Preferred method for wiring 2 gang box?

[piratius]

Hey guys - I asked this in my garage build thread, but I'm going to copy/paste it here too, because it'll get the advice of people who are more in the know on the electrical side of things.

First off, I've done a fair amount of standard plug/switch replacement, and even added a few circuits (and yes, they all passed inspection ). However, I'm going to be adding a TON of receptacles and stuff in the shop, and I have a question about technique for wiring new 2-gang boxes. The way I see it, there are two ways to do it, and I didn't know if inspectors preferred one way vs the other. I did a quick look through the Virginia Code, and couldn't seem to find anything except for the maximum number of wires per box.

First, the "neat & tidy way" which has the least number of wires and nuts in the box - feed the 12/2 Romex into one side of the 2 gang box, and go directly into the first plug. Leave the safety ground wire extra long, connected to the receptacle with a pigtail hanging off. Then use short (6"? 8"?) White/Black jumpers from the first outlet to go to the second outlet in the box. Then, wire the outgoing 12/2 (that goes to the next box down the wall) to the second outlet (the same way you did the first - with a long-ish safety ground pigtail). Use a wire nut and join the two safety grounds. With that method, there are a total of 8 wires and 1 wire nut in the box.

Second, the "traditional way" - feed the 12/2 Romex into the 2 gang box. Feed the outgoing 12/2 wire into the box. Cut a pair of pigtails from 12/2. Join all 4 white wires with a nut, all 4 black wires with a nut, all 4 safety grounds with a nut, and then simply connect the outlets as normal. You have 12 wires and 3 wire nuts in the box. This is the way all of the outlets and switches in my house (built in 1968!) were done, even though they're single-gang boxes!

Opinions?

 

[Spyider]

i don't see how it would matter as long as its done safely. or just call your local inspector and just ask him..

 

[JPinSTL]

I'm not a legal sparky, but my buddy who helped me wire my shop is. I just got scolded for doing it the 1st way. My thinking was the same, more tidy. But by jumpering the 2nd receptacle from the 1st you are not maintaining the continuity of the conductor. The load of the 2nd is now flowing though the 1st. If you had two high draw devices you could overload the 1st receptacle. Some of the cheaper receptacles just have a small thin tab to handle that current. Much better to have supply the incoming power to each receptacle individually with its own pigtail.

He also said in a residential shop where you are working alone, the chance of overloading any 2 adjacent receptacles was slim.

 

[wyliesdiesels]

U could use green wire nuts with the hole in the end and have one less ground wire in the box.

 

[ABSTIFFGS]

I'm also not an electrician but have always preferred to pigtail everything.

 

[wyliesdiesels]

I'm not a legal sparky, but my buddy who helped me wire my shop is. I just got scolded for doing it the 1st way. My thinking was the same, more tidy. But by jumpering the 2nd receptacle from the 1st you are not maintaining the continuity of the conductor. The load of the 2nd is now flowing though the 1st. If you had two high draw devices you could overload the 1st receptacle. Some of the cheaper receptacles just have a small thin tab to handle that current. Much better to have supply the incoming power to each receptacle individually with its own pigtail.

He also said in a residential shop where you are working alone, the chance of overloading any 2 adjacent receptacles was slim.

Old wives tale. Total cockamame.

There is no code prohibition against wiring outlets that way.

Now yes it would be better to wire with pigtails in the case if one receptacle failed the others would continue to work.

However the tab u speak of is rated for 15a or 20a to flow through it.

Or u could use spec grade back-wired outlets with 4 holes per side and then the current wouldnt even flow through the tab if both wires were placed under the same screw pressure plate.

Also in regards to what u said about using 2 high draw pieces of equipemnt- if the outlet is properly breakered at 15a or 20a, which the tab on the outlet is rated to handle and UL listed for, then both pieces of equipment's combined draw cant be over the breaker rating otherwise the breaker would trip. So how would the first receptacle be overload when both cant pull more than the breaker rating?

That info u were given is NOT logical.

 

[sberry]

It really doesnt go thru the receptacle.

 

[alfredeneuman]

To make up a 2 gang box with NO splices:

Leave at least a foot of conductor out of the box.
At least 3" out the box, strip about an inch or so of insulation from the wire with a knife but do not cut the wire.

Wrap the stripped wire around the terminal of the device until the end of the wire is headed directly away from the device. There should be at least 6" of wire left.

Strip the end off of the remaining wire and wire the 2nd device as you normally would.

(It's actually easier to do than explain)

 

[Marctrees]

And, of course, everybody hooks and screws, NOT the lazy push in hole option.

Never, nowhere. Stupid. Marc

 

[Junkman]

I used 12 gauge wire, and 20 amp receptacles 30 plus years ago, and some were back stabbed, and others were put around the screws, and neither has failed. I believe that the quality/brand of the receptacles makes a big difference in a back stabbed installation success or failure.

 

[zmaxmotorsports]

I stick with the traditional myself.

 

[piratius]

Guys, thanks for all the opinions - I never knew this would be such a hot topic, and we all need to remember to keep grounded!

Ok, now that the groaning is over, I'll put in a quick call to the electrician who did the sub panel and see what his local experience says. I have to do a huge mess with a 4-gang light-switch box, so I went ahead and bought some of the big wire nuts that'll hold 5 14ga wires, and the only package they had was for 100 of the suckers (at $8 it wasn't too painful either, even if I only use a dozen of them). That way, if he says that I need to use the wire nut method, I'm covered and I already have the materials.

As for my outlets, like WyliesDiesels said, they're all "spec grade" 20A receptacles, with the 4 holes on the back for the screw plates, so even if a receptacle fails (or the little tab on the side fails) current will still flow downstream. I'm over-wiring the whole shop, all of the circuits are 20A with 20A breakers and 12AWG wire, when I made do with two 15A circuits in the old shop.

I'm tempted to wire one wall one way, and the other wall the other way, and see which method I like better. Do you think that would annoy the inspector?

 

[larry4406]

I used metal quad boxes so I could put two receptacles in each box. I ran two separate 20A circuits using 12/2 romex from the panel to a quad box where it was easy access and would not be blocked by machines or storage (adjacent the garage door for me). At this first quad box, I installed the GFI's. Then I daisy chained the remaining outlets keeping the left and right circuits separate and coordinated to their respective GFI's. I used the screw terminals on the outlets to create the feed in and feed out (no jumpers or stabs). The hot and neutrals for the separate circuits were kept separate in the quad boxes but the grounds were connected.

The breakers for these circuits are side by side in the panel. I have not handle tied them, but think this might be appropriate since when working on an open quad box, one circuit could be hot while other is off unless one tripped both breakers.

 

[CJ7VFR]

To make up a 2 gang box with NO splices:

Leave at least a foot of conductor out of the box.
At least 3" out the box, strip about an inch or so of insulation from the wire with a knife but do not cut the wire.

Wrap the stripped wire around the terminal of the device until the end of the wire is headed directly away from the device. There should be at least 6" of wire left.

Strip the end off of the remaining wire and wire the 2nd device as you normally would.

(It's actually easier to do than explain)

The house I live in was built in 1955. Over the years there were upgrades to it, such as increasing the amperage in the house and adding new lights, receptacles and what not.

I can tell that an old time electrician did a lot of the work because almost every "always on" receptacle that I have replaced (not because it failed or was bad, but because my wife changed the color of the room and she wanted receptacles and switches that were not just white or black) they were all wired like you said.

The wires enter the box and if they continue on to power something else downstream of that box, the wires were not cut, but left intact. About a 1 inch section of the insulation was removed from the wires, the bare part of the wire bent into a "U" shape, and then the wire was attached to the receptacle under the screws.

The first time I saw this I was like what the hell? Then I asked a friend of mine who is an electrician, and he said they did that all the time years ago, and not many electricians do it anymore because it takes more time to do it that way.

Jim

 

[theoldwizard1]

Second, the "traditional way" - feed the 12/2 Romex into the 2 gang box. Feed the outgoing 12/2 wire into the box. Cut a pair of pigtails from 12/2. Join all 4 white wires with a nut, all 4 black wires with a nut, all 4 safety grounds with a nut, and then simply connect the outlets as normal. You have 12 wires and 3 wire nuts in the box. This is the way all of the outlets and switches in my house (built in 1968!) were done, even though they're single-gang boxes!

Must be a new "tradition" because I have NEVER seen that is any house built in the 40s or 50s !

I would say "traditional" is, leave all wire long coming in the box. About 6" from the clamp, bare the insulation on the black and white wire. Loop all 3 wires around the appropriate screw and tighten. Run the wires over to the second outlet making sure to leave enough slack. If this is in the middle of a chain, repeat the previous and the take the free end and wire nut it to the cable leaving the box.

 

[theoldwizard1]

... but because my wife changed the color of the room and she wanted receptacles and switches that were not just white or black ...

Been there, done that !

... he said they did that all the time years ago, and not many electricians do it anymore because it takes more time to do it that way.

**** job for the apprentice : connect pigtail to all the outlets. Might be faster but it will cost more in material especially if you are doing a whole house.

 

[piratius]

**** job for the apprentice : connect pigtail to all the outlets. Might be faster but it will cost more in material especially if you are doing a whole house.

That all boils down to a time vs money situation. Any 120V box with pigtails will have 3 wire nuts. A baggie of 100 wire nuts is $8 at the local Home Depot/Lowes. Assume it takes 5 minutes per outlet to strip/loop/screw the old fashioned way. If using wire nuts shaves just ONE minute off per box (Cut/strip/screw) then the electrician has saved 30 minutes of his time over 33 outlets. If you're doing a whole house with 60 outlets/switches/etc, then you're saving a whole hour of your time! I know electricians bill more than $16/hour (what 66 receptacles worth of wire nuts costs) - so in the long run, he's making money by being able to complete the job quicker, and go do something else.

My house, built in 1968, uses a combination of wire nuts and back-stabbed daisy chaining, depending on the room - almost like they had two or more electricians working on it. One did the lights and switches, the other did all the outlets. Every time I find a back stabbed outlet (usually as we paint) I make a point to replace it with a back wired screw terminal type.

 

[zmaxmotorsports]

Must be a new "tradition" because I have NEVER seen that is any house built in the 40s or 50s !

I would say "traditional" is, leave all wire long coming in the box. About 6" from the clamp, bare the insulation on the black and white wire. Loop all 3 wires around the appropriate screw and tighten. Run the wires over to the second outlet making sure to leave enough slack. If this is in the middle of a chain, repeat the previous and the take the free end and wire nut it to the cable leaving the box.

Different areas have different traditions I guess. I prefer a separate pigtail to each outlet or switch,easier/safer to work on each device in my book anyway.

 

[Radix2]

IMO the best way is to buy the better outlets with the straight wire clamps and use the outlets to jump from. The screw down clamps are better than wire nuts and you also cut down on the box fill, don't see any downside.

 

[piratius]

IMO the best way is to buy the better outlets with the straight wire clamps and use the outlets to jump from. The screw down clamps are better than wire nuts and you also cut down on the box fill, don't see any downside.

Those are the outlets I bought, so I'm hoping that everything goes smoothly - I'd like to use this method, should hopefully be quick & easy!

 

[jetnow1]

I was taught to always use a pigtail so if an outlet failed the outlets further down the
line would not also be effected. Yes it takes a little more time, but every electrical inspector I have seen is happy with it.

 

[jives]

This thread is timely. I just finished setting up my boxes for receptacles by using pigtails on all three wires (black, white, ground). My son stopped by to check it out and said that's not the way they did it. They used method #1 the OP listed. So, I did some internet checking and his way #1 is in series and will leave all downstream receptacles non-functioning if an upstream receptacle fails. My way, #2 in the OP, is in parallel and will leave all receptacles functioning downstream.

Question, though. The first receptacle is a GFI and should be wired in series, correct?

 

[Gttrucker]

I like to put a gfi on the 1st outlet of each branch and then it protects all the outlets. Not required by code, but nice extra protection. GFIs have helped me identify equipment that's having trouble long before it burned up.
You can get them in 20amp water and dust/tamper resistant versions for about $20.
In the case of a gfi, you have to run power through it (your example 1) for it to protect down line outlets, but you can wire the rest any way you want.