LRod said:

I'm not sure whether the 6-15 is "rated" at 20 amps or not. I know
they are keyed that way. However, on the 120V side, same situation, I
have $1000 that says if you go into your kitchen, where, by code,
there are two 20 amp circuits, you will find nothing but "15 amp
receptacles" (the two vertical bars), even though the plug pattern for
a "20 amp receptacle" is one vertical and one horizontal. The NEMA 20
amp receptacles have a dual slot on one side to accomodate both 15 and
20 amp plugs.

Well, we have 20 amp receptacles in our kitchen as required by local
code. (The obvious giveaway being the T-shaped hot.) As do the 20
amp receptacles in the garage - in addition to the required GFCI
breakers. But I do not deny that most likely, most homes have 15 amp
sockets, 'cause that's what the contractor bought a bulk box of.
Codes vary as do inspectors. ($$$) You may mail my $1000 to:

But as far as the difference between the current capacity of the two,
it *may* make no difference - probably depends of the vendor's
individual design. But the contact area of the socket, it's connector
wiping pattern, and general bulk of the internal conductors makes a
difference. I haven't poured through my copy of the NEC to see what
they "recommend", however. The local inspector told me a 20 amp
circuits required 20 amp rated receptacles - and that's all that
matters to me, because he is the ultimate authority. :-o

The keying is the key, not the current rating. And in any event, why
would it be a problem putting a "15 amp receptacle" on a 20 amp
circuit. NEC would be much more concerned with putting a 20 amp
receptacle on a 15 amp circuit. You don't want to be plugging in
equipment to a 15 amp circuit that is going to draw more than 15 amps.

Because the internal conductor size and blade contact patch inside the
socket determines the ultimate current carrying capacity of the
receptacle. In this bean-counting world, this makes sense to me.
I have noticed that the bonding straps between the two outlets on a
120v 20amp duplex receptacle are heavier than on a 15 amp duplex
receptacle. The socket has to carry as much current as the wiring,
albeit for a much shorter distance. And any non-secure connection
such as a plug and socket is an inherently more resistive connection
than proper in-wall wiring. That is why wall sockets and plugs get
hot before the wiring. Smaller, more resistive connections.

Hey, don't shoot me, I'm only the messenger. ;-)


Greg G.