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In a standard wall outlet (two three-prong sockets) do both sockets share power? Say I plugged a surge protector into one and a surge protector into the other and have 5 devices connected to each surge protector. Would that be the same as if I plugged both surge protectors in to one socket using a splitter?

I'm asking because I'm thinking of getting something like this but it only plugs into one socket, where I currently have a surge protector plugged into each socket.

Would this be ok or will it overload the outlet?

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2 Answers 2

It depends. Outlets are manufactured so that both sockets are powered from a single source - one hot wire and one neutral wire and a ground wire for safety.

On almost all outlets, those sockets are connected by small tabs of brass that feeds the connections from one socket to the other. If you attach the hot and neutral wires to the screws for one socket, these brass tabs carry that connection to the other socket. It works the same way if you use the press in connections which are holes on the back of some outlets (but many pros and DIYers do not favor using press in connections). The brass tabs on the side carry the power from one socket to the other.

You can change this. If you break off the brass tab on the hot side, the hot wire you attach to one socket does NOT carry over to the other socket within the outlet. This technique is often used to have an outlet with an always live socket (for clocks, etc,) and a switched outlet (for bedside lamps). The outlet is wired with two separate hot leads, one that is always hot and one that goes through a switch. They could be on the same or different breakers depending on several factors. The neutral side may or may not be connected depending on several factors that are not critical here.

You can also separate the sockets if you wanted a dedicated socket for a high draw device, such as a heater, and run a separate line from the panel. (This generally would require a separate neutral and even a separate ground).

In your example, if the sockets are set up conventionally, that is powered from a single line, there is no difference, except plugging into a socket is a marginally safer approach than multiple splitters. Be sure that the overall load that is likely to be used at one time does not exceed the capacity of the surge protectors or the circuit breaker on the line.

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Your question is full of useful information, most of which does not answer the original question. That's because your answer is on-topic for the site, but the question is off topic! –  Jay Bazuzi Jul 29 '12 at 17:19


The short answer is "probably". We can't be absolutely certain without opening things up a little bit.

You don't have to worry about it too much, though. Plug everything in and try it. If it doesn't flip the breaker* then the in-wall wiring is safe. The only consequence of "overloading the circuit" is tripping the breaker. It that happens, just flip the breaker back on, and find a different solution.

Remember also that many outlets, perhaps in different rooms, can be on the same circuit. You may already have load on this circuit and not know it. So again, just try it & see.

You may be thinking about adding up the load ratings printed on each device and using that to decide if it will overload the circuit. This doesn't work, as devices rarely draw their full rated load. Computer equipment is a great example - my laptop is rated at 90W, but usually draws more like 10W.

*Assuming everything is wired correctly & functioning properly.

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Very good point about multiple outlets sharing a circuit. –  bib Jul 29 '12 at 19:55
+1. Nit pick: if it trips the breaker, step one is to unplug something, then flip the breaker back on. –  BMitch Jul 30 '12 at 0:10
@BMitch is right, especially because when you turn on the breaker, all the devices will turn on at once. Startup load is usually higher than running load, so you are very likely to trip the breaker immediately. So, yes, reduce the load before you turn the breaker back on. –  Jay Bazuzi Jul 30 '12 at 1:23
Sometimes you hear stories of people turning on devices in a very specific order to avoid overloading circuits. –  Jay Bazuzi Jul 30 '12 at 1:23
And you get specialized power strips for computers (not cheap), where they can be configured to power on with a different delay for each outlet. They're not cheap, but quite useful when you have lots of things with motors spinning up (eg, disk drives) –  Joe Jul 30 '12 at 23:43

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