said by Mike Rios:a 20 amp receptacle ( simplex or duplex ) can ONLY be used if it's a dedicated outlet, and it cannot share with other chained outlets as per NEC, so having 15 amp outlets on a 20 amp circuits is ok and normal per NEC. I never wired any outlet pass through, but junction the wires inside the junction box and then pigtail out to the receptacle ( as long as you have the volume requirement per NEC article 370-27(b) ). This way failure of an outlet is local and does not affect the parallel chain. In any result all 15amp outlets are UL listed for 20 amp pass through ( side screw terminals ), in case you do want to chain through and outlet, but you can only backstab #14 ( rated for 15 amps )to any given 15amp outlet , 20's do not have backstab as it only side wired.
I didn't realize that 15 amp outlets could handle 20 amp pass-thrus. That's good to know. Still... I don't trust what's been done in this house. The previous owners did alot of work themselves - including the addition of those two rooms, and the wiring up of the outlets. Given the number of electrical issues I've encountered, I took no chances.
I could fill several pages of posts with stories of what I've found. I can't tell you how many times I've uttered the phrase "WHAT were they smoking?!" Quick non-electrical related story. Right after we moved in (this was in the dead of summer) I noticed a black mark on our lawn - a spot about 6 - 8 inches across. Figuring that it was after the 4th of July someone set off some firework that singed my lawn. I cut it, and the black grass was largely gone... until the next week when it showed up again. I started thinking we were in an episode of the X-files or something.
Talking with a neighbor I found out the cause. The previous owner took it upon himself to change his own oil. And dispose of it too - in his yard. My neighbor stopped by one time, and his leg sunk up to his shin in a pool of oil and dirt.
Everytime I uncover something in this house I scratch my head - like when I pulled up the carpet in my daughters room and found tile. A 2x2 foot square of ceramic tile cemented to the subflooring. With no discernable purpose. Baffled the hell out of me. No, the room was never a bathroom (I've had folks make that guess before), and it was built by those same owners.
