Ganged Outlets

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Old 06-04-15, 07:13 PM
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Ganged Outlets

I have searched many posts here and a lot of websites trying to get an answer to a couple of things, but information seems outdated on many websites, so hopefully someone can shed some light on this:

I am wiring an addition, and I have an electrical DIY book that is pretty good, but doesn't always explain the diagrams, and when another diagram seems to conflict, then I wonder if some things are a big deal.

On some circuits there are two outlets in the box, so I have a basic question regarding 'ganged' outlets: 14/2 wire coming into box, black goes to top brass insert (these are back-wire outlets), white goes to the top silver insert. I know it doesn’t matter if I wire the top or bottom outlet, both outlets will get power. But for the jumper wires – let’s say I wire supply into the top outlet, and the jumper wires leave from the bottom outlet – does it matter where those two wires go? Should both jumper wires go to the same outlet (top/bottom)?, or because of the role of the white wire, should the black say, go to the top outlet and the white go to the bottom outlet? I see diagrams in this book I have, like that, and I am wondering if it is a big deal.

Another question regarding ganged outlets which I cannot find a diagram for, so I am wondering if it is possible, and really for any receptacle – if I wire into the outlets from supply, and then, as if I was going to wire another receptacle, the power leaves the box via two other black wires. So a black wire leaving the second outlet, pigtailed to two other wires, going off in separate directions, to say, two other outlets.

And the final question, which I am sorry is so basic, but I cannot really find the answer in the places I have been looking. Diagrams I see always show a ground wire going to the plastic box, under some kind of stove bolt/machine screw I suppose, in addition to the green ground screw on the receptacle. Are both of these really needed?

Thank you so much to anyone who can fill in these answers.
 
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Old 06-04-15, 07:30 PM
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Welcome to the forums.

Using the push in slots on the back of the receptacle is called back stabbing. This method has proven itself as not always reliable. Better to use the side screws.

If you have a single cable coming into the two gang box and you want to install two receptacles.... it's better to take two short pieces of the same size wire and make tails so that each receptacle has a single white and a single black wire connecting it.

If you have multiple cables coming into the box then tie all the whites and add tails and the same for the black wires.

With plastic boxes there is no connection required to the box. Same thing as above with the ground. Add tails to the ground wire so that there is one ground wire per device.
 
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Old 06-04-15, 07:38 PM
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I generally avoid using the backwire terminals--at least the kind where you just poke the wire into a spring loaded contact. They used to be unreliable. May be better now, but old habits.....

But anyway... with two outlets in a double box, when you jumper to the second outlet it doesn't matter whether you use top or bottom terminals or one of each, as long as you keep white and black straight. Sometimes using one of each makes it a little easier to fit everything back in the box, but electrically it's the same.

When you are going to run a second length of romex out of one box to feed another box, you should pigtail the connections rather than use the outlet terminals to make the connections. What this means is: Take the black wire from the feed cable and the black wire from the cable to the second box and wire nut them together along with a short length of black wire that will go to the outlet. Do the same for the white and green/bare wires. (with short white and green/bare wires)

Regarding your third question, when you are using plastic boxes no ground connection to the plastic box is necessary. Connect the ground wire to green terminal on the device and you're done. A ground connection to the box is only needed with metal boxes.
 
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Old 06-07-15, 02:38 PM
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Thank you for the information

So if this image I tried to attach is readable, does this type of splicing effectively take the place of a junction box? Are junction boxes a required thing if going off in 2 directions?

Any maybe one other question: when deciding if a box is big enough for all the wires, how many connectors, or things, get counted for box sizing? I read the list of components which get counted, and deciding what gets counted/not counted I am a little fuzzy on. Is this 7,8,10? or different? I don't think of counting the tails which start and end in the box. Receptacle(s) get counted?

Thank you again.
 
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Old 06-07-15, 02:56 PM
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Effectively what you show is how it gets connected but all splices need to be inside a box. You don't have to have a device in the box. You could have a splice box in the attic or basement that would just be for connections.

You assign each wire, device and clamp a number and then that gets converted to cubic inches.
The following link explains the box fill in detail.
Box Fill Calculations

Basically two cables and a device would fill a standard wall box.
You could also have three cables and a device in an extra deep box.
 
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Old 06-07-15, 03:00 PM
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I butchered your picture, but no need for a new cable to the other receptacle. Just jumper from the other screws on the receptacles themselves within the box.

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Old 06-07-15, 03:03 PM
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What Larry is trying to explain is daisy chaining. One cable in and one cable out per box. Only one cable at the last box. The most popular and effective way to wire.
 
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Old 06-07-15, 03:40 PM
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Thank you for the quick replies. The picture I am trying to show has both of those recept in a double box, not sure if it is extra deep. So a supply romex cable coming in, spiced to two other cables which leave the box to go to other boxes/switches. Also the two outlets get fed in that box. So a total of 3 romex cables (14/2) coming in/going out, plus enough tails for feeding two receptacles.

Following that box sixing link, I count 11 conductors if all five ground wires get counted together as one, which seems to be what that article is saying.
 
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Old 06-07-15, 03:51 PM
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Three xx-2 cables = 6, plus 2 devices = 4, plus 1 ground. Plus any allowance for clamps.
 
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