Would it be proper to tap a 20a circuit at each outlet with a short (6 inch) piece of #14 wire to install a duplex 15a receptacle? I seem to remember a discussion on this before but can't find the code reference. Only thing I find is 210.19(A)(4)(c) and it says "No" Comments please.

240.4(D) restricts #14 to be connected to a 15 amp overcurrent device...

Now, there are exceptions to this rule, but as you pointed out, 210.19(4) exception No. 1(c) spells out the restriction of taps connected to receptacle outlets...

shortcircuit

There is an exception for lamp holders and luminaires but I don't think that extends to a receptacle. Receptacles are the reason for 240.4(D) in the first place IMHO. The installer has no control over what a user does so they build the 80% safety factor into the installation.

Code is pretty blunt in saying that you can't do this with receptacles...you can put 15 amp receptacles on a 20 amp circuit, but you can't pigtail with #14- even though general tap rules would otherwise allow it.

I, for one, do not understand why code denies this practice. Are they trying to prevent the use of cheap 'back-stab' receptacles on 20 amp circuits? Your guess is as good as anyones'.

It would seem reasonable for a single 15a receptacle ... until a cube tap gets plugged in. A duplex would need dual 15a taps. Hence, NO!

In George's question he implied that all of this tap would be inside a box so the hazard is probably not there but it is still a <technical> code violation. If this was simply to pigtail in a receptacle I doubt anyone would ever actually have any problems.