DIY Disaster Doctor: Short Circuits


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Kevin Hawes of Assured Home Inspections in Calgary, Alberta (via The Money Pit). Used with permission of the ASHI Reporter.

This rudimentary labeling pretty much sums up the homeowner’s knowledge of which circuit breaker powers what. It should be an electrifying experience if there’s ever an emergency here!

Diagnosis: Obviously, we’re witnessing an extreme lack of knowledge about electrical panels, which house the circuit breakers (and sometimes, fuses) that protect your home’s electrical components (everything from your doorbell to your water heater) from dangerous power surges, which can lead to fires. Proper labeling of circuit breakers or fuses is imperative for easy identification in an emergency, an outage isolated to one area of the house, or a strategic electrical shutdown before leaving home for a trip or other extended absence.

Rx: Learn what circuit breaker powers what appliance, light fixture, etc. in your electrical panel well before an emergency strikes, and you’ll save time while preventing dangerous electrical errors.

There are two approaches for determining which switch corresponds to which component. You can either take inventory of every component of your house that uses electricity (from the power grid, obviously not battery- or solar-powered devices) and shut the switches off one by one, checking which component loses power each time. Or you can work in reverse, shutting down all the power and turning it back on, one circuit at a time, to see which component comes back to life.

Use a Sharpie or label machine to identify the room or appliance to which each breaker switch corresponds (dedicated circuits will power one item — like the central air conditioner, for instance — while branch circuits supply power to a range of outlets, lights or switches within a room or section of your house).

It makes no sense to leave non-essential circuits on when you head off for an extended vacation or just long weekend, so pickup some of those handy little colored dot stickers to identify circuits that can be switched off when you go away. Doing so not only stops vampire power that “leaks” out of appliances like television sets (even when they are off!) but also reduces the risk of electrical fires.

Use red dots for circuits in which power always needs to be on — security lights and your refrigerator, for instance. Then use green dots to mark circuits that can be turned off for times you’ll be away — things like room lights and electronics.

Truly vintage electrical systems involve another safety labeling step: fuses. It’s critical that when a fuse blows, you have the right kind and size to replace it, so make sure to also note that information inside the fuse box, and have a collection of spare fuses ready for installation.

If you’re not sure what size fuse you need, have an electrician check wires sizes the next time you’re scheduled for a basic repair. Fuses are design to blow when a circuit is forced to pull more power than its wiring can handle. Fuse size therefore depends on the size of the wire it is protecting: 15 amp fuses protect #14 wired circuits, 20 amp fuses protect #12 wired circuits and 30 amp fuses are needed for #10 wired circuits.

Finally, never use a fuse bigger than what the wire requires. It not only defeats its purpose, but can allow the wire to overheat and potentially result in an electrical fire.

Can I Treat This Myself? Yes. Basic DIY skills are all that’s necessary to label your circuit breakers and fuses. Call an electrician for electrical system repairs, though they’re not for the faint of heart. This is definitely the kind of thing where doing it yourself can turn into hurting yourself if you don’t have the necessary experience and training.

Tom Kraeutler delivers home improvement tips and ideas each week as host of The Money Pit Home Improvement Show, a nationally syndicated radio program. He is also author of My Home, My Money Pit: Your Guide to Every Home Improvement Adventure. You can also subscribe to Tom’s latest home improvement podcast or free home improvement newsletter.

** Got a DIY disaster you’d like us to feature? Send a photo of the disaster to, and we just might publish it here on DIY Life. All submissions will remain anonymous. **

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