no, i wanted JW to answer, that's why I had quoted him. Nothing against you (or him) just wanted his answer.
And as you can see my answer is almost the same as Home's answer just used different words.
When someone asks a question and someone gives the answer most of the time I will remain silent and leave their answer alone but once in a while someone will take personal an answer thus a debate is started between two instead of the forum. I try to keep this from happening by not saying anything when someone else gives the answer therefore I didn't answer directly.
We need to remember that this is a “Do-it-Yourself” type of web site where for the most part the members have no experience or knowledge of electrical theory and installations. The knowledge that most have are old wives tales past down from one to another and in most cases these methods are wrong.
A good case in point is the installation of 20 amp general purpose circuits throughout a home is better than 15 amp circuits. Are these installations compliant? Yes. Are they safer? Not according to the math.
Another is to keep the lights and receptacles on two different circuits so in the event of a breaker tripping one won’t be left in the dark. In 60 years of living I have been left in the dark by a power failure 1000 times for every one time I was left in the dark over a tripped overcurrent device so there is a flaw in that thinking.
What I find most interesting is that when someone points out one of these flaws to the old wives tales most take it personally or as an attack instead of keeping an open mind to the points of views of others especially when the one giving that advice has credentials far above theirs.
As I have pointed out several times in this thread the installation of 20 amp general purpose receptacles is a compliant installation but to think that this circuit somehow gives me more amperage so I can vacuum while watching a DVD on the big screen through the sound around system has flaws.
I like the one where the 20 amp circuits were installed so portable electric heaters could be used. The 20 amp breaker and number 12 conductors in no way change the maximum load that that 15 amp duplex receptacle will handle.
It has been my experience over the years that the receptacle fails and all that wasted natural resource did nothing to prevent the failure.
Ever plug something into a receptacle and the cord cap just fall out? What did we do? Spread the prongs apart a little so it would stay in place?
The receptacle was loaded to the point that the spring metal in the slots have weakened to the point of no grip or the receptacle has failed. No amount of oversizing the conductors and overcurrent device will fix this problem. Upgrading the circuit to 20 amps only causes the failure to happen quicker as we can now put a larger load on that 15 amp receptacle.
This is the facts no matter what someone has told you. This is real world installations that through my career I have personally witnessed as well as many others that I have talked with through my years of experience in the electrical trade.
Then we have those who make the statement that a 15 amp receptacle is rated for 20 amps of feed through. This is true. The metal between the two screws is rated at 20 amps but should someone take the time to take a 15 and 20 amp receptacle apart it is easy to see that the blade slots of the two are a lot different. What we must know is that a 15 amp receptacle even on a 20 amp circuit is rated for 12 amps. The fact that it is on a 20 amp circuit does not change this nor does it change the cord we use to plug in our appliances. The cord is installed by the manufacturer and in most cases will handle a fraction of the amperage of the branch circuit. Up grading the amperage of the circuit then allows more current to flow through these cords. One does not need a formal education to know that the more heat energy allowed to flow through a conductor will allow it to break down faster.
Once again, is it compliant to install 15 amp receptacles on a 20 amp circuit? Yes. Is there more danger when doing this? Yes especially on the general purpose circuits that for the most part are overloaded in the first place.
It is better to install two 15 amp circuits than to install one 20 amp circuit.