# 2 TVs fried: Electrical vs. Comcast Coax Cable Problem



## gregzoll (Dec 25, 2006)

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 (Mar 13, 2005)

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


----------



## AllanJ (Nov 24, 2007)

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.


----------



## 86548 (Aug 12, 2010)

*How did you conclude this, just for my own understanding*



gregzoll said:


> 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.


----------



## 86548 (Aug 12, 2010)

*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


----------



## 86548 (Aug 12, 2010)

AllanJ said:


> 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 (Jan 16, 2009)

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 (Sep 11, 2008)

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 (Jul 11, 2008)

LynOprinka said:


> 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 (Nov 24, 2007)

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 (Nov 24, 2007)

kbsparky said:


> 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 (Mar 3, 2007)

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


----------



## 86548 (Aug 12, 2010)

*Comcast tech*



Yoyizit said:


> 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.


----------



## 86548 (Aug 12, 2010)

*UPS vs. surge protector*



bobelectric said:


> 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.


----------



## kbsparky (Sep 11, 2008)

AllanJ said:


> RE: the beach house case
> 
> Did the power company pay for all the damage including the melted cable company's pedestal?


I don' know. They let their insurance company battle that out with the utility.

Probably got some reimbursement once the facts were all known. :huh:


----------



## Lee Daughton (Jul 16, 2012)

I have been reading the posts here since I have a similar problem. Some posts insinuate that you have a "Floating" neutral at the pole, however if you did you would , then you would have some lights in your house that would appear brighter than normal and some that would appear dimmer than normal and switching lights on randomly would cause the lights to change in illuminance , which I would think that you'd notice. 240v appliances would be totally uneffected since loss of an incoming phase conductor would cause a total loss of power to any 240v device. As one poster noted that the cable pedistal caught fire , yea the neutral floated and since the cable system was properly "Bonded" (technically more code recognized description) ,the cable shield tried to carry the neutral current to the pedistal and then to electrical system ground peg at the pole. This condition could happen in a structure with minimal supervision and small electrical loads such as a refrigerator. The cable shield is of seriously insufficient size to carry any substantial amount of current and would deffinently overheat and possible catch fire. As another poster noted the "NEC" in articles 820 and 830 address bonding and grounding of cable systems amongst other issues pertaining to cable installation. Cable system grounding and bonding is an issue which generrally gets neglected and causes many pieces of burnt equipment. In general it takes 2 wires to create an electrical or signal circuit , 1 wire being the center signal conductor ,and 1 wire (Shield) as the other conductor. Since the center conductor voltage uses the shield as its reference 0v to develop a potential difference (Voltage) it is absolutely necessary that the shield be bonded and grounded throughout the system to prevent widely fluctuating voltages that may occur much like a floating neutral. In my situation we suffered a lightning strike near my residence killing my expensive wide screen. Since it was under warranty , Samsung ,(cant say enough good things about my TV and their service) , sent out a service tech to repair. I had initialy considered a power surge as the culprit , however the tech said the motherboard was burnt and not the power supply. I really wasn't surprised because I have all my computers and TV behind a 240/120 isolation transformer , 240v input ,120v output , negating the afformentioned floating neutral problem. After the tech got my TV working I found that only the HDMI output of my converter box ,not the S video and RCA audio outputs which I was using temporarily on my old TV , had failed ,this led me to beleive that issue was created by a surge on the incoming cable wire. Drove to my local cable company store and swapped the box and all was fine again. Had a lighting storm again last night and my wide screen died exibiting the same blink codes as the previous time. Wont know about the converter box till the tech repairs my wide screen since it's the only device I have that works on an HDMI feed. An interesting note: We have 2 TV cards in our computers through DTA's and my wife's computer TV was on and unaffected where as the cable converting box and my wide screen were turned off since I saw the storm coming and didn't want a repeat of the same issue as the first time. The DTA's are connected to TV cards in our computers and solidly grounded by a 3wire cord to the electrical system ground conductor where as the converter box and TV are connected by 2wire ungrounded factory cables. The cable company should have grounds on their system and a ground , technically a bond, wire should also be connected to your electrical system grounding conductor at your main service to a terminal connector at the cable entrance location. Floating cable grounds may also cause slow internet connections since the foam dielectric , the white insulating material around the center signal wire , can build up a capacitive charge and inhibit internet speeds. In other words a loose cable shield ground can run the gammit from annoying to disastrous. Fortunately for me , I live in an area with a Electrical Inspection Agency with a thorough knowledge of electrical codes and a special meter which can check grounding integrity. I'll be calling them next to request a check of my cable grounding integrity. You can bet your last dollar I'll get to the bottom of my problem and chew some "Butts" clean off before I'm done. You'll probably have your local cable provider try to pull the old NEC 90.2(B)(4) code which they will contend applies to any area exterior to your home and thusly makes their exterior wiring code exempt. Thats a tricky exemption and doesn't normally fly in our jurisdiction. Typically it applies to their office spaces and server farms. If you don't have a solid local electric inspection authority, a reputable electrical testing agency can make the ground continuity test for a fee.


----------



## stickboy1375 (Apr 28, 2012)

Lee Daughton said:


> I have been reading the posts here since I have a similar problem. Some posts insinuate that you have a "Floating" neutral at the pole, however if you did you would , then you would have some lights in your house that would appear brighter than normal and some that would appear dimmer than normal and switching lights on randomly would cause the lights to change in illuminance , which I would think that you'd notice.
> 
> 240v appliances would be totally uneffected since loss of an incoming phase conductor would cause a total loss of power to any 240v device. As one poster noted that the cable pedistal caught fire , yea the neutral floated and since the cable system was properly "Bonded" (technically more code recognized description) ,the cable shield tried to carry the neutral current to the pedistal and then to electrical system ground peg at the pole. This condition could happen in a structure with minimal supervision and small electrical loads such as a refrigerator.
> 
> ...



Edited because apparently the posters 'return' button is broken.


----------

