How to know the different circuit breakers



Tracing circuits and identifying breakers: Amp-plify your wiring knowledge
Step 1

Before you begin: Turn off sensitive electronics

Before you start flipping breakers off and on again, turn off your computer and any other electronics that might be affected by sudden power outages.

Also turn off heavy power users like room air conditioners, high-wattage lights, and the washer and dryer.

Step 2

Provide a light source at your electrical panel

No sense fumbling around dangerous current in the dark. It’s also much easier to label the circuits you identify, if you can see what you’re writing.

Step 3

It’s best to work with a helper, if possible

You can use a radio, or even rig up something tricky with a baby monitor; but it’s much easier to track down your home’s circuits with a friend on the other end. One of you will flip breakers while the other takes note of what happens.

Step 4

Open the panel door, not the panel cover

DO NOT WORK INSIDE AN OPEN, LIVE ELECTRICAL PANEL

Yes, professional electricians do it all the time. Unless you know exactly what you’re doing, don’t do it. Just open the panel door so you can see all the pretty breakers. Don’t remove the cover.

What if your panel cover is already off, or it’s loose on the box? That’s what we in the business call …

AN UNSAFE WORKING CONDITION

Unless you’re a pro, get some help and properly secure your panel’s safety cover before making ANY attempt to identify electrical circuits.

Step 5

Familiarize yourself with the breakers inside

See «Types of Breakers» in red, at right

You should see a large breaker at the top of the panel, numbered between 80 and 200 amperes: this is your Main breaker, and should be clearly labeled. Leave this one alone.

Most of the breakers you see should be Single Pole, rated at either 15-amp or 20-amp. Each of these will be about the size of a deck of cards viewed from the smallest side.

You should also see one, two, or three Double Pole breakers, rated from 30 to 50 amperes. If any breakers are labeled, these are the likely candidates. They might provide power to:

  • Electric Dryer
  • Electic oven and/or cookstove
  • A sub-panel
  • Central Air, or pool pump
  • Other heavy equipment

You also may find one or two GFCI breakers, which have yellow TEST buttons. These will look different from all the other breakers, and are usually mounted near the bottom of the panel.

Step 6

Start small and work your way up

Find out what your 15-amp breakers do, first. Using a friend as a spotter, turn off one breaker at a time. These breakers should control lights, non-kitchen outlets, or both. Try to discover light circuits first, and then note which outlets go off with which lights. Use a radio for that.

If you’re working alone, plug a radio into a bedroom outlet. Turn it on and up loud enough to hear from your panel’s location. Then, trip breakers until you hear the radio stop. Repeat as needed until you have all non-kitchen outlets identified.

Note that some of these might control GAS-fired appliances, including your furnace.

Step 7

Track down the 20-amp circuits next

Expect each of these heavier-load breakers to control:

  • All kitchen outlets (older homes) -or-
  • One or a pair of kitchen outlets (modern)
  • Specific appliances, like a Microwave
  • Room-size air conditioners
  • Workshop outlets
  • Garage outlet(s)

Test for these as you did the 15-amp circuits. Without a helper, you’ll have to do a fair amount of back-n-forth checking. Some appliances will beep when you turn them off/on; that helps.

If you see one or more GFCI breakers, those might protect a bathroom or outdoor outlets — usually more than one for older homes.

Step 8

Figure out what’s left

At this point you should have identified nearly all the circuits. Most often, specialty circuits have been labeled.

If larger, Double Pole breakers aren’t marked, take the time to figure these out now. Check your electric dryer, furnace, range, or cooktop and oven.

If you have one or more Sub-Panels, these should be fed using the same type of breaker; but they should be marked. Secondary panels might control:

  • Central Air
  • Pool or Spa
  • Workshop added later on
  • Specialty equipment, almost always marked
Step 9

Label all circuits and close panel door

Before you call the job done, make sure you’ve labeled all the breakers. Also make certain that all circuits are back on. Close the panel door behind you.

You’ll have some clock-fixing and other resetting to do on electronics. Be sure to thank your helper. And next time you need to turn the power off in one place or another, you’ll know exactly which breaker to trip. Won’t that be nice?


You will Need
• Light and/or flashlight
• A helper -or-
• A radio
• Patience

Tips & Warnings
• Respect the power of electricity
• Turn off sensitive electronics before working
• Use extreme caution around open panel cover
• Kill the power, not yourself —
• Shut off Main Breaker for open panel
• Never work inside a «live» panel
• Do not «up-amp» circuit breakers

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