Diagnosing noisy power lines

Question

We have a number of devices in our house that communicate via power lines (such as power line networking devices and some solar/electric metering equipment), and we've had persistent problems getting a good signal. I've tried the steps outlined in this question, but I haven't had much success in locating the problem.

Are any tools available that would help quantify the nature of the problem...that aren't going to set me back hundreds of dollars? I would love to have some hard data to work with, rather than the rather vague "it's just not working" that I've got right now.

Answer 1

A high school electronics teacher once showed me a trick for finding outlets with loose connections. This might help you too.

Take a portable radio and tune it to a good AM station with a strong signal. Slightly detune the radio so that you can still hear the station, but with a bit of noise. Now walk around with the radio, passing it by outlets, switches, etc. If you get a lot of noise on the radio, you might have found a bad connection. Turn off the power and open up the device. Check all of the terminals, wirenuts, etc. to ensure they are snug.

Answer 2

The thing on getting a good signal with a power line carrier is getting and keeping a perfectly good 360 degree sine wave. With today's modern toys, appliances, TV's baby monitors, cordless chargers for razors and what ever else you can think of dumping noise back onto your power lines, good signals are hard to get. On the link you checked out, Niall C. could not have answered it better. Without spending a fortune on test equipment, do some research and find a good quality surge suppressor strip that will give you good power quality. One of the best is a good UPS.

But the problem is all the noise in your house, and keeping whatever you do to correct the noise and keeping it from treating your PLC signal as noise. It's been years since I've had to do this kind of trouble shooting but it all goes back to what Niall C. pointed out. Unplug electronics, turn off breakers, try surge strips and or a small UPS system. Remember just because you have noise at one time today does not mean you will have noise the time everyday, so try at different times of day.

The cheap way is trial and error. I'm sure you are not the only one with this problem today so keep googling and checking chat rooms dealing with this kind of technology. If you want a quick fix, you'll have to pay for a professional and with noise on power lines, even it might take them a few trips.

Answer 3

For power line communication devices to operate correctly they should be on the same leg of the power lines coming into the house. Your house has two power legs and a neutral leg. Voltage from each leg to neutral is nominally 120 volts AC. Voltage from leg 1 to leg 2 is nominally 220 volts. The power line modules work best when all devices are connected to the same leg. If one device is connected to leg 1 and the other device is connected to leg 2, the signal could have to return to the utility transformer (on the pole and could be blocks away) before reaching the other leg.

The quick fix, if you can, is to swap breakers in your main panel so that all power line modules are on the same leg. If you can not do that,this bridge may help. Although this is designed for the "X10" system, they all work pretty much the same and could work as well for your system.

The breakers alternate from leg 1 to leg 2 as shown.