Voltage on Cable Line

Bud-- wrote:
<snip>


http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf
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ehsjr wrote:

http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf

That works a lot better. Thanks
-- bud--
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Gave us:

I do not dispute your references at all. All I stated was that was what our employer required us to do. His inspectors even sent us back to sights which failed their inspections.

We had several at the pitch of three story or greater apartment buildings that were as long as the building is tall.

We were post wiring 12 to 50 unit structures.

This is all well and good, but does not change the fact of what they had us doing. I am sure they have modified their practices since 1979 though.

Cool.

I do not disagree.

I totally agree. Asshole installers from all involved walks of life cut corners when the real work requisite faces them.

No shirt Shitlock.

I watched my cable internet speed drop overnight after a cable installer "worked" inside our lockbox.
The original installer said my signal was GREAT. and my cable speed reflected that 7Mb/s in and 0.5 out. After the "phone guy" changed out the port taps in our lock box, I got 5Mb/s in, and was getting failures on outgoing packets. I am sure the signal strength has dropped, and would bet so. Now, it likely has spurs.
To this day it has never been the same, but Cox did "upgrade us all", and now I get 10Mb/s in and my old 0.5 out, but it still hiccups a lot on the out side, which is an ATM link, differing from the incoming transport mechanism.
So I have seen where the cable co can screw up even one's "digital reception" for one's internet link by no more than a few poorly cut fittings.
His problems, however, do point toward a house wiring issue, and other did have the same feeling. Sure it is quite possible that it is the cable co, but if they come out and read his attenuation level at his end of line, and it is OK, then it is NOT the cable co. It COULD be the cable modem.
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JoeBloe wrote:

Joe Your position reveals a failure to train and supervise on the part of Warner Amex CUBE system. The National Electric Code and all of the local codes that are based on it requires that separate grounding electrodes be bonded together into a single grounding electrode system. Cable installers working on buildings rather than poles or hand holes are not exempt from that requirement. Every one of those separate rods is a destructive surge path waiting to happen.
--
Tom Horne

Well we aren't no thin blue heroes and yet we aren't no blackguards to.
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On Sat, 06 Jan 2007 22:15:29 GMT Thomas D. Horne, FF EMT
| JoeBloe wrote:
|> Gave us: |> |>> Verify that the ground block at the cable entry is connected to the |>> grounding system for the power. It can't (in the US) just be connected |>> to its own ground rod. |> |> |> Not true. We were REQUIRED to drive OUR OWN 8 ft rod whenever we |> did a post wire on an apartment complex. |> |> This was Time Warner (Warner Amex CUBE system at the time) |> |> Single home drops MAY be attached at the house tie point, or a ground |> rod CAN be driven. It is for lightning protection, and the problems |> being discussed in this thread are not related to that. |> |> That alone points toward the issue being with HIS power wiring, and |> NOT the cable system. | | Joe | Your position reveals a failure to train and supervise on the part of | Warner Amex CUBE system. The National Electric Code and all of the | local codes that are based on it requires that separate grounding | electrodes be bonded together into a single grounding electrode system. | Cable installers working on buildings rather than poles or hand holes | are not exempt from that requirement. Every one of those separate rods | is a destructive surge path waiting to happen.
I Agree 100% with Tom's position. I also have to admit that despite so many other failures and lack of training among Comcast technicians or their managers, and the company in general, this (connecting all the ground rods solidly together) happens to be one thing they got right. The previous cable system operator here didn't do it right, and that's one of the things Comcast is working on now, for almost the entire system, re-wiring every home to get the grounding correct. They are just not putting enough manpower into it. But at least they know how it's supposed to be wired.
--
|---------------------------------------/----------------------------------|
| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |
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On Sat, 06 Jan 2007 22:15:29 GMT, "Thomas D. Horne, FF EMT"

No. That IS what was being trained at the time, and they even went out with installation auditors and ultrasounded the rods to make sure no installers were cutting them off. That was 1979.

No shit.

Never said they were.

Perhaps.
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snipped-for-privacy@gmail.com wrote:

It sounds like you might have a bad neutral (grounded conductor) between the power company transformer and the power entrance into the house. Either a bad connection or the wire itself is bad. That wire carries current just like the "hot" wires do. The current can't flow on the neutral so it's trying to follow your coax instead. It's trying to flow back to the utility's transformer. It's a dangerous condition if my guess is right. Time for an electrician unless you're familiar with such things. You might ask the electrician about a 4 wire service from the utility's transformer to your house. It's a safer set up.
Dean
-
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Dean:
Yours is the post that makes the most sense to me. I'm not an electrician, but if I understand correctly, the ground exists in case there is a problem with the neutral - that way the current has a way out other than through me or something else I don't want current flowing through. So if the neutral is bad, the current is looking for a way out, and some of it is finding the incoming coax when it's connected and going out that way.
So assuming that the neutral could be bad, it could either be a bad connection or wire inside my house, or could it be the feed from the power company to my house? For obvious reasons, I'd prefer the power company to come out and fix something outside my house rather than me paying an electrician to fix something inside.
If it probably is inside my house, what would I look for in tracking it down? It's in all the outlets, so it has to be at the main service panel somehow, right? Making it either the power company's feed or something bad inside the fuse box, if I'm guessing right.
Thanks alot for your help.
Matt
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snipped-for-privacy@gmail.com wrote:

Not quite. The ground rods at a house are there mainly for lightning protection. If the neutral (grounded conductor) between the house and utility is bad, a bit of current can flow through the ground rod, through the soil and back to the utility company's transformer. Some could be flowing through your coax now. The rest could flow through a person given the right circumstances. Current will flow through all available conductors, not just the one with the least resistance. That's why this could be dangerous.

More likely from the house to the utility. The neutral (grounded conductor) and equipment ground are connected together in your panel. All three wires going from the house to the utility actually carry current. A problem downstream of your panel would probably cause a light or something to not work. It shouldn't cause stray voltage because the neutral and equipment ground are separate downstream of the panel.

The problem might be the neutral connection as it enters the panel. I would suggest not messing around in the main panel. It would be too easy to make a mistake. There is also an arc or flash hazard in addition to the electrocution hazard. I think burns cause more injuries to electricians than the shocks do. My memory fails me right now at what voltage the flash hazard starts. Electricians are cheap compared to doctors. Good luck.
Dean
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Measuring voltage cannot tell you where the electricity is coming from. You know this. There is a 5 to 13 volt difference between cable and AC electric. Why? This must not happen because cable and AC electric must share a common earthing electrode. AC electric at the mains breaker box and cable must be at 0 volts. Again, this because cable shield and breaker box ground wire both meet at a common earthing electrode.
The purpose of that electrode serves many functions as defined by so many. It is for safety from a failed neutral. For safety so that a human is not electrically shocked. For surge protection.
Therefore inspect the cable where it enters the building. A grounding block (or splitter) is wired to the earthing rod. A thicker bare copper wire leaves breaker box to connect to that same earthing rod.
Although not related to your problem, that earthing rod is solid (cannot be shaken) and is 8 feet into earth. Put up on it and the rod should not rise.
Cable cannot be earth via a water pipe (or faucet) connection. It must be earthing where AC electric and telephone are also earthed; a rod that you (or your agent the electrician or builder) should have installed.
Now, implied is that voltage is in modem. Therefore you can measure voltage between modem and cable center conductor? You can measure same voltage from modem to cable shield connector? You can measure same voltage from modem to ground screw on wall receptacle? You can measure the same voltage from modem to cold water pipe? Based upon how I read your posts, all reading should be that same voltage.
A bad neutral must not create the problem you are seeing because (again) all three utilities (as demanded by code) must connect to the same earthing electrode.
OK, let's say all utilities do connect to the same electrode. This experiment is best done with an extension cord or some other long wire. Measure voltage from modem direct to the earthing electrode. Does a voltage exist? Do same from cable center conductor (the end that would connect to modem) to earthing electrode. Any voltage? Cable shield to electrode. Voltage? Grounding screw on wall receptacle to earthing electrode. Voltage? In each case, no voltage (less than 1 volt) should appear. For more thorough responses, list what each voltage measures.
Back to that neutral wire problem. If problem exists, then incandescent bulbs change intensity as major appliances power on and off.
snipped-for-privacy@gmail.com wrote:

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Matt, one thing to consider is that your voltmeter may be reading RF rather than AC particularly if it is a $3 drugstore special.
if this is the case there may be nothing intrinsically wrong with you house wiring or grounding.
you might try repeating the measurements with a .01 uF (or thereabouts) capacitor across the meter and see if it makes a difference.
if so a different approach may be called for.
i cannot speak for all cable installers, however the ones who wired one of my facilities were completely and totally incompetent. it took many months and many calls to get most of the issues resolved and the modems to be generally reliable. after switching to TI and turning off cable life was much better.
my recommendation is to politely but firmly and repeatedly insist on an inspection by the "head end technician". this is what the cable industry calls the chief engineer. with luck this will be an experienced and knowledgeable individual armed with advanced test equipment. if he says everything is OK from our end there is nothing more we can do then you can procede with troubleshooting the house grounding/electrical system.
in the end you may have to use a 'cable ground loop isolator' but see what the head end tech recomends first.
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On 1/2/07 1:19 PM, in article snipped-for-privacy@a3g2000cwd.googlegroups.com, " snipped-for-privacy@gmail.com"

Without fully understanding your problem, I have some suggestions.
1. Run your modem power through an isolation transformer.
2. Run your signal through a line transformer.
That is, avoid your problems with multiple grounds rather than track them down.
Bill -- Fermez le Bush
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Gave us:

Show me a single cable installation that has a "line transformer" on it.
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On 1/3/07 5:12 AM, in article snipped-for-privacy@4ax.com,

I cannot because I am not up on the subject. There certainly are broadband (pulse) transformers available with much greater bandwidth than is required for typical DSL. Transformer exist that use transmission line transformers for high frequencies that simultaneously use iron cores to support low frequencies.
Bill -- Fermez le Bush
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snipped-for-privacy@gmail.com wrote:

Chances are it's not your wiring and there's something wrong with at the cable company or with their equipment. Here's a summary of the problems I've encountered in the last few years:
I had a cousin who had a DSL problem. Her ISP said it was her computer. I told her it wasn't and she probably had a bad modem. The problem went on for weeks while they were giving her the run around. Finally she called them and told them she was canceling her account. They came to her house and replaced the modem and everything was fine.
I have an ex-son-in-law who's been going round and round with his cable company for weeks because his television only worked good sometimes--mostly at night. Actually, he had the same problem several months before that and a serviceman had fixed it. Anyway they had him trying everything and changing cables and promising someone would come out, etc. When the serviceman finally arrived, he told him the problem was because he was using RG-59 instead of RG-62, but actually it turned out the signal coming into his apartment was too weak.
I used to have DSL and came home one day from my daughter's house after a huge thunderstorm--one of the worst ones I've ever seen. Fortunately, everything still worked because now days most equipment has built-in surge protection. Everything still worked, that is, except my DSL connection. Upon taking a close look at the modem, I noticed it lacked a "CE" mark and, therefore, probably didn't have good surge protection. My ISP had me jumping through hoops for 3 weeks talking to their service center in India. Finally, a guy came out and replaced the modem. By then, though, I was so damned mad I canceled the service and went with a fiber optic connection. I had to buy my own modem, but they gave me a recommended model number (a Wireless - B Linksys).
Everything worked fine for a couple of weeks until I decided to download some music from Napster. Then I would always get disconnected for some mysterious reason. I called my ISP and they told me to call Napster. I did and Napster told me to contact my ISP (again). After that my ISP ran some tests and said everything was fine, but of course it wasn't. Finally, on about my 4th call a guy asked me what kind of Modem I had and then told me I needed to switch to a Wireless - G Linksys. That solved the problem.
Anyway, good luck. I hope you get it fixed soon.
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