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How to know the different circuit breakers

 

Easy tips to help you find your way around inside your home's electrical panel

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

Why do so many so-called electricians "forget" to label circuits in electrical panel boxes? For that matter, why do they also "forget" to install a convenience light fixture above the panel, so you can see the breakers in the first place?

These are just two of the many mysteries of figuring out electrical circuits. Homeowners have been befuddled by breakers since the time when breakers were fuses. So many wires! So many circuits. Where do they go? Finding answers to which circuit breakers do what can be frustrating, but it's certainly within the abilities of most people. Think of it as a Treasure Hunt. Just remember...

WORKING INSIDE AN OPEN, LIVE ELECTRICAL PANEL CAN BE FATAL.

Instructions
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.


photo by Eli Duke
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

photo by

Types of Breakers

  • Main: At the top of panel
  • Single Pole: Fills one space
  • Double Pole: Fills two spaces
  • GFCI Breaker: Shock protection
  • Mini-Twin: Two breakers, one slot

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Comments (1 to 10 of 10)

Jim Bessey
Nov 11, 10 at 03:38 AM
Thanks for dropping in, Mark; I'm honored. Sounds like you might need to do more than just "identify" those breakers, huh? Our house was built in the 60s and had all sorts of weird electrical oddities. Most of them are gone now, because I'm scared of "bad electric" and the whole FIRE issue. BTW, Mark, you aren't trying to run all those big Helium Servers off a cord in your garage, are you?? -big grin-
Mark Ranalli
Nov 10, 10 at 09:51 PM
Great guide Jim. I need to do this at my house. The home was built in 1920, and we're tripping the breakers all the time.
Jim Bessey
Oct 25, 10 at 01:31 AM
Thanks so much for your electrifying feedback, Kevin! :-)
Kevin W Byrom
Oct 24, 10 at 02:39 PM
Great guide, Jim! I've been in the process of upgrading my home that was built in 1959, and the way things were wired in my attic alone are "shocking" to say the least. On today's standards many things in my home are substandard, but I'm bringing everything up to code myself.

Everything you've written here, I actually did when I first bought my home; great job!

Jim Bessey
May 11, 10 at 10:22 PM
Big thanks to Glory, Kimberly, and Olivia for stopping by and taking the time to Comment. I struggled with this one, picturing some hapless soul digging around next to live buss bars. Not the kind of "buzz" I'd ever want to promote!
Olivia Bredbenner
Mar 27, 10 at 04:26 PM
Great site Jim..sure helpful guide for those that need reinforced Ed. and safety precautions.
Kimberly Schiller
Feb 11, 10 at 04:41 PM
Nice job Jim. Best line - Kill the power,not yourself! Humor is a great way to help people remember not to be idiots :)
Glory Lennon
Feb 09, 10 at 04:29 PM
Amazing guide, Jim. Makes me think even I can tackle this...on second thought, I'll let Tommy do it! Great job.
Jim Bessey
Jan 07, 10 at 02:54 AM
Thanks very much, Raven. I've sent you a message in reply. What you describe is fairly dangerous, unless you are thoroughly familiar with working on electrical systems. It's also a pretty reasonable service call for any qualified electrician.
Raven Lebeau
Jan 06, 10 at 11:02 PM
Very thorough, but down-to-earth-- nice work! Are you going to make a how-to guide about replacing a faulty circuit breaker? If you try to flip a circuit breaker and it immediately flips back, it means it needs to be replaced, right? (I ask because we've had no electricity in our spare bedroom for the past few months... that's the kind of lazy homeowners my husband and I are.) Anyway, I could use a good how-to guide on replacing a circuit breaker.
Jim Bessey
Helium member since Aug 20, 07
Number of Guides: 4
+ Post your Question|> See All Q&A
Before you submit your question Log-in or Register.
Hi Jim: Do you recommend any kind of labels for identification of individual circuit breakers?
most panel boxes come with pre-formatted labels, Raymond. Not many electricians bother to use them,...

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