Werid current thru chassis issue

[Ocelot]

I hope this is the right forum to ask this question.
Below is what I experienced last night.
I hope I explained the situation well enough.
I thought I would run it by you guys.

I received some new component video cables and went to hook them up.
I needed to relocate my cable to use the new cables so I started unhooking the cables.
As I was fishing the cables (RCA, digital coax, component, and cable coax) thru the back of my rack, grabbed a hold of all the cables and got bit by current.

Mind you not a lot of current, but enough to make me let go of the cables.
So I did some more investigating, and found 49 volts is coming from the chassis of all my gear, and out the ground in cable line.

For example, if I hold the cable line and touch the cable box, receiver chassis screws, or CD player, I feel current flowing thru my fingers. Enough that I have to let go. I even get it from cables plugged into the back of the TV and receiver when I touch the cable coax (ground).

I have all my components plugged into a Monster HTS 1000.
After testing each piece of equipment plugged in separately, I do measure volts (42-55) from the chassis to the cable coax, but no discernable current.
Only can really feel it when everything is plugged in.

Any Ideas and or suggestions on this issue?
I highly doubt this is normal.

Thanks
Todd

[Gordon Moore]

the chassis of all my gear

That's weird...

I would guess grounding on a piece of gear has been compromised or grounding at the power source has been compromised....start at the wall pug and work backwards....check all your gear power cords for any frays.

Are you using any cheater plugs? (plugs that bypass the 3rd prong (the grounding prong) at a wall plug.

To the best of my knowlege....getting zapped by your gear is not a normal situation.

You may get a better response asking the mods to move this to the DIY area.

[Kevin P]

My guess is that the cable line isn't grounded properly.

Grab a voltmeter, and measure AC between the coax shield on your cable and the ground prong on a handy AC outlet. If you see 45-50 volts, call your cable company and get them to ground the cable line properly.

[Ocelot]

Thanks for the responses.

Gordon,
I'm not using any cheater plugs.
All my gear only has 2 plugs, no ground pin.
And didnt see any issues with any power cords.

Kevin,
I did check the cable line for voltage to ground.
Nadda
That was my first thought also since we had an ice storm here last week.

[Kevin P]

Ok, with your gear plugged in, and your cable TV line disconnected, measure the voltage between the chassis and the ground pin on the outlet. If you see voltage, unplug everything, then plug in one component at a time, and check the voltage again. If you only get voltage with a specific component plugged in, try reversing the plug (if it isn't polarized). Also, check to make sure the outlet is wired correctly. Measure the voltage between each prong and ground. The right (narrower) prong should read 120 or so volts; the left (wider) prong should read zero or close to zero. If it's reversed, or the left prong is showing more than a few volts relative to ground, get your wiring checked.

If the outlet is wired correctly and only a certain component being plugged in causes the voltage, have that component checked out.

[Ocelot]

Ok, I have done some more testing and investigating.
One question first, although.
Does most A/V equipment generate a little voltage/current that under normal circumstances would be dissipated through its neutral side of its plug then to the ground connection of the wall socket?

I’m thinking this is the case.

What I found in my system is that with the TV cable line unhooked from the back of the box, I had no ground anymore. Zero. Zip. The “ground ok” led on my power strip would go out.
Thus when I touched the cable line (my only ground) and a piece of equipment, the circuit to ground was completed and any residue voltage/current would flow thru me.
i.e very little, but still could tell it was there.

With the TV cable line connect to my box which in turn is plugged into the power strip, the “ground ok” led would light, and all voltage/current symptoms dissapperd.

The reason the TV cable is my only ground, is because the ground pin in the wall socket is not wired to ground (no 3rd wire at all). The previous owners must have replaced all the old 2 prong outlets with new 3 prong outlets. As you can guess its an older house.
I discovered this doing the voltage test Kevin suggested.

So that’s were I’m at J

Is my first question above correct?
And second, is it ok to use the TV cable ground as the power strips ground?

Thanks Again
Todd

[Kevin P]

Older wiring (before the early-mid 70s or so) generally has no ground. I'd check the outlet anyway to make sure it's not wired backward. Using the cable coax as the ground or a nearby pipe (heat or water), measure the voltage on the left and right sides of the outlet. You should get voltage between the right side of the outlet and ground, and no/little voltage from the left side. If these are reversed, they could lead to the symptoms you're seeing. In which case you should turn the circuit off and check the outlet to make sure the black wire is connected to the right hand side of the outlet (usually a gold colored screw) and the white wire on the left (silver colored screw). Reverse them if needed. If you're not sure of what to do, consult an electrician.

[Ocelot]

Kevin,

I did measure the voltage in the plug to the cable coax ground as you suggested.
It seems correct.
120V on the little prong, and nothing on the wide prong.
The white and black wires are on their correct side, when I was checking that is when I saw there was no ground wire. 8O

[Kevin P]

Did you try plugging in only one component at a time, checking chassis to the cable ground, to see if it's just one component doing it or all of them?

Also, do any of your components have non-polarized plugs (meaning you can plug it in either way, rather than just one way)? Try reversing any that are that way and see if it makes a difference.

You said none of your components have 3-prong plugs, right? That means they aren't required to be grounded, so I would expect that the voltage is abnormal. Once again, check and see if it's just one component that's the cause.

[whoaru99]

It might not be a bad idea to replace those 3 prong outlets back to the 2 prong style. IMHO it's not a good idea to "think" you have a grounded outlet when you don't.

And no, I do not believe that it is OK to use the cable coax as ground for your gear.

I'd be inclined to think seriously about getting hold of an electrician if you are not a DIY in this regard and inquire about have your existing outlets grounded or running a new, dedicated circuit with a ground. The grounding/non-grounding of the outlet does not seem to be the problem here though. I suspect there is something wrong with one of your pieces of equipment.

I believe I've read somewhere that the threshold for feeling a shock is in the range of 0.5mA to 3mA of current.

As Kevin says - unplug them all and then plug them in one at a time to identify the culprit. Don't forget to test the Monster - who knows maybe that's it.