Wow, five minute response time. Thanks for the quick help!

If you use the screws on the receptacles to continue the circuit, the small link between the sets on each side has the same cross section as a #12 wire.

It is only when there is a single receptacle on a 20 A circuit it must be a 20 A receptacle.
A duplex receptacle counts as two receptacles.

They make a 15amp receptacle for a 15 amp breaker and a 20 amp receptacle for a 20 amp breaker. Yes you should of used all 20 amp receptacles.. Even tho the plugs are daisy chained that does not mater. The amperage rating is for the receptacle only. You will only get 15 amps out of a 15 amp receptacle period even tho its on a 20 amp breaker. Its really not that big of a deal so dont worry about it to much. Tho I would run the treadmill alone on the 20 amp receptacle to be safe. You got 5 more amps to work with in case you decide to plug in a radio or whatever. 12/2 is exactly what you needed for the 20 amp circuit. You will be fine.

Two things jump out at me "I went quick and easy and used the screws to hold the wire in with the push-in end technique so they're wired in series"

If I read it correctly, you used the push in/backstab method for one set of wires, then used the screws to hold the wires downstream? As I understand it, that's a code violation. Using the screws is the preferred technique but you should use pigtails to the outlet, then the other end is connected to the feed and the downstream. My other qualm is "they're wired in series" - if you really mean series, active-neutral-active-neutral, you will be dividing a single 120 voltage between each outlet, so for each device plugged in the voltage will drop more. I presume/hope you meant PARALLEL, ie active-active, neutral-neutral etc.

I'm not quibbling, you don't want to get your terms mixed up.

FWIW, it is uncommon to use a 20 AMP receptacle in residential wiring. Frankly there's no reason to install one unless you have something with a 20 AMP plug on it.

The NEC allows either 15 or 20 AMP receptacles on a 20 AMP circuit and UL lists them to be used this way.

Although not in every case, the difference in receptacles is often just the slots in the front cover.

You would use them as dedicated receptacles for like a music room or garage. Power tools/amps/etc. Also other than the extra little slot on the 20amp the other difference is 5more amps..

electricman, listen to unclebill, bus driver, and brickeyee. They have it right. There is nothing about the typical receptacle to differentiate 15A from 20A except the slots that admit the plug.

pjb, pigtailing is one acceptable way. In most jurisdictions putting the incoming and outgoing wires under the screws is also acceptable, except for the neutral on multiwire branch circuits. I know of a jurisdiction where they have apparently extended the requirement to pigtail to all receptacles.

"They make a 15amp receptacle for a 15 amp breaker and a 20 amp receptacle for a 20 amp breaker. Yes you should of used all 20 amp receptacles.

Unless the OP is in Canada this is completely wrong. If there is at least one DUPLEX receptacle you can use 15A receptacles on a 20A circuit.

Even tho the plugs are daisy chained that does not mater. The amperage rating is for the receptacle only.

NO, the amperage rating is for EACH of the TWO receptacles in a duplex device. The whole device is still rated for 20A feed-through.

You will only get 15 amps out of a 15 amp receptacle period even tho its on a 20 amp breaker.

Once again, 15A per receptacle. A 15A duplex is TWO 15A receptacles on one yoke.

Also other than the extra little slot on the 20amp the other difference is 5more amps..

5 more amps of WHAT???

I didnt say you could not use a 15a receptacle on a 20amp branch. I said I would of used all 20 amp plugs. 5 more amps of WHAT???? The receptacle is rated for 5 more amp to be pulled from whatever is plugged into it!! Its rated for 20amps...

So you are saying a 20amp plug is 20 amps as a whole (the duplex) or 20amps for the upper and 20 amps for the lower? Im confused here.

"So you are saying a 20amp plug is 20 amps as a whole (the duplex) or 20amps for the upper and 20 amps for the lower?"

Yes, and yes.

"You will only get 15 amps out of a 15 amp receptacle period even tho its on a 20 amp breaker. "

Um... with a 20 amp breaker you can pull up to 20 amps out of that receptacle.

A receptacle has no means of limiting the current draw on it, other than failure or the overcurrent protection device tripping - thus the reason we are required to install circuit breakers...

"Now what happens when we break the metal tab between the 2 screws and install a 20 amp feed on the top, and an additional 20 amp feed on the bottom..."

I think i know this one, is it 220? Or 2 20s.

It would be 120 and still 20 amps. There is no such thing as 110 its 120 just as there is no 220 its 240.. Unless you have some voltage drop going on or something of that nature. lol I see where u are going with that tho. What I was tring to say tho was technically you can not get 20 amps from each plug at the same time. That is impossible. The duplex is only good for 20 amps, so 10 up top and 10 down below and its maxed out.., or 20 on just on plug from the duplex.. Right? Im making this way to confusing.....

That was a joke, sorry you didn't get it.

"The duplex is only good for 20 amps, so 10 up top and 10 down below and its maxed out.., or 20 on just on plug from the duplex.."

You're right but it has nothing to do with the duplex and everything to do with the circuit breaker.

It's still not right. A 20A duplex receptacle can deliver 20A on either of it's sockets. The 20A is the aggregate you maximum you can draw at any distinct time without blowing the breaker.

"A 20A duplex receptacle can deliver 20A on either of it's sockets. The 20A is the aggregate you maximum you can draw at any distinct time without blowing the breaker."

Or 40A aggregate if you're using a split duplex receptacle with a DP breaker.

"What I was tring to say tho was technically you can not get 20 amps from each plug at the same time. That is impossible. The duplex is only good for 20 amps"

Yes you can get 20 amps from each outlet at the same time. The upper and lower receptacle are connected by the metal tabs on the side of the outlet, cut those metal tabs and now you can install a 20 amp circuit on the top, and a 20 amp circuit on the bottom recpetacle. By doing this one could now run their 20 amp saw from the top receptacle, and their 20 amp heater from the bottom recepetacle.

This is exactly why it is called a "duplex receptacle" as others have mentioned. It is called a "duplex" because it has (2) 20 amp receptacles on it.

OK, so bottom line is I can have either 15 or 20A outlets on the 20A circuit with 12-2 wire, depending on my draw needs for each outlet location? I didn't mean to cause a ruckus. My other thread seems to be a bit more contested. Heh.