Is a duplex outlet's max amperage rating for each socket or the whole unit?

If you have a duplex outlet thats rated for lets say 20 amps, is the whole unit rated for 20 amps, or is each socket rated for 20 amps?

Edit: So if I had a circuit that had a 40A breaker on it, could I have 2 devices that both draw a max of 20A on the same duplex outlet?

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migrated from electronics.stackexchange.comMar 7 '12 at 16:45

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Cross posting is generally frowned upon. If one site finds it off-topic they have the ability to migrate it to the site it belongs on. In this case, Home Improvement is the best place for the question. – Kellenjb Mar 7 '12 at 14:14
Please don't cross post the same question to multiple sites. If you get the wrong one your question can (and will) be migrated. – ChrisF Mar 7 '12 at 16:44
Nobody mentioned the possibility that you could break the tabs on the sides of the outlet and feed the top and bottom receptacles from two totally separate 20A circuits. – Craig Jan 19 '15 at 3:47

Each socket can supply up to 20 amps.

However, the total draw of everything on the circuit can also not exceed 20 amps.

Therefore, if you only have one device on the circuit, it can draw up to 20A from any one outlet. However, if you have a 15A device on the circuit, the remaining devices can only draw up to 5A.

Basically, the sum of the current draws for every device on the circuit has to be less then 20A.

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the wire supplying the current and the breaker is rated for 20 amps as well

this means that max current you can draw is 20 amps before the breaker trips but you can draw it all from a single socket if need be

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is correct, you CANNOT draw 40 amps from that outlet. – uncle brad Mar 7 '12 at 11:53
So, restated concisely as a specific answer, each socket is rated for a 20-amp draw. – KeithS Mar 7 '12 at 16:45
The wiring should be rated a lot higher, actually. In Au, common sockets are 10A, the circuit breaker is usually 15A and the wiring is rated to at least 30A. – staticsan Mar 9 '12 at 2:13

Both.

Each receptacle is rated for 20A, and the whole device is rated for 20A.

So you can draw 20A from the top receptacle.

You can draw 20A from the bottom receptacle.

Or any combination less than or equal to 20A.

But you cannot draw more than 20A on any part of the device.

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+1 for images. Looks good and easy to read. – Bob Roberts Feb 21 '13 at 20:14
Really? This seems like a significant safety hazard since 15A duplex receptacles are permitted on 20A circuits. Does this imply that under these circumstances, plugging 2 9A devices into the same receptacle would overload it without tripping the breaker? – dlf Jan 9 at 22:11

The other thing to consider is that residential setups are designed under the assumption that you will never max it out to capacity. For example, you might have 100amp service, yet if you add up the amperage of all the circuit breakers in your house, you'd likely find that the sum exceeds 200amps (100amps per phase, with split phase power in residential = 200amps). Similarily, each 15amp circuit will have multiple outlets capable of drawing 15amps each, even though the circuit is not capable of delivering 15amps to each outlet.

This differs from commercial/industrial where the systems are designed for total loads closer to the breakers' individual ratings, because the electrical systems are designed around the needs of equipment that will usually run all at the same time.

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