Why does an outlet need so many wires?

[shortylickens]

Builder grade. Been in house 17 years. Finally tired of the plug working only sometimes. Decide to replace it.
I pull the thing out and it has three hot, three cold, and two grounds.

What the crap for?
I know it aint a switched plug. And my new one has the ability to take all eight wires.

I just wanna know why.



For reference this outlet sits right next to the electronically controlled gas fireplace, but doesnt seem to interact with it in any manner.

 

[MagnusTheBrewer]

Separate circuits in the same outlet.

 

[Yakk]

Those are usually commercial duplexes with separate circuits for each plug. Residential usually have multiple duplexes on the same circuit.

Good stuff, as long as the the wires are not combined later on...

 

[NutBucket]

They daisy chain the wiring. Power in and power out. Been doing it that way for for decades.

 

[Humpy]

More wires equal more power!

It doesn't look like the tab is broken off to split the outlet to two circuits or a switched outlet. I also thought (don't know for sure) that you could only daisy chain one wire in and one wire out, any more requires a pig tail from a nutted connection?

 

[Paperdoc]

I can see the reason, but I think it was done poorly. In fact, where I live, it definitely does NOT meet code in one respect, and it has one obvious bad connection.

First, the good news, with a little note of caution. In the foreground between the two screws for Black wires (Hot side) the brass tab that normally is there to link the upper and lower connection points has been broken off. This has converted the device into what's called a "Split Duplex" receptacle, as opposed to "plain Duplex". That is, the upper and lower halves of the outlet fixture are actually fed completely separately from each other from separate breakers in the box downstairs. So, EACH outlet half can support a load of 15 amps, assuming the wiring is 14 gauge and each breaker is 15 amp rated. The "note of caution" is that usually this is done using a single 14/3 (plus Ground) cable with Black AND Red wires for Hots, and White Neutral, and that cable is fed from a DUPLEX breaker in the panel. The important point here is that such a breaker is designed to cut off BOTH Hot lines at the same time, so a breaker in the "off" position leaves NO live Hot wire inside this outlet box. Since this particular job was done with two separate 14/2 cables from the breaker box, we cannot tell whether they used the proper DUPLEX breaker, or just two normal single breakers.

Now, looking closely we can see that two Black Hot leads are pushed into the two holes in the back on the Hot side, and two White Neutral leads into the holes on the other side. The outlet device is designed for use this way, so it certainly does meet code there. Personally, especially on outlets that might see larger loads, I prefer to use the screw terminals and ensure a really solid electrical connection, and avoid the push-in holes. But that is my preference, not a code requirement.

Here's where I question whether code has been followed. In my area, one is NEVER allowed to use the terminals of an outlet device to make junctions of conductors. ALL such junctions need to be made using proper wire joint items like twist-on nuts or compression fittings, and the resulting junctions folded into the back of the wall box. Those junctions can include short (6" to 8") leads that come out to the terminals on the outlet device. In the photo posted by OP, it is clear that a third cable of 14/2 (plus Ground) wires has been brought into this box and connected to ONE of the two power supply cables by using the screw terminals on the outlet device. AND, even WORSE: look closely at the top screw in the foreground to which one Black Hot lead is attached. It is NOT tightened down on that wire!! That connection is just loosely wrapped part way around the screw! We can't see how the matching White third wire was done on the other side.

 

[Humpy]

The tab is still there.

I had assumed the OP had loosened the screw terminal himself, but if not then that's the obvious explanation for the receptacle only working some of the time.

 

[JEDIYoda]

It needs so many wires in order to work properly!

 

[boomerang]

And my new one has the ability to take all eight wires.

Not all will accept a wire. Four are for wires and the adjacent openings are provided to release the wire. A pointed tool is inserted to release the tension which allows the wire to be removed.

 

[highland145]

Not all will accept a wire. Four are for wires and the adjacent openings are provided to release the wire. A pointed tool is inserted to release the tension which allows the wire to be removed.

giggity

 

[NetWareHead]

Not a fan at all of stab in terminals. I always use screw terminals. If I have as many wires as shown in this box, I pigtail so only one set of wires connects to the outlet

 

[ivwshane]

Not a fan at all of stab in terminals. I always use screw terminals. If I have as many wires as shown in this box, I pigtail so only one set of wires connects to the outlet

Pigtail with a lead wire coming from each bundle up the outlet?

 

[NutBucket]

If you buy the "pro" grade outlets then the stab-in terminals are actually clamp down via the normal screws on the side. Those are what I like

 

[NetWareHead]

Pigtail with a lead wire coming from each bundle up the outlet?

Pretty much. I don't like to use the actual outlet and put it in series with the rest of the load. If the outlet fails, everything downstream also dies.

 

[mindless1]

^ If the outlet fails in a way that prevents downstream power, it would have to burn (melt) through that brass, something that's not going to happen unless there is an overload downstream, then if for some reason your fuse or breaker doesn't trip as it should, then you'd rather that burnt through instead of continuing to have overload after it. This is assuming copper wire, not aluminum, and the screws properly tightened.

In other words it's more a matter of having correctly (or higher) rated outlets and fuses or breakers not rated higher than the outlets. 3 runs in that outlet box, with nuts and another wire to the outlet... have fun getting all that stuffed back into the box. If it was all done at time of construction, I'd sooner put a junction box next to it.

If you buy the "pro" grade outlets then the stab-in terminals are actually clamp down via the normal screws on the side. Those are what I like

That appears to be what the pictured outlet does, with 4 usable holes for hot, and for common, 2nd hole not being a spring release.

 

[NutBucket]

Correction, the replacement that the OP bought has that design

 

[NetWareHead]

^ If the outlet fails in a way that prevents downstream power, it would have to burn (melt) through that brass, something that's not going to happen unless there is an overload downstream, then if for some reason your fuse or breaker doesn't trip as it should, then you'd rather that burnt through instead of continuing to have overload after it. This is assuming copper wire, not aluminum, and the screws properly tightened.

In other words it's more a matter of having correctly (or higher) rated outlets and fuses or breakers not rated higher than the outlets. 3 runs in that outlet box, with nuts and another wire to the outlet... have fun getting all that stuffed back into the box. If it was all done at time of construction, I'd sooner put a junction box next to it.

Whats do either copper or aluminum have to do with it? Aluminum wiring's more stringent splicing requirements aside, if the wire is rated for ampacity of the circuit and properly spliced/connected, it should be fine.

Also Ive had outlets fail due to physical damage to the receptacle and cut power to the rest of the string downstream. And as careful as we are to tighten the terminals properly, sometimes you get one that loosens and fails the circuit. Water damage could also cause outlet failure. Have seen it in restaurants; careless employees using too much water to wash the wall around an outlet. Water drips inside the box and shorts the terminals to the box.

I know its not a code issue (at least near me) for reason to pigtail vs feed through, but I just like doing it that way. I have been called particular more than once before. Not sure what you mean by put a junction box next to it. All boxes have to be accessible and cant be buried in walls. Since I like to pigtail, I tend to use extra deep boxes where appropriate to give me room. For splicing together grounds, I use crimps rather than wire nuts. One less wire nut in the box saves space and makes it easier to stuff the wires back in.

I disagree with putting in higher rated outlets in the room connected to lower rated wires. That just permits someone to plug in equipment not rated for the circuit. E.g. a 15 amp circuit with nema 5-20 receptacle rather than nema 5-15 will allow a heavy draw appliance like an air conditioner rated for 20 amps to plug into and load this circuit past its capacity. I have done the opposite and used a 20 amp breaker and sent 12 gauge wire to a room to connect a string of 15 amp outlets.

 

[mindless1]

Whats do either copper or aluminum have to do with it? Aluminum wiring's more stringent splicing requirements aside, if the wire is rated for ampacity of the circuit and properly spliced/connected, it should be fine.

Not necessarily fine using the same outlet when you have aluminum both under the screw and in the terminal holes. This makes aluminum wire creep, oxidation, and dissimilar metal corrosion more problematic.

Also Ive had outlets fail due to physical damage to the receptacle and cut power to the rest of the string downstream. And as careful as we are to tighten the terminals properly, sometimes you get one that loosens and fails the circuit. Water damage could also cause outlet failure. Have seen it in restaurants; careless employees using too much water to wash the wall around an outlet. Water drips inside the box and shorts the terminals to the box.

It is a rare fault where an outlet failure cuts power downstream, unless you're talking about a ground fault circuit and that would usually trip downstream if the GFC outlet is upstream instead of every outlet. That's not an issue of box wiring, it's one of having shared the GFC.

I know its not a code issue (at least near me) for reason to pigtail vs feed through, but I just like doing it that way. I have been called particular more than once before. Not sure what you mean by put a junction box next to it. All boxes have to be accessible and cant be buried in walls. Since I like to pigtail, I tend to use extra deep boxes where appropriate to give me room. For splicing together grounds, I use crimps rather than wire nuts. One less wire nut in the box saves space and makes it easier to stuff the wires back in.

If the wall is finished on both sides then you can put a wall plate on it, or just use a double wide and put a switch in for the outlet with everyone whining about fantom power draw these days. Usually the homeowner wasn't present to tell the electrician to use extra deep boxes, and if the homeowner is that into it, would probably not want three runs into one outlet box. It may be that this was a DIY addition after the fact.

I disagree with putting in higher rated outlets in the room connected to lower rated wires. That just permits someone to plug in equipment not rated for the circuit. E.g. a 15 amp circuit with nema 5-20 receptacle rather than nema 5-15 will allow a heavy draw appliance like an air conditioner rated for 20 amps to plug into and load this circuit past its capacity. I have done the opposite and used a 20 amp breaker and sent 12 gauge wire to a room to connect a string of 15 amp outlets.

I never stated using lower rated wires, nor did I mean using a different outlet blade configuration. Obviously you wouldn't plug a 20A AC into a 15A circuit. Daisy chaining runs through the outlets is a pretty common practice, possibly more often done than not.

 

[NetWareHead]

Not necessarily fine using the same outlet when you have aluminum both under the screw and in the terminal holes. This makes aluminum wire creep, oxidation, and dissimilar metal corrosion more problematic.

Agree. Terminal holes (assuming this to be the stab-in connectors?) are/were the source of many aluminum wiring fires. The springs let go eventually and cause arcing and heat and possibly a fire. I dont like stab in with copper and they are more dangerous with softer aluminum.

Aluminum in a screw terminal is much better but still subject to strict installation procedure. Anti-ox paste applied between the wire and mating surfaces, wrapping the wire in proper direction to form an eye around the screw and a properly torqued screw are whats needed to ensure a safe connection that doesnt heat up. If today an aluminum wiring job has lasted for several decades in an older house, it must have been built right when installed or was brought up to standards previously, or it would have never lasted this long. A very good example of shit in = shit out. Anyway this point about aluminum wiring is becoming more and more moot as time passes and it gets ripped out and replaced with copper.

It is a rare fault where an outlet failure cuts power downstream, unless you're talking about a ground fault circuit and that would usually trip downstream if the GFC outlet is upstream instead of every outlet. That's not an issue of box wiring, it's one of having shared the GFC.

No I dont think it is that rare, I just replaced an 2 separate receptacles this year that caused everything downstream to die off in 2 different rental units. Stab in connectors eventually let go and disconnected the hot wire. They were all wired with the feed through method that places the receptacles in series with the rest of the circuit. As soon as the wiring was repaired and outlet replaced, the remaining outlets downstream had power again. Like the old christmas lights where one dies, everything else does too. In a gfci outlet, you dont pigtail that, it is deliberately wired in series with the rest of the circuit so the gfci trip can deaden everything downstream. Unless you want only that one outlet gfci location protected and nothing else downstream.

If the wall is finished on both sides then you can put a wall plate on it, or just use a double wide and put a switch in for the outlet with everyone whining about fantom power draw these days. Usually the homeowner wasn't present to tell the electrician to use extra deep boxes, and if the homeowner is that into it, would probably not want three runs into one outlet box. It may be that this was a DIY addition after the fact.

Point taken about a typical homeowner not being that into it and deeper boxes are more rare. I recognize that I am a bit particular and want my wiring done rather specifically. For the same reason I abhor handy-boxes and almost never use them. Just too small and not enough cubic inches for more than 1-2 wires.