Electrical Question - Adding an outlet

[Midwest]

I need to add an outlet to an existing circuit taking power from another outlet.  Circuit is 20 amp.

The existing outlet has power coming in and going out at the screw terminals.  Do a) I attach the new circuit to the push terminals in back, b) attach 2 sets of wires to the outgoing screw terminals or c) wire it it using a short piece of wire and wire nuts and before it gets to the outlet?

So far I've used method c to put in the box.  It was tight getting back in.  If method c is correct do I need a bigger box?

Thanks for any help in advance.

MW

[Chris22]

B. 

C works as well, but is needlessly complex and cumbersome to shove into the box, as you saw.

[Midwest]

It looks like the outlet to the left now.  I need to add a third outlet off the outlet to the left.

[Chris22]

Then it's wire nut time.

[zolotiyeruki]

There's an alternative, actually--run the wire from the new outlet to the existing outlet.  On that wire, strip the ends, but then also strip a 1" section about 5-6" from the end, so your wire kinda looks like this:  (comes out of wall) =========------==============------ (end)
the === are insulated sections, the ---- are uninsulated sections.  Do it for both the line (usually black) and neutral (white) wires.

Disconnect the right-hand outlet from the current-left-hand outlet.  Use the uninsulated section in the middle of the new wire to wrap around the screws on the old left-hand outlet.  Then use a wire nut to connect the ends of these wires to the ends of the wires coming from the right-hand outlet.  You'll still need wire nuts, but you'll only have to put two wires into each.

You didn't mention anything about grounds, but make sure those are connected as well.

Thanks, Chris22, for providing a drawing to riff off.

[cockersx3]

Agree with previous poster - just splice off one of the wires and run the wiring to the new outlet.

Only part I didn't follow was about the "push fit connectors."  Are you sure this is a 20A circuit?  I've never seen a push-fit connector designed for a 20A outlet - I've only seen them on 15A outlets and they only fit 14 gauge wire.  Probably want to make sure you're not putting a 15A outlet into a 20A circuit, which is against code I think. 

[zolotiyeruki]

Agree with previous poster - just splice off one of the wires and run the wiring to the new outlet.

Only part I didn't follow was about the "push fit connectors."  Are you sure this is a 20A circuit?  I've never seen a push-fit connector designed for a 20A outlet - I've only seen them on 15A outlets and they only fit 14 gauge wire.  Probably want to make sure you're not putting a 15A outlet into a 20A circuit, which is against code I think.

Actually, it's totally ok to put a 15A outlet on 12AWG wire and a 20A breaker.  The reason is that a load which draws >15A actually has a different-shaped plug that only fits in 20A-rated outlets.  Those 20A outlets are the ones where one of the slots looks like a sideways T, like this:

In such a situation, the protection comes from the shape of the outlet, not the breaker.

[BudgetSlasher]

Agree with previous poster - just splice off one of the wires and run the wiring to the new outlet.

Only part I didn't follow was about the "push fit connectors."  Are you sure this is a 20A circuit?  I've never seen a push-fit connector designed for a 20A outlet - I've only seen them on 15A outlets and they only fit 14 gauge wire.  Probably want to make sure you're not putting a 15A outlet into a 20A circuit, which is against code I think.

Actually, it's totally ok to put a 15A outlet on 12AWG wire and a 20A breaker.  The reason is that a load which draws >15A actually has a different-shaped plug that only fits in 20A-rated outlets.  Those 20A outlets are the ones where one of the slots looks like a sideways T, like this:

In such a situation, the protection comes from the shape of the outlet, not the breaker.

You are mostly . . . correct. When I wired my workshop I looked into this and is it perfectly fine to place 15 amp outlets on a 12 gauge / 20 amp circuit provided, but I believe there must be multiple outlets on the circuit to allow a 15 amp outlet on a 20 amp circuit (or stated another way a 15 amp outlet cannot be on the only outlet on a 20 amp cirucit).

[paddedhat]

Push wiring is a garbage way to do any kind of wiring. The poster who commented about not being able to push wire #12 conductors is partially correct,  code changes eliminated new receptacles that accommodate #12 in the rear slots, however they were prevalent in the past.

Fifteen amp receptacles on 20 amp. circuits are fine, and legal. Twenty amp. plugs and the need for 20 amp outlets to connect them to are pretty unusual. Tools and appliances that come with 20 amp. plugs are usually seen in things like commercial kitchens, and on professional grade shop tools. 
When it comes to splicing, wire nuts and "Tails" or short piece of wire going to the outlet are the gold standard. The secret is to carefully shape everything into the back of the box before attempting to get the receptacle in.

[Midwest]

These are 15 amp on a 20 amp circuit.  I had used a pigtail, but it was tight getting it back in.  There is an art to this stuff and I'm not an artist yet.  Wanted to make sure I had done it correctly and up to code.  If there was better way, I was going to redo but sounds like I just need to practice being neat on pushing the wires back in.

Thanks to all.

MW

[sokoloff]

National code doesn't require pigtails, but some local codes (California) do.

IMO, using pigtails is the safest and therefore most proper way to go; I would never daisy chain through the "second" screw or use the "stab in" terminals, even on 14ga/15A circuits.

[Chris22]

IMO, using pigtails is the safest and therefore most proper way to go; I would never daisy chain through the "second" screw or use the "stab in" terminals, even on 14ga/15A circuits.

Why?  Agree on the stab-ins, but I've never had a second screw connection come loose, but have plenty of wire nuts come off. 

[FarmerPete]

IMO, using pigtails is the safest and therefore most proper way to go; I would never daisy chain through the "second" screw or use the "stab in" terminals, even on 14ga/15A circuits.

Why?  Agree on the stab-ins, but I've never had a second screw connection come loose, but have plenty of wire nuts come off.

If the outlet goes bad, everything down chain will potentially fail.  Pigtails will avoid this.

Doing the pigtails is the best way to do it.  Code will tell you what the connector fill rate is on your boxes.  You can look that info up online to know if you need a bigger box or not.  In general, if you got it back in, it's fine.

[sokoloff]

IMO, using pigtails is the safest and therefore most proper way to go; I would never daisy chain through the "second" screw or use the "stab in" terminals, even on 14ga/15A circuits.

Why?  Agree on the stab-ins, but I've never had a second screw connection come loose, but have plenty of wire nuts come off.

Have to admit that the source is mostly the way I was I taught, but I can see uneven heating (one conductor carrying no current) causing uneven stress on the screws and working it in the plastic. Arcing (from loose connections) is a much greater fire risk than a completely disconnected connection. Screw terminals that are loose seem to have more chance to arc than wirenuts, especially since you have more screw terminals "in circuit and under load" in a daisy-chain of screws than in the pigtail arrangement.

I've never seen a properly sized and properly tightened wirenut come off. (Thumb-tight for a weakling is not properly tightened.)

[BudgetSlasher]

IMO, using pigtails is the safest and therefore most proper way to go; I would never daisy chain through the "second" screw or use the "stab in" terminals, even on 14ga/15A circuits.

Why?  Agree on the stab-ins, but I've never had a second screw connection come loose, but have plenty of wire nuts come off.

If the outlet goes bad, everything down chain will potentially fail.  Pigtails will avoid this.

Doing the pigtails is the best way to do it.  Code will tell you what the connector fill rate is on your boxes.  You can look that info up online to know if you need a bigger box or not.  In general, if you got it back in, it's fine.

The connection between the 2 screw is exterior to the inner workings of the outlet; a small metal plate is under each screw with a small tab connecting the two, even if the outlet failed that tab would maintain a connection between the wires.

That is broken with a screw driver or pair of pliers when you want the two outlets in the duplex to be on different circuits, such as when you want one outlet always hot and the other switched. I highly doubt there is any way for that tab to be broken while installed . . . at least were you would feel safe using the downstream outlets.