How to map every circuit in your house by yourself

Find out which breaker controls what, in an afternoon or two, with your phone, its charger, and some tape.

Updated: September 2026

The card inside the panel door is wrong

Most panel cards are partly right, and partly right is more dangerous than blank. They hold just enough handwriting to look useful: a few room names, several entries that just say “lights”, and notes from people who no longer live in the house. Renovations happen, circuits change, and the card stays where it was. You find out how wrong it is at the worst moment, standing in a dark room with a screwdriver in your hand, walking back to the basement to try the next breaker.

The job is to replace that card with a record you made yourself. A house is mapped when every breaker has a list of what it controls, and every outlet, light and appliance you care about names the breaker it runs on. Not a guess and not an inheritance: something you checked.

Two facts make it a smaller job than it sounds. Cut a breaker and every light on it goes dark at once, so the lights answer for free, an area at a time. And the slow part is never the testing, it is the walk back to the panel, so the plan below is built around making one trip per breaker.

How long it takes depends on two things you can check before you start: how many breakers are on the panel, and how far that panel is from the rooms. A single floor with eighteen breakers and the panel in the garage is an afternoon for the whole thing. Three floors with forty breakers and the panel in the basement is more like two. Either way each pass ends with a map that is already useful, so stopping partway costs you nothing.

If someone can stay at the panel while you walk, use the two-person guide instead. It covers the complete job with one person flipping breakers and one recording the map.

What you need

• Your phone. The app runs in a browser, including next to the panel, and it is where you record what you see as you see it.
• Masking tape and a marker. This is for numbering the panel, and it is not optional. Painter’s tape peels too easily to trust for years on a panel door.
• Your charger. Plug the phone in at each outlet: if it starts charging, that socket is still live. You already have both, so there is nothing to buy. A plug-in nightlight or a lamp with a short cord does the same job if you would rather not keep unplugging the phone.
• Optional: an outlet tester, sometimes sold as a receptacle tester, for about ten dollars. It is the size of a plug and does two jobs at one stop: its lights go out with the breaker, and the pattern they show reads the wiring in that socket. Useful, not required. Everything in this guide works with the phone and charger you are already carrying.

You do not need a ladder, a screwdriver, or a voltage pen. You do not need to open anything.

No electrical experience needed. Mapping is turning breakers off and recording what stopped working.

You do not need to remove the panel cover to use Circuit Mapper. Turn off one breaker at a time. If anything looks wrong, stop and call an electrician. Outlet testers and voltage testers are useful checks, not proof that work is safe.

Before you touch the panel

Most of the typing happens before you flip a single breaker, and none of it needs the power off.

Walk the house room by room and add the rooms, then what is in each one: the outlets, the ceiling lights, the switches, the dishwasher, the garage door opener. Include the easy-to-forget things, the doorbell transformer, the smoke alarms, the outdoor outlets, the furnace, when you can identify them without opening anything. Ten minutes a room is normal, and the second room is faster than the first. Give each thing a name that locates it: “west wall by the desk” beats “outlet 2”, and it will still beat it in two years when you have forgotten which one you meant.

Then the panel. Add every breaker: its amperage, whether it takes one slot or two, whether it has a TEST button or other visible protection, whether it is a spare. Record what you can read from the closed panel and leave the rest as unknown. Guessing only creates another card that looks more certain than it is. You do not type the slot numbers, because the app lays the slots out the way a panel is actually wired, odd down the left and even down the right.

Then number the panel itself

Do not skip this step: everything else depends on it. Run a strip of tape down each side of the switches and write each slot’s number on the tape beside it, copying from the layout the app shows you.

Number the slots, not just the switches. A double-pole breaker takes two numbered slots. A tandem breaker puts two circuits in one numbered slot. An empty slot keeps its number so the positions below it do not shift.

Do not copy the numbers off the card on the door. Panels interleave odd numbers down the left and even numbers down the right, often with the main breaker taking up space in the middle, so the card’s rows frequently do not sit beside the switch they name. Counting from the top is wrong more often than it is right.

Here is the test for whether you have done it well enough. Could someone who has never been in your house flip breaker 5, on the first try, without asking you? Could that same person find the west-wall outlet in the back bedroom from the name you gave it? Solo, you will lose track without the numbers. And the day you do have a second pair of hands, the person at the panel knows nothing about your house and has only the number to go on.

First pass: lights, because they answer for free

Cut a breaker and every light on it dies at once, visibly. You do not have to be near them. An outlet, on the other hand, shows you nothing at all and needs a different approach to testing.

So do the lights as their own pass, over one area at a time: a floor, or a few rooms you can walk in a loop. The app narrows the walk to the area and the kind of device you chose, so you are not scanning the whole house on every breaker.

Switch every light in the area on before you go to the panel. A light that was already off looks exactly like a light with no power, and if you record that as a miss you will never notice. The app lists the lights in your chosen area before the walk starts, with the switch that operates each one where you have recorded it, so the list is something to read rather than something else to remember.

Then the loop, which is the whole pass:

1. At the panel, turn off the breaker the app names. It works through the panel in order and skips the ones you have already done in this pass.
2. Walk the area and mark what went dark.
3. Back to the panel, turn it on, and the app names the next one.

You can see most of the answers from across the room, and for most lights that is enough. Where you are standing at one, work the switch rather than trusting what you saw from the doorway. Nothing happens and you have found its breaker. It lights and you have not. If a bulb might be dead, or you cannot get a clear look, mark it Unsure and move on. A dead bulb reads exactly like a dead circuit, and Unsure is the honest record of that.

At the end of the pass the app tells you which lights never went dark on any breaker: “These never went dark on any breaker. Check the switch and the bulb, then walk them again.” That is almost always a switch that was off or a bulb that has gone, and it is much cheaper to find out at the end of the afternoon than in two years.

Second pass: outlets and the hardwired things

This is the slower half, because an outlet gives you nothing to watch. You bring the evidence with you.

Plug the phone in at each socket: look for the charging indicator, unplug, move to the next one. Whatever you carry, make sure you know it works. If it has not shown you a single live socket yet, you are testing the indicator, not the circuit.

Some sockets map themselves for free. Anything already plugged in and lit counts: the standby light on the TV, the clock on the microwave, the router’s blinking lights, the coffee maker’s display. Note what is already there before you start unplugging things to make room.

Finish everything you can reach on the current breaker before you walk back to the panel. The plugging is not the slow part. The trips up and down the stairs are, and every one you avoid is a few minutes back.

Two things worth knowing while you are down at the sockets:

• Test both plugs of a kitchen counter outlet. The top and bottom halves of the same outlet are sometimes fed by different breakers, which is common above a counter. Plug into both, record both, and treat them as two.
• If you are using an outlet tester, one stop does both jobs. Tell the app you are testing with a tester and each outlet gets a place to record what the lights showed, alongside which breaker it turned out to be on. You are already crouched there, so you may as well take both readings.

The GFCI shortcut

If a socket has TEST and RESET buttons on it, you have a shortcut. GFCI outlets usually sit at the start of a run and feed several ordinary outlets downstream of them, which is common in bathrooms, kitchens, garages and outside walls. Press TEST and everything downstream loses power without you going anywhere near the panel. Walk the area, note what died, then press RESET to bring it back.

That gives you the group in one move. You still need one breaker trip to find out which breaker the whole group is on, which is one trip instead of five. Before you press TEST, look at what might be on that circuit: a freezer in the garage or anything with a clock will not enjoy it, and RESET afterwards is not optional.

Dishwashers, furnaces and the rest

Permanently wired loads have nothing to plug into: the dishwasher, the furnace, the water heater, the garage door opener, the range hood. Watch the thing itself if it can be running safely while you work, since a dishwasher that stops mid-cycle or a furnace fan that spins down is as clear a signal as a light going out. Failing that, use a light or a socket near it that you have already mapped, and treat the answer as likely rather than proven.

If getting a clear answer would mean removing a cover, touching wiring, or putting something into a state it should not be in, stop. Mark it Unsure and leave it for another day or an electrician. A map with one honest unknown is better than a finished-looking map with a guess in it.

Think for a moment before cutting a breaker that might feed the fridge, the freezer, the sump pump, the furnace or the router. You turn those off in this pass, and once the map is done you never have to guess at them again. Turn each breaker back on as soon as its walk is finished.

When the map disagrees with you

Sooner or later a device will go dark on a breaker that is not the one you recorded for it earlier. That is either a real wiring quirk or a mistake in the earlier session, and there is no way for the app to tell which. So it does not try. It shows you the answer you gave before and the one you just got, and asks which is right, with the option to keep the old one, change to the new one, or leave it for now and decide later. Nothing gets overwritten quietly, and if the same disagreement keeps coming back, it is a good thing to have written down the next time an electrician is in the house.

Print it and tape it inside the door

Print the breaker list, also called a panel schedule, and tape it inside the panel door. That paper is the copy for whoever opens the panel next, including you at eleven at night when the phone is upstairs.

The app stays the real record. It is searchable, it syncs to your account so the map is on your phone at the panel and on your computer at the desk, and when you add a circuit or move an appliance you update it and print the card again instead of crossing something out.

And “done” is not all or nothing. Partial is the normal state of a map like this, and the app shows counts rather than a progress bar, because there is no prize for finishing. Three breakers in, you already know more than the card told you. A finished lighting pass is useful on its own. The outlets can wait for the next rainy afternoon.