Got zapped while installing dish

[kevision]

I built a kick a** platform for my dishes (i prefer them on the ground) and while i was repositioning the Dish 500 i got an electrical shock. I was screwing in the screw that holds the dual LNB together, i think it ran against the end of the cable where it meets the LNB output. the current ran through my screwdriver, through me, then to the ground where my knee had contact.
So, to clear up the obvious questions, i was using a Leatherman tool instead of a non-conducting standard screwdriver. and no, my super-platform is not grounded yet. I dont fully understand the electronics of grounding, hence this post. And this was a very low level shock clearly related to the voltage running to the LNB, not some bizzare house current short or something.

If i ground the dishes, wont that set up the right conditions to kind of galvanize the RG-6 cable? It gets very very wet here. If i sealed all exposed connectors would this cease to be an issue?

I know that all installs should be grounded for lightning at the very least, and i most of the fun of satellite TV is watching it, not standing in the back yard holding the LNB, but im concerned im missing something obvious here.
thanks for any suggestions.

[retiredTech]

are you sure your house ac outlet that the receiver is connected to is polarized correctly?

[drjake]

The receiver powers the LNB with as much as 19 volts. Thus, if your receiver was plugged in, it is not inconceivable that you would receive a shock if you touched the center conductor of the coax.

[Mike500]

The situation occurred because the system ground is faulty or the neutral and ground has been improperly connected together in a sub-panel, and/or the ground screw and neutral are wired together

In the power industry, wiring the neutral to the ground screw is called a bootleg ground. There is only one tester that will tell you that this situation is present in an outlet, without removing the outlet.

The $2 three prong tester will not detect this situation. The Ideal SureTest tester ($200 plus) is the only tool that will identify this situation, without removing the cover plate and inspecting the connections.

If you are installing a satellite system and have a coax that has been grounded to a secure ground, your best way af testing for a "bootleg ground" or a floating ground is a DMM (digital multi-meter) set on the AC voltage setting. An inexpensive one costs about $20, but make sure that it is marked "double insulated." I prefer one that is auto-ranging.

Set the DMM on AC voltage. If it is not autoranging, set it at 0-250 volts. Do not touch the tips of the leads. Put one lead into the wider "neutral slot" on the receptacle. Place the other lead on the outside "shield" connection of the "F" connector.

If you see a voltage more than 10 volts above or below 120, that is 75-150 volts, you have a "bootleg ground" with another situation called a "floating ground."

Basically, the electrical system's main ground is disconnected or faulty, and the neutral has been connected to the ground screw.

Placing the leads on the neutral and hot cavities of the receptacle will result in a voltage reading of between 75-150 vac.

This problem often occurs, when the neutral and ground wires are wired together in a sub-panel. These wires "can" be wired together in a main panel, but NEVER in a sub-panel.

Contrary to conventional wisdom, NEUTRAL is NOT GROUND! It is a LIVE RETURN WIRE. A GFCI will NOT protect you from a LIVE neutral.

[RJS1111111]

A DC shock can feel worse than AC, because it can cause your muscles to painfully contract or cramp.

I would also strongly advise checking (with a multimeter in dry conditions) for any AC line voltage that is "hot" to ground. As I'm sure you're aware, that could easily kill you.

Although your platform is not electrically "grounded", it is most likely not electrically insulated from the ground either. It will provide a path to ground for AC line voltage or lightning, especially under wet conditions.

Dishes should be grounded, not to protect the electronics (lightning will fry them anyway), but to give people some added protection from electrocution and fire.

[Mike500]

The situation Kevision mentions has nothing to do with getting a shock from 19 VDC. He got a line voltage AC shock, since he became the "neutral" return leg of a 120 volt AC circuit.

In the case of a floating or bootleg ground that I previously mentioned, there is no ground return to complete the circuit for one phase of the AC circuit. Kevision has become the neutral wire.

The wide prong of the polarized plug is connected to the neutral wire at the recepatacle and to the metal case of the receiver. It is then connected to the shield of the coax. In the case of a floating or bootleg ground the ground does not complete the circuit to earth. Kevision became the return wire or neutral for the circuit. In that case, he was shocked by 75-150 VAC.

[kevision]

Thank you very much for this information. Im going to focus my attention on the electrical system as it may not be grounded or is damaged. Please note that the shock occured from contact with the OUTSIDE conductor of the coax, not the center coax. on the DISH 500 LNB, one of the screws rubs up against the end connector of the coax. so that lends credence to Mike's theory. That also means that if the floor were ever wet or something, i could get a similar shock just from touching the reciever. EDIT: and i should note that i was overconfident in my first post that it was simply the LNB power that got me, i assumed house current would be more painful. But perhaps i was spared a bit by the 100ft run of RG-6??

time to get the multimeter and possibly an electrician.
thanks again

[Mike500]

I cannot over emphasize the importance of a good grounding system.

In my own 1996 built house, I installed a dbs system in 1997. I installed a separate grounding rod and bonded it with a 6 gage solid copper conductor to the main 4 gage conductor running from the meter base to the original grounding rod. To my amazement, I dug up the connection of the original main grounding rod and found out that the original electrician used a zinc not approved for direct burial grounding clamp. The grounding clamp corroded off after no more than two years. Along with the acidic soil, the zinc became an anode for a copper/zinc battery.

The most common mistake made by amateur and inexperienced electricians is that they equate NEUTRAL as the same as GROUND. They are not! Neutral is the POWER RETURN CONDUCTOR. The only place, where they are connected together is at the MAIN PANEL. Anywhere else; it is dangerous.

[gilswitch]

if it were connected to the reciever you will get a little shock every time.ther is something running through tha line?it is the worst when you are standing on your ladder and it happens.

[RJS1111111]

if it were connected to the reciever you will get a little shock every time.ther is something running through tha line?it is the worst when you are standing on your ladder and it happens.If everything is okay, there is only up to 19 volts DC on the coax. This should not give you any shock, unless you touch both inner and outer conductors at the same time. Even then, if it is touching dry skin, there should be no sensation of a shock. Of course, it's easy to get jabbed with those tiny shield wires, which could boost your conductivity, as well as hurt like the dickens.

Based on the above discussions, if I were you, I'd check for any AC potential to local ground or mis-wired neutral, just to ensure that "little shock" doesn't get a chance to kill someone.