Ask Me Help Desk - TV interference (intermittent)

I am experiencing intermittent TV interference (a brief moment of pixelation and drop or "pop" in audio), which occurs when lights, the air conditioner, a ceiling fan or bathroom fans turn on or off from ANYWHERE in the house (not just in the TV living room area)

How I have attempted to isolate the cause of the interference:

Antenna reception/interference? - Nope. I have a digital antenna in my attic, and first thought this was the culprit. However, I then noticed the analog cable from COX has the same interference, even when I unplug the antenna coax. So it isn't caused by the antenna and/or poor reception. By the way, all my channels come it at full signal strength.
Antenna in the attic instead of on the roof? - Nope. I have tested the antenna outside on the roof and the problem is the same.
Dirty power or Radio frequency interference? - Nope. I have tried ferrite beads/coils, and EMI chokes on my coax cables. I have also tried surge protectors with EMI noise reduction (70dB), and CleanPower technology. The result: no improvement.
Circuit overload? - Nope. Oddly enough I had all my A/V equipment running, and I plugged in our 12amp vacuum cleaner into the same 15amp outlet, and the reception didn't even give a hint of flickering or interference whatsoever!
Need a dedicated circuit (home run)? - Nope. I ran an extension cord to my disposal outlet -- a 20amp dedicated circuit. The result: no improvement.
Need an Uninterrupted Power Supply (UPS) or Automatic Voltage Regulator (AVR)? - Nope. I wondering if the brief interference was possibly caused by a dip or spike in voltage to the house, when a device is powered on or off. I bought a UPS with AVR. The result: no improvement.

What I suspect may be the cause of the problem:

Poor grounding? - While I have grounded the antenna with a grounding block and groundwire, I saw no improvement. However, I suspect that maybe the entire house isn't grounded properly. Poor grounding could explain why the whole house is affected, not just a specific circuit. In addition, my recent studies have talked about the importance to have electronic devices properly grounded to reduce transmitted interference.
A loose neutral? - This is out of my area of expertise, but an electrician mentioned this could be the problem. Does this sound correct?? Can these interference symptoms I have described be caused by a faulty/loose neutral? Is that something I can check for and/or tighten up myself?

Any ideas? PLEASE HELP!

Totally agree. A loose neutral and poor grounding can be one in the same. The ground potential is moving when the load changes. Not a good thing.

Checking is possible. Fixing, not likely.

Removing the coax annd measuring the voltage from ground on the outlet and the coax (threads) on the TV would be where I would start.

Assume no sub-panels involved.

A ground block should be installed for the cable connection and the antenna. That will help, but the primary purpose id to bleed of static charges.

I'd look at how, the phone, TV and electrical service is grounded and while I was at it, I'd look at how the water system is bonded.
By look, I mean see if the connections are tight and see if the come together at one point. No the topology.

The next tests are harder and believe it or not, you can get zapped by a bad ground. In this case, you cannot assume ground is ground.

Yes, you can inspect the ground connections using insulated gloves and tighten, at least for the copper ones.

Now the fun part. You would be using a sensitive scale of a voltmeter (Millivolts) after you checked on a higher range and would measure from say the neutral wire to the lug it's attached to to see if there is some sort of voltage drop at the connection. You'd also be looking for discoloration and if you had an IR thermometer, looking for differences in terminal temperature. Look at the mains as well.

DO NOT TIGHTEN! At this point if you identify anything uou have to stop. The aluminum wiring that's used USED requires an anti-oxidant paste and you can't apply it without removing and cleaning the conductors with power off.

The neutral/ground bond also has to be looked at. Moving it with mains voltages applied can damage connected equipment.
Tightening the neutral/ground bond should be dome with the main breaker off.

You also need to look at the voltage symmetry. Other issues can occur at the overhead feed, for instance.

The utility can do some power quality monitoring for a week or so if noting is found visually.

Quote:

Originally Posted by KeepItSimpleStupid

Totally agree. A loose neutral and poor grounding can be one in the same. The ground potential is moving when the load changes. Not a good thing.

Many thanks for your response. I will get equipment to do some basic testing on my own.

Should I be concerned about our safety? Or is this grounding/neutral issue more of annoyance than a fire hazard, for example?

We don't know what it is, so we can't say for sure. Neutral/Ground bods can wreck havoc with sensitive electronics.

Heat and sparks can damage terminals.

When it's applied to a pool, it could mean an electrocution hazard.

Whatever it is, it needs to be addressed.

Quote:

Originally Posted by KeepItSimpleStupid

Heat and sparks can damage terminals...

Speaking of undesired heat, not sure if this is related or not, but in the hopes that it could be a clue, since we have been in this house (built in 2005) our digital thermometer that controls the AC always goes up a 3-5 degrees whenever a major appliance is used. Specifically the washer/dryer, dishwasher.

Just wondering if this heat is by chance a side effect of my grounding/neutral issue, and perhaps the issue is causing abnormal heating which is also detected within the walls (cause the temp in house feels normal still). We keep our themostat at 83 (we live in the Phoenix area). When we do laundry or run the dishwasher the house temp on the thermostat goes up to 86 or so.

Are these two issue connected?

No. It's just an additional heat load.