Electrical Troubleshooting Quiz — November 4, 2025

You work for an electrical services firm that got a call from the owner of a six-unit multi-family residential building. He tried to change a kitchen receptacle and got shocked. He knows he had the right breaker, because when he opened the one shown as “kitchen receptacles” on the circuit directory the power light on the tenant’s coffee maker went out. It’s at the other end of the main counter, so clearly it’s a kitchen receptacle.

His reason for replacing the receptacle is that it is starting to corrode from the power backfeed. He says he needs an electrician to come out and fix the backfed receptacle problem. This receptacle is located in the small countertop island next to the range, and he doesn’t want his tenant to get electrocuted just for boiling some water.

How would you go about diagnosing this issue, and what should you tell this customer about these receptacle problems?

Answer to Quiz

Start by visually examining the receptacle faceplate and exposed outlet faces for signs of corrosion. Chances are there’s a bit of green (copper oxide) on one of the outlets. The tenant may be putting more steam into the air than the hood fan or other device can dissipate. The receptacle can be cleaned off with a nylon brush and the tenant instructed to properly ventilate the kitchen. To clean safely, the circuit will be deenergized.

Next, explain to the customer that residential circuit layout isn’t always based on what’s easiest for the troubleshooting electrician. A receptacle on an island might not go with kitchen receptacles but might instead pick up its power from a lighting circuit that’s run up from the floor almost in a straight line with the receptacle. So, you really can’t rely 100% on the circuit directory. You always have to verify the absence of power on the specific circuit you intend to work on.

After this, tell the customer you are going to identify the circuit breaker for that receptacle, using an instrument made just for that purpose. Plug the transmitter into the receptacle and observe the lights. If there’s a problem, make a note of it. Typically, there’s no problem on such circuits unless an unqualified person makes alterations. Locate the breaker and open it.

Check the transmitter lights, they should all be off. Remove the transmitter. Now show the customer a two-step procedure he can use since he does not have a transmitter. Use a non-contact voltage stick to check for power at that receptacle. Tell him this takes the place of the transmitter for a preliminary voltage check. Based on not detecting something, you will carefully remove the receptacle far enough for the second step. That is to check for power using a DMM. If it shows zero volts, put the DMM on a circuit that has power to verify it is reading correctly. Then go back and check for zero volts.

Pull that receptacle out. If it is actually corroded, then replace it. Make sure to tell the customer he made a good call on this one.

It would cost a lot of money for this customer to pay you to identify the circuit for every receptacle and every switch in every room of each of the six units. Suggest he buy a circuit tracer. He should keep notes as he goes and be very precise.

For example, instead of “kitchen receptacles” he can write “kitchen receptacles s wall, w wall, first 2 on n wall”. There’s not room in a standard circuit directory for such detail. But he can put it all on a standard sheet of printer paper (8.5 x 11), using a spreadsheet program to duplicate the layout of the directory but make it bigger. He can then place the finished, verified copy (with the last date of verification) into one of those shipping documents envelopes and stick that to the exterior of the panel door. He should not place it inside the door, as it is flammable and a spark from a breaker trip could ignite it.

If, at this point, he asks about a backfed receptacle you “could” explain why this simply is not possible. But that could make him feel stupid, and he would call some other firm next time. Instead, you can say that was ruled out by means of using the circuit tester and again ruled out by opening that breaker and finding there was subsequently no power to the receptacle.

It’s important that he feels well taken care of but just as important that he feels respected. Some tenants can do a lot of damage to a rental, and you want your firm to be the one he calls next time. There’s also the fact that GFCIs don’t last forever. After about ten years, they are typically due for replacement. If he is happy with how you treated him, he’s going to be amenable to an upsell. Tell him GFCIs last typically ten years and ask him how long ago his were installed. You can also apprise him of the fact that the detector part of a smoke detector uses a radioactive material that is good for only ten years after which the detector can’t be relied on to detect. Hook him up with your sales team to book the appointment.