

jay613
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Even though this is an acceptable way to wire grouped outlets (in the same box), the tab is not intended as a pass through for outlets in a string of separated outlets as it is a failure point and makes trouble shooting difficult. It used to be common to connect both feed and pass wires under the same screw but pigtailing with wire nuts is now the norm. The tab is a breakable tab for the purpose of having a switched outlet or alternate power source, and the reason for the availability of the second screw.

Cristina Vekos
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    Welcome to DIY. "the tab is not intended as a pass through" why do say this? In fact they are even rated higher, at 20A for a 15A receptacle, precisely to allow it as a pass through by a 15A receptacle on a 15A and 20A circuit. – P2000 Jan 07 '22 at 04:57
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    If the outlet happens to have been wired in using pig-tails, the _only_ way for power to get from one outlet to the other is the tab, yet you're saying it's not designed for this? Do you have some code reference? Nobody said anything about connecting 2 wires under one screw (which is not allowed in most cases), though they do make receptacles now with side clamps designed for 2 wires. – FreeMan Jan 07 '22 at 12:48
  • @FreeMan I think OP means a pigtail with three wires total, one for the circuit, one for the pigtail to this receptacle, and one to "continue" the circuit out to other outlets. In other words, wiring in parallel rather than sequence. In that case, the tab is not relevant for 'passing' power on to the next outlet down the line; if the outlet dies, it doesn't kill anything else further down the circuit. – TylerH Jan 07 '22 at 21:39
  • I will say when I re-wired it, I did it the conventional way (both the source wires were on top and the onward wires were on bottom). I appreciate the input - I'm not too worried, there are only two receptacles on this circuit. – Aaron_H Jan 08 '22 at 18:25