question about installation of 20 amp wall plug

My guess is you miswired it. Sounds like maybe you had Hot and Ground reversed. Putting a 20amp wall plug on a 15 amp line shouldn't be a problem (you are limited to the 15 amp breaker).

You either miswired it or you have the wires touching each other. Pull the outlet back out and check it. The green wire goes to the ground screw. The white wire normally goes to the outlets on the same side as the ground wire. The black wire normally goes on the other side. Are all of the screws tightened down?

You should not use a 20A receptacle on a 15A circuit, regardless of what the audio retailers say. This is not allowed by the NEC. There is the potential for longterm overloading of the 15A circuit.

A typical household circuit breaker will trip in the presence of either a bolted fault (i.e., dead short) or large overcurrent, depending on amount of that overcurrent.

The maximum continuous/longterm current draw allowed on a 15A circuit is 12A or 80%. When you install a 20A receptacle, there is the increased potential for longterm current draw to be as much as 100% to 110%, depending on the trip curve of the breaker, yet not have it trip. That is the reason for the prohibition ny the NEC.

Please see the receptacle ratings table in NEC Article 210.

http://img.villagephotos.com/p/2003-5/191557/Receptacle_Ratings_Table.jpg

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