Split receptacle wiring diagram

Top: off · Bottom: on

Flip the switch: the top half follows it, the bottom half never changes. That is the whole reason to break the tab. Tap a conductor to replay the path. The copper highlight is the live path, not a wire colour.

A split receptacle is a duplex outlet with the brass tab broken so its two halves are fed separately. Here the top half runs through a wall switch and the bottom half is fed straight from the supply, so one plug is switched and the other is always live. The silver tab stays intact, so both halves share the one neutral.

Trace it yourself

Two conductors leave the supply on the hot side. Follow the one that goes up into the switch box first: it stops at the switch's common.
The other hot runs along the bottom, straight to the lower brass terminal. No switch. That half is live whenever the breaker is on.
Look at the brass side of the receptacle: the tab between the two brass terminals is broken (the small ✕). The lower hot cannot reach the upper terminal.
Close the switch. The switched hot runs to the upper brass terminal and the top half lights. Open it and only the top half goes dark.
Now the silver side: one neutral arrives at the lower silver terminal, and the intact silver tab carries it to the upper one. Both halves return on it. That is why you break one tab and not the other.

How this circuit works

Two hots arrive at the receptacle: a switched hot for the top and an always-hot for the bottom. Because the brass tab is broken, they do not touch — each feeds only its own half. The neutral tab is left whole, so a single neutral serves both loads on the way back. Flip the switch in the diagram and only the top half responds; the bottom never flinches.

That independence is the whole trick, and it is why the tab exists as a knock-out feature. Snap it and you have two outlets in one yoke; leave it and you have an ordinary duplex.

What goes wrong

The brass tab was never broken

Symptom: the switch does nothing. Both halves are live all the time — and when the switch is on, the switched hot and the always-hot are tied together through the tab.

Everything below is landed exactly as in the correct diagram. The only difference is the tab between the brass terminals, still in one piece.

Top: on · Bottom: on

Flip the switch and watch what changes. Then read why. The copper highlight is the live path, not a wire colour.

Why it behaves like that

The always-hot lands on the lower brass terminal, and the intact tab carries it straight up to the upper one. The top half is now fed from below whether the switch is open or closed, so the switch has nothing to control. Close the switch and its output simply joins a terminal that was already live from the other feed. If the two hots ever came from different circuits, that tab is now bridging them — which is the reason an unbroken tab is more than an inconvenience. The fix is a pair of pliers on the tab; the lesson is to snap it before you land a single wire.

En la obra

The whole job is one tab and two hots. Get the tab right before you land a wire and there is almost nothing left to get wrong; get it wrong and you are taking the device back out with live conductors in the box.

Common mistakes

Breaking the neutral tab too. Only the tab between the brass terminals comes out. Break the silver one as well and the half without a neutral landed on it has no way home.
Snapping the tab after the device is landed. Pliers next to terminated conductors, and the fragment drops into the box. Snap it on the bench, first.
Taking the two hots from unrelated circuits. Someone opens one breaker, sees half the box go dead and assumes the box is dead. Whether the two hots may share a neutral, and what has to disconnect them together, is set by the book — the habit that keeps you alive is that both legs die together.
Leaving the switched conductor unidentified where the book calls for it to be marked. The next person finds two hots and no way to tell which one the switch owns.
Assuming the top half is the switched half. Nothing in the circuit says so. Whichever brass terminal the switched hot lands on is the switched half — decide it, land it, and mark it.

What the inspector looks for

That the brass tab is genuinely broken and the silver tab is genuinely intact. It is the first thing they will look at.
Whether the two hots share one neutral, and if so, the disconnecting arrangement the book requires for that shared return.
The identification the book asks for on the switched conductor, at both ends.
Box fill, with the extra conductor and the extra device counted.
The bond to the device and to the box.

Check it before you call it done

Every breaker feeding the box off. Live-dead-live on both hots, not one.
With nothing landed, read continuity across the two brass terminals. It must read open. If it reads through, the tab is still there — stop and snap it.
Read continuity across the two silver terminals. That one must read through.
Land, energise, and put a tester in the bottom half: live, always, whatever the switch does.
Tester in the top half: it follows the switch and nothing else. With the switch off, read that half — nothing, not a trickle.
Turn the switch on and off five times while watching the bottom half's tester. If it so much as blinks, the tab is bridging the two hots.

Preguntas frecuentes

What is a split receptacle?

A duplex outlet whose two halves have been separated so they can be fed independently. Normally a small metal tab links the two brass terminals into one; snap that tab and each half can be on a different hot — one switched and one always live, or two different circuits.

Which tab do you break — brass or silver?

For the common "top switched, bottom always hot" arrangement you break only the brass (hot-side) tab, so each half takes its own hot, and you leave the silver (neutral-side) tab intact so both halves share the neutral. Breaking the wrong one, or both, changes what the outlet does — the diagram shows the brass tab broken and the silver tab whole.

Why would you switch only half an outlet?

So a lamp plugged into the top half can be controlled by the wall switch while the bottom half stays live for a clock or a charger. It is the tidy way to get a switched plug without giving up the whole receptacle.

Ver también

Duplex receptacle wiring — the same outlet with the tabs left intact.
Single-pole switch wiring — what controls the switched half.
All wiring diagrams

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