ECN Forum Forums General Topics of the Trade General Discussion Area 50 VOLTS ON GROUND

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.

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.

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

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).]

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

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.