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Old 08-15-2010, 07:39 AM   #16
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2 TVs fried: Electrical vs. Comcast Coax Cable Problem


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Originally Posted by AllanJ View Post
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.

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Old 07-16-2012, 07:49 PM   #17
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2 TVs fried: Electrical vs. Comcast Coax Cable Problem


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.
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Old 07-16-2012, 08:01 PM   #18
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2 TVs fried: Electrical vs. Comcast Coax Cable Problem


Quote:
Originally Posted by Lee Daughton View Post
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.

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

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