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Electrician Working On Residential Panel

Electrical Troubleshooting Quiz — November 1, 2022

Nov. 1, 2022
Ways to check breakers other than working them hot

You work for a small electrical services firm. You were sent out on a residential job to replace incandescent can lights with LED can lights and to install LED-compatible dimmers. This work is in two bathrooms, the living room, and the kitchen. The kitchen and living room were no problem, but when you opened the breaker indicated (on the panel directory) for the bathroom lights, the lights stayed on. The homeowner doesn’t want you to just flip breakers until you find the right one. He says you should be able to work it hot, using an insulated screwdriver. How do you resolve this?

Simple testing

In theory, you could work it hot; you could wear insulated gloves and use insulated tools. If you disconnect the supply side of the switch first and reconnect it last, you cut your shock risk in half versus doing it the other way around. But there are three big problems with this:

  1. There’s no compelling reason to work hot, only the convenience of the homeowner.
  2. If the breaker has failed and its failure mode is it does not open, then you will be leaving an unsafe condition behind you.
  3. If the breaker is fine but the directory is wrong, you are also leaving an unsafe condition behind you. Not everyone who opens a residential breaker before exposing conductors will test those conductors to ensure they are de-energized.

You may simply need to correct the directory. Draw it on paper and through testing, properly identify the circuit(s) in question. It isn’t necessary to remap the whole thing and further annoy the homeowner. It is necessary only to find which circuit powers the lights and then identify which circuit it’s swapped with in the directory. Also note there’s no way the 15A breaker for these lights was swapped with the oven circuit or the HVAC circuit. Unless something epically idiotic happened, you can confine your investigation to the 15A breakers.

Let’s say the directory tells you that breaker 6 is for those lights. The most likely problem is the labeling is swapped between two adjacent breakers. If breaker 4 says bathroom receptacles, try operating that to test the lights. Or it may be breaker 8. This simple testing can provide a quick resolution. But let’s say it does not.

Since this is a residential application, it is very likely you are working with a load center rather than a panelboard. The difference between the two is with a panelboard, the breakers are bolted in; with a load center, they snap in. If it’s a load center, you can easily remove and re-add a breaker.

Note the position of each breaker. When you’re done, you’ll need to ensure the breakers are in the positions in which you found them. Normally, that will mean all are closed. But there may be a breaker that is intentionally left open.


If you have a panelboard, you’ll have to shut off the main breaker. This means a lot of extra steps, including setting up portable battery-powered lights. You’ll have to shut off all loads, including the HVAC. You’ll have to unplug major appliances (e.g., refrigerator), plus any minor loads that normally run.

You can use the same troubleshooting technique as we are about to look at for a load center, with the exception that you must have the main breaker opened so you can unbolt the breaker for each individual circuit. And you’ll have to reclose the main to do the testing. This is tedious, and if you’re not careful, it can be lethal. In this case, “careful” means you deliberately impose a method that requires verifying there’s no power past the main any time you will put a tool to a breaker.

Load center

From a load removal standpoint, it’s almost as much work as preparing for opening the main breaker (as required for a panelboard). However,in this case, you can leave on the local lights for the panelboard to avoid all that hassle with setting up lights. And simple testing will be easier.

Ensure the lights and other loads are off in the bathroom and bedroom circuits because you’ll be snapping these breakers out and back in.

Now, remove the load center cover and identify breaker 6. Your hands won’t be near live conductors, but wear your gloves anyhow (the circuit conductor might be fed from another circuit, backfeeding the breaker). Snap out breaker 6. Keep in mind that it’s easy to inadvertently pop out an adjacent breaker, and breakers may be under load when that happens, which is bad. This is why you shut things off beforehand.

With breaker 6 removed from the panel power strip, use your voltage tester on the conductor leaving the breaker. It should be dead, but what if it isn’t? If the conductor on the load side of the breaker still has power, this circuit is cross-wired with another one, probably at a switch or receptacle. It’s unlikely this would happen during construction, so ask the homeowner about anything that was added or changed. You may be able to spot the “amateur work” from visual clues such as a crooked wall plate or a receptacle that is loose. If not, then you’ll have to methodically check behind every wall plate until you find the problem.

If the conductor does not have power, then try to operate the lights.

  • If they came on before but do not come on now, this is the correct breaker. It just does not open, so it needs to be replaced. The 15A breaker typically used in this application is less than $10; make sure the replacement is the same brand as the one you’re replacing and is for a load center.
  • If they came on before and still come on, this is the wrong breaker. Use your directory drawing, not the actual directory, to remap the breaker layout. Only when you have verified you have a correct drawing do you transfer the update to the directory. Else, you might make a mess of the directory.


Once you’ve resolved the breaker swap or bad breaker problem, update the directory if needed. Then you can put the cover back on the load center or panel. Once the cover is secured, check each breaker to ensure it is in the correct position. Failure to do this could mean you leave the occupants without heat or their food spoils in the refrigerator.

Once you’ve completed the originally slated work for those bathrooms, make a final check of the load center to ensure you’ve set all the breakers to their original positions. It might be a good idea to reset the clocks for the homeowner, also. Make sure the refrigerator is plugged in and working. Leave small appliances unplugged, if they were unplugged, so the homeowner knows to do things like reprogram that fancy coffeepot so there’s hot java waiting in the morning.

About the Author

Mark Lamendola

Mark is an expert in maintenance management, having racked up an impressive track record during his time working in the field. He also has extensive knowledge of, and practical expertise with, the National Electrical Code (NEC). Through his consulting business, he provides articles and training materials on electrical topics, specializing in making difficult subjects easy to understand and focusing on the practical aspects of electrical work.

Prior to starting his own business, Mark served as the Technical Editor on EC&M for six years, worked three years in nuclear maintenance, six years as a contract project engineer/project manager, three years as a systems engineer, and three years in plant maintenance management.

Mark earned an AAS degree from Rock Valley College, a BSEET from Columbia Pacific University, and an MBA from Lake Erie College. He’s also completed several related certifications over the years and even was formerly licensed as a Master Electrician. He is a Senior Member of the IEEE and past Chairman of the Kansas City Chapters of both the IEEE and the IEEE Computer Society. Mark also served as the program director for, a board member of, and webmaster of, the Midwest Chapter of the 7x24 Exchange. He has also held memberships with the following organizations: NETA, NFPA, International Association of Webmasters, and Institute of Certified Professional Managers.

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