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Posted By: lite bulb 50 VOLTS ON GROUND - 02/17/06 03:02 AM
I RECENTLY LOST MY COMPUTOR SERVER WHICH IS ON COMCAST WHEN COMCAST CAME OUT THEY SAID THERE WAS 45 TO 50 VOLTS ON THE GROUND WHAT WOULD CAUSE THIS, THE SERVICE HAS A WATER PIPE AND GROUND ROD GROUND AT THE MAIN AND COMCAST TAPPED OFF THE WATER PIPE.
Posted By: Tesla Re: 50 VOLTS ON GROUND - 02/17/06 03:29 AM
Call an electrician....

Sounds like trouble in your panel.
Posted By: lite bulb Re: 50 VOLTS ON GROUND - 02/17/06 03:48 AM
WHAT WOULD CAUSE THIS
Posted By: Active 1 Re: 50 VOLTS ON GROUND - 02/17/06 04:06 AM
Check the equipment ground on your caps lock. Otherwise call an electrician quickly.... And pay them to make repairs. You may have a dangerous situation that can destroy electrical items, cause shocks, or worse.


Tom
Posted By: dereckbc Re: 50 VOLTS ON GROUND - 02/17/06 04:10 AM
A very common problem. It is life threatening and you should seek professional help ASAP. Sounds like you are not in the trade, so fixing it yourself is not an option.

Failure to get the issue resolved will likely cause immediate equipment failure, and possible fatal shock under the right conditions.
Posted By: Larry Fine Re: 50 VOLTS ON GROUND - 02/17/06 04:12 AM
I am curious as to what point they measured this voltage from, i.e., the reference.
Posted By: dereckbc Re: 50 VOLTS ON GROUND - 02/17/06 02:02 PM
Larry good point. If it was between the service and coax shield guess which pot is calling the kettle black.
Posted By: pauluk Re: 50 VOLTS ON GROUND - 02/17/06 02:42 PM
I'm not clear as the two points between which the measurement was made. I assume one was at the ground on the outlet powering the server, but when you say Comcast "tapped off the water pipe" do you mean that was the reference point used?

If the water pipe is properly bonded and at ground potential, then it might just be a bad equipment ground to the receptacle in question. Or maybe it's a replacement for an older 2-wire outlet which never had a ground in the first place?
Posted By: Radar Re: 50 VOLTS ON GROUND - 02/17/06 02:53 PM
Quote
WHAT WOULD CAUSE THIS
A defect.

Call a qualified service electrician asap.
Posted By: Larry Fine Re: 50 VOLTS ON GROUND - 02/17/06 10:06 PM
Another psooibility is that the problem is on the incoming cable shield, and not the house ground.

Cable systems have, if I'm not mistaken, 50 volts imposed on them for powering in-line equipment.

It is very possible that this damage was caused by a defect in cable-company equipment, and they are liable.
Posted By: wa2ise Re: 50 VOLTS ON GROUND - 02/17/06 11:50 PM
Are some of the light bulbs in the place look too bright, and others dim? Especially when something like the fridge turns on? If so, have an electrician look at the neutral in the panel, etc.

More likely is that there is a bad ground on the computer equipment. Computer power supplies usually have small capacitors from both sides of the powerline to the computer's ground to bypass high frequency switching noise to ground. If the ground doesn't make it to the outside world, the caps will form a voltage divider and impose a voltage close to what you see, around 60VAC. I've seen this blow up digital equipment. But usually the caps are small enough to limit shocking currents low enough to not kill a person.
Posted By: lite bulb Re: 50 VOLTS ON GROUND - 02/21/06 11:49 AM
i had comcast and a electrican the grounding is fine and comcast checked the cable to each unit 2 of the four offices are fine one of the other two offices which is useing a high speed server had 8 volts to ground the other unit had 50 volts to ground comcast checked the cables by putting one lead on the center solid wire of the cable the other lead to the ground rod wire 50 volts this unit is only a tv connect discounted the 3 tvs the line is good connect anyone of the tvs it jumps to 50 volts electrican tested the outlet with a ideal arch and ground fault tester it came up wiring ok ground to net. ok i wouldn't think there are 3 bad tvs i need some input help.
Posted By: resqcapt19 Re: 50 VOLTS ON GROUND - 02/21/06 11:55 AM
If the voltage is on the center conductor of the coax, then it is unlikely that the problem is with the building wiring sytem.
Don
Posted By: pauluk Re: 50 VOLTS ON GROUND - 02/21/06 03:49 PM
So the 50V reading is between the ground rod and the center wire of the coax? I can't figure why the Comcast guy would measure that way. If he was looking for grounding problems I'd expect him to measure to the coax shield/braid.

If the building grounding and bonding has all been checked out and is fine, it sounds as though ot might be a problem on the cable network. Perhaps they're feeding DC power along the cable to power repeaters and a blocking capacitor has gone leaky?

P.S. Didn't think to ask before whether the measured voltage was AC or DC.



[This message has been edited by pauluk (edited 02-21-2006).]
Posted By: hbiss Re: 50 VOLTS ON GROUND - 02/21/06 05:11 PM
First off notice that your keyboard actually has punctuation and a shift key. I really don't have the time to read your giberish 5 times over to try and understand what you are trying to say. You are giving me a headache!

Ok. It wouldn't matter whether they measured from the center conductor or the shield because most splitters have a zero DC resistance from center conductor to shield anyway. So, what's on the center conductor will be on the shield and vice versa. Is it possible that someone used a sat or DBS "power passing" splitter instead of the normal CATV 1000Mhz type? That would be the only explanation for a difference between the shield and center conductor because these splitters do not have a zero DC resistance between center and shield so they can pass power to a LNB or multiswitch.

Sounds to me like the cable service drop is not bonded or not bonded properly to the service ground. Also possible that they are using a VOM that has a high impedance input and would give a false reading unless loaded.

-Hal
Posted By: lite bulb Re: 50 VOLTS ON GROUND - 02/22/06 02:06 AM
i found today a tv in a unit may have been causing a problem, with the tv plugged in and the cable connected, from the center wire of the cable to ground i had 38 volts ac, when i disconnected the tv's ac and cable it dropped down to 6 volts maybe it's the tv i'll find out tomorrow when comcast comes out.
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