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-   -   2 TVs fried: Electrical vs. Comcast Coax Cable Problem (http://www.diychatroom.com/f18/2-tvs-fried-electrical-vs-comcast-coax-cable-problem-78598/)

LynOprinka 08-12-2010 06:53 PM

2 TVs fried: Electrical vs. Comcast Coax Cable Problem
 
Hi everyone, I am trying to tell if I have an electrical grounding problem or a Comcast Cable problem (or both).

I have recently had problems with my Comcast tv reception, I was not getting channels 50-60. I would just get no signal at all or blocks of color but not a whole picture. Comcast came out once, quickly diagnosed it as a fried cable box, replaced the box and left. All the channels worked that evening. By the next day though, the problem was back.

Comcast came back out. This time I followed the tech everywhere she went (female tech this time, first time ever...) and asked a ton of questions. I told her I had had trouble with my service for years, (dropping internet connection was my most frequent complaint). Over the years I have replaced the modem, and replaced router. Sometimes I would call comcast and the Tech would come out, do something quick and it would be better for a while. As I was telling her all this I also realized we had a computer that died, as well as 2 TV's that died in the past year. All had fried motherboards.

Then the tech got shocked touching the coax cable splitter. I told her the last comcast tech had said the same thing (and did nothing else about it). This tech called in the escalation team. They came, discovered the coax line into the house was brittle. Replaced it through out the house. Climbed up to the pole and said their was water damage in the coax. Replaced the coax from the pole to the house. Took the coax ground off the electrical meter and put it into the earth ground the phone company had there.

I had a handyman come out. He checked my outlets Said my house has multiple ungrounded outlets. Its a 1957 ranch. Someone replaced the 2 prong outlets with 3 prong outlets without connecting a ground.

Electrical company came out and said it wasnt their fault, and I could replace all the outlets with GFCI's, and be up to code, (but that wont protect my electronics, just my family.) They did notice oxidation on the water pipe next to the ground and tightened that. (Had to replace the H2O tank in the last few years.... also related?)

Cable company says its the ground problem thats using the coax to find a ground and they are not liable. But I've never gotten shocked, lights never flicker, nothing has ever gotten damaged except things connected to the coax cable. And the coax line had water damage. And why did they move the ground? Are they covering something up that I dont know enough about to question them?

I have a damage claim filed with Comcast for the tvs. Is this reasonable? Have an electrician on the way too...

Thanks for any help, LYN

gregzoll 08-12-2010 07:21 PM

Not a Comcast problem. Get an electrician, because you have a loose Neutral at the drop from the pole, which is causing the system not to have a return path for ground. Also, have the electrician check your grounds to the ground rod, etc. This means opening up the wallet, and paying out some good money.

joed 08-12-2010 08:09 PM

The Comcast and phone ground should by code be connected to the electrical system ground.

AllanJ 08-13-2010 05:38 AM

If your electrical grounding system is old or of unknown quality, you should run a makeshift ground for your electronic equipment. Run a single 14 gauge wire daisy chaining or branching from one piece of equipment (including splitters) to another, screwed on to each piece by a screw that goes through to the chassis or attached to the equipment at the shell of one of the input jacks in the rear. The far end of the wire is connected to a known ground such as a metal water pipe (within 5 feet of its) exiting the basement and underground, or to a ground rod. Run the ground wire, exposed, along baseboards and up and around doorways as needed to get to the known ground. (Your electrical system should have a #6 or fatter wire running between the panel ground lugs (ground bus) and the ground rod and/or water pipe and you can attach your makeshift ground to the middle of that if convenient.

Now use a voltmeter to measure voltage (both AC and DC) between the coax cable plug (both the outside shell and the inner pin) and the other voltmeter probe for all four tests goes to your makeshift ground. If you get a reading of more than five volts then there is some kind of electrical problem, likely in the cable company's equipment.

Do not connect the coax cable to your TV or computer if the inner pin to ground reading is more than five volts.

LynOprinka 08-13-2010 01:09 PM

How did you conclude this, just for my own understanding
 
Quote:

Originally Posted by gregzoll (Post 484882)
Not a Comcast problem. Get an electrician, because you have a loose Neutral at the drop from the pole, which is causing the system not to have a return path for ground. Also, have the electrician check your grounds to the ground rod, etc. This means opening up the wallet, and paying out some good money.


Gregzoll, thanks for the response, I don't mind paying good money for someone to properly fix the true problem, but what I have found being a homeowner, is that A) people come and do something in your house, B) It may or may not have been what was actually needed (i.e. incorrect diagnosis) , C) They may or may not have completed it correctly (i.e. shoddy workmanship/inexperience/incompetence).

Whether or not I do the work, I have come to realize it is essential to understand the problem, because I am essentially supervising the work. Otherwise work gets done, and I'm either still left with the problem, or its a bad fix, and then I have to start over again.

So can you explain how you deduce its a "Loose neutral at the drop at the pole." Is it the oxidation that indicates that?

I can follow checking all the grounds, as I can see that the ground "chain" is not working somewhere in the house, but how would one know it goes all the way back to the pole?

Thanks for your help.

LynOprinka 08-13-2010 01:22 PM

forgot... Why no Comcast issue?
 
Also everyone who answered could you explain why do you conclude Comcast has no roll?

My pet theory was that some interaction was happening between the Electrical service drop and the Comcast drop at the pole (which has a large transformer), or on the way to the house, or at the entry to the house (where the positive and negative are right beside each other and the cable line) , and that the water damage in the comcast line at the pole was allowing some electrical charge/voltage to come into the house via the coax cable and blow up electronic appliances that use the coax cable. This would be entirely separate from the house ground issue. Is that not possible?

I guess what I am asking is how would one know the damage comes from a poor ground and a return current issue or a delivery of too much current to begin with?

Doesn't their line being water damaged, for an extended period of time (2 techs came on separate visits and got shocked) with their not addressing it, and their tech grounding up the coax improperly mean anything?

Thanks, Lyn

LynOprinka 08-13-2010 01:30 PM

Quote:

Originally Posted by AllanJ (Post 485029)
If your electrical grounding system is old or of unknown quality, you should run a makeshift ground for your electronic equipment. Run a single 14 gauge wire daisy chaining or branching from one piece of equipment (including splitters) to another, screwed on to each piece by a screw that goes through to the chassis or attached to the equipment at the shell of one of the input jacks in the rear. The far end of the wire is connected to a known ground such as a metal water pipe (within 5 feet of its) exiting the basement and underground, or to a ground rod. Run the ground wire, exposed, along baseboards and up and around doorways as needed to get to the known ground. (Your electrical system should have a #6 or fatter wire running between the panel ground lugs (ground bus) and the ground rod and/or water pipe and you can attach your makeshift ground to the middle of that if convenient.

Now use a voltmeter to measure voltage (both AC and DC) between the coax cable plug (both the outside shell and the inner pin) and the other voltmeter probe for all four tests goes to your makeshift ground. If you get a reading of more than five volts then there is some kind of electrical problem, likely in the cable company's equipment.

Do not connect the coax cable to your TV or computer if the inner pin to ground reading is more than five volts.

All that detail is very helpful, thanks. Is the daisy chain idea better that trying to run grounds from all the individual outlets back to the panel? The house has a finished basement under half of it, so I haven't gone very far with this because I can't picture how anyone is going to fish a ground blindly through 12 ft of ceiling tile (for the outlets on the walls farthest from the unfinshed part of the basement).

My neighbor suggested running a new, grounded outlet on its own circuit straight to the place I plug in the TV and plug all the electronics in there. Seems too constraining in terms of future locations of electronics....

Scuba_Dave 08-13-2010 01:39 PM

My Tv & computer are plugged into UPS
Easily moved to where needed
I would install a grounded circuit if you can
Especially if you have easy access thru basement or attic

kbsparky 08-13-2010 09:11 PM

We encountered a job where the underground neutral conductor from the utility went bad. This was on a beach property, which was not occupied all the time.

Folks came down from the big city to their beach place on a Friday night, and discovered that many of their lights and appliances were not operating properly.

I went down there to investigate, and discovered their main neutral conductor was bad .... also we found that the entire length of coax cable from ComCast was melted!! Over 150 feet if I remember correctly.

Further investigation revealed that 2 weeks before that, the CATV pedestal out by the highway had caught fire! It was quite a spectacle with that little pedestal shooting out flames high into the night sky!!

ComCast then disconnected the offending piece of coax coming from this vacant beach house and replaced their pedestal.

The outer shield of that coax was not sufficient of a conductor to handle the entire neutral current of the beach house, even though it was vacant. Probably the fridge and freezer was enough to melt that wire, and set the pedestal ablaze. They are lucky their house didn't burn down as well.

The ultimate cure for the problem was to get the power company involved: Locate the bad piece of wire, Dig up the yard, and repair that neutral.

The damages?

All the ComCast boxes, most of the TV sets, several ballasts, bulbs, chime transformer, and one fridge were all fried. Total went into the thousands of $$$, including paying off ComCast for their equipment and repair costs.

I really don't blame your CC rep for disconnecting the intersystem bonding conductor, even though that is a Code violation. They are only trying to protect their equipment from meltdown. They should have made their case a bit stronger that you have a bad neutral which is making excess voltage appear on the main grounding electrode conductor, and the intersystem bonding grid along with it.

So, get an electrician involved, as well as the power company, and FIX the problem!!! :furious:

Yoyizit 08-13-2010 09:28 PM

Quote:

Originally Posted by LynOprinka (Post 484861)
Then the tech got shocked touching the coax cable splitter.
1
discovered the coax line into the house was brittle. Replaced it through out the house. Climbed up to the pole and said their was water damage in the coax. Replaced the coax from the pole to the house. Took the coax ground off the electrical meter and put it into the earth ground the phone company had there.
2

1 and what else was she touching?
2 did all that fix the original problem of the splitter being energized?

AllanJ 08-14-2010 06:20 AM

When you make your measurements, do not use/treat the cable company's coax as a known ground.

Since the cable company technician got shocked, we cannot rule out a problem in the cable company's equipment including up on the utility pole or in a pedestal.

RE: the beach house case

Did the power company pay for all the damage including the melted cable company's pedestal?

AllanJ 08-14-2010 06:27 AM

Quote:

Originally Posted by kbsparky (Post 485435)
I really don't blame your CC rep for disconnecting the intersystem bonding conductor, even though that is a Code violation.:

That can make matters worse, and even lead to the pedestal meltdown described in anoter reply above.

We don't need to have the cable company make some surreptitious change in the homeowner's sysetem and then blame the homeowner when things including the cable equipment gets fried.

The makeshift ground wire I described, strung even if the receptacle is already properly grounded, will help to prevent all of the other problems.

Correction, I would not connect cable boxes and equipment belonging to them to the makeshift ground. Don't want to make it look like I tampered or drilled holes into their equipment.

bobelectric 08-14-2010 06:45 AM

You need a service upgrade with dedicated outlets. Listen to your neighbor!

LynOprinka 08-14-2010 03:37 PM

Comcast tech
 
Quote:

Originally Posted by Yoyizit (Post 485441)
1 and what else was she touching?
2 did all that fix the original problem of the splitter being energized?

Yoyizit, Once Comcast replaced all their line (and moved the ground), the charge in the splitter is gone.

Neither tech was touching anything else when they got shocked (that I'm aware of.)

Interestingly, before they replaced all the line the charge dispersed for a short time when the tech unscrewed the splitter from the lines and reconnected it, and then the charge was back after a few minutes.

LynOprinka 08-14-2010 03:43 PM

UPS vs. surge protector
 
Quote:

Originally Posted by bobelectric (Post 485539)
You need a service upgrade with dedicated outlets. Listen to your neighbor!

Yeah, I'm thinking that is going to be the fix for the outlet problem, after everything is checked out and any ground issues are addressed.

What are peoples experience with UPS, a power supply that holds power during outages and also functions as a surge and spike protector?

Is it overkill to have a new circuit run and use a UPS. They seem to be about the same price as a surge protector, but they do more.


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