Upstairs circuit in house is noisy

Question

first of all, I'm sorry if I'm posting in the wrong community. I looked for a stack community more related to my issue but couldn't find one.

Here's my issue: all the outlets on the 2nd story of my brother's house have the same problem. When a phone is charged through any of the outlets, the touch screen on the phone behaves erratically. Through some research online, I've found out that this is usually caused by noisy 3rd-party chargers, but this issue is present with genuine chargers as well. So I'm assuming it's the circuit behind the charger that is noisy. I tested the outlets with a wattmeter - both frequency and voltage are within normal ranges.

Any idea why a house circuit would be this noisy? And if there is a safe way to fix it without hiring an electrician? My brother hired an electrician recently to take a look but he couldn't figure it out. He's letting me live at his house rent-free for a bit so I'd really like to figure out what's going on to help him out.

Any suggestions are welcome!

Answer 1

One possible cause for electrical noises are loose connections on the back of the outlet. For example, where the internal mains wiring physically connects to the scews or push in terminals on the outlet, if these are not tight, or are worn out and loose, a noise can be generated.

Recommend checking and replacing if necessary. Also, when replacing a outlet you might need to replace with a AFCI and or GFCI/DFCI type outlet per code requirements. Some jurisdictions may not require this but you can still do it for safety.

Answer 2

It can be very, very difficult and time consuming to track down the sources of electrical noise. You're at an advantage if the noise is always present, it's much easier to troubleshoot than if the problem is intermittent.

The first thing to do is figure out what circuit or circuits the upstairs receptacles are on. This may be easy if the panel is clearly labelled but I'd verify the label is accurate by shutting off the breakers and confirming the outlets are dead.

If the labelling on the panel is not clear, which it usually is not, you'll just have to have one person at the panel turning off breakers, and another person going from receptacle to receptacle. It might be a good idea to use a simple receptacle tester for this, it might find miswired receptacles, which might or might not be related to this problem.

Then the first test I'd make would be to shut off all the breakers in the house except the noisy circuit and see if there's still noise. This tells you whether the problem is from another circuit. If the noise vanishes, turn on the breakers one by one and see if one of them brings back the noise.

If the noise is there even when all the other circuits are off, the the problem is probably on the affected circuit. The next step would be to disconnect every load on that circuit - turn off every switch. For example if the problem is coming from compact fluorescent lights on the same circuits, the issue should disappear when those lights are off. New LED lights and dimmers and smart switches can make it a bit complicated to disconnect everything completely, sometimes you even have to disconnect them from the wiring.

As you turn things off and disconnect loads, see if the noise goes away. Unfortunately the only way you can be sure you've turned off everything is to have an amp clamp at the panel and see that current goes to zero.

One more thing to try, and this is a longshot - run a long extension cord down from the upstairs to the downstairs. This would test whether the problem is something in proximity to the upstairs rooms, something in the attic, something like that.