HDTV Forum

Grounding

Grounding can be a very complex source of problems and life threatening hazards. Figuring out whether this is something you can resolve yourself without injury or if you need a professional can be difficult. The key to most problems is multiple ground points and this may require the use of an adapter to prevent the third pin, ground, from being connected or a device which isolates an antenna cable input ground from your system.

Commercial, Industrial Equipment

Grounding in these cases is typically about safety and it is imperative that it be done correctly or somebody could be injured resulting in legal damages that your insurance may not cover. Bypassing the grounding pin is not recommended. I am talking about refrigerators, mixers, temp controls, microwave ovens, sump pumps, AC and DC drives, etc. If a piece of equipment supports the third pin you better use it. If this is causing a problem get an electrician, you need professional help.

Professional Equipment

Grounding in these cases is typically about noise. Defeating the ground pin on these products should not cause safety problems but this could affect signal to noise ratio within the system. It is not common to have grounding problems with this type of equipment since most of it is designed to properly use the AC ground circuit.


Consumer Equipment

Most consumer products do not support the third grounding pin. For those that do there are varying ways manufacturers apply this circuit to their products. Unless you have a satellite or cable receiver this is typically not a safety issue but defeating the ground pin could increase noise in the system as well as improve it. This will depend on how the ground was designed into the equipment and what your application is. Many products with a ground pin also use an AC input PIE filter to prevent contamination of noise from either the product or the AC source. Just because a product has such an AC cord and input jack on the back means nothing without opening the product and inspecting the AC input to see what is really in there and how it is being applied. Often times the ground pin is tied to the case of the product which unfortunately is also tied to the actual circuits within the case. Professionally this is wrong unless there is a switch to disconnect the ground pin from the case or the circuits from the case.

Surge Suppressors, Lightning Arresters, Line Conditioners, AC Synthesizers

Defeating the ground pin on these devices will defeat the very purpose they were intended for. DO NOT defeat the ground pin on these products. One more time, DO NOT defeat the ground pin on these products.


Computer Equipment

Do not defeat the AC ground pin on computers. Computers are great at generating RF noise that can interfere with other products in your home. That is what that sheet is all about with the FCC codes and warnings that you get when you buy one from a turn key retailer.


Trouble Shooting Safety

When you work with grounds you must follow the old rule of one hand in your pocket and rubber sole shoes such as tennis/sports shoes. Electricity kills you by running across your chest area based upon what two objects the two parts of your body are touching with the most common being hand to hand or hand to leg. So when you remove a cable DO NOT touch something else with your other hand while unscrewing it; One hand in your pocket. I have been shocked numerous times throughout my career doing nothing more than making me know I am alive and grumpy. Only one time have I been severely electrocuted and I

Hi Richard,

Actually my problem is a 60 cycle hum. None of my components
have three prong plugs, in either my main room or my bedroom including
the cable boxes. The only three prong plug I have is on the surge units
which are Panamax. I have a three to two adaptor from the Panamax to
the wall but both the adaptors have grounds on them which could also be
a problem. The sixty cycle hum is causing 2" lines that run through the
picture. Any suggestions let me know, it drives me up a wall.

Thanks,

Anthony

I have heard of such noise being caused by refrigerators, intermittently as it only occurs when the compressor is running. Where to start?

Either your AC power coming into the house, an AC product in your house or even possibly the ground for your cable or satellite may be your problem. Defeating the ground on your lightning arrester is not recommended as it will not work.

First step is to read through the grounding article here and make sure that is not your problem.

Next step is to isolate the display from the rest of your stuff in the house. If you can see this on a non used input then we can cut to the chase real quick. Make sure the video mute is turned off so you get a black raster and turn up your brightness so you can see the black and hopefully your noise bars. Disconnect everything from the display and see if the bars go away. If they do not then you clearly have an AC noise problem. The next step is to go to your breaker box and turn everything off except for the display AC. Go into the room and make sure that everything else is dead and if not unplug products until they are. Due to the way houses can be wired it is recommended you check every room in your house just to be sure that the only active circuit in your house is the AC power coming in and feeding the display. If you still have the noise bars then it is the AC power coming into your house. You can use either an AC conditioner or AC synthesizer with the synthesizer being a sure remedy for your problem and also the more expensive solution. If you try the conditioner route be prepared to try various brands and models at many price points and make sure you can return it if it does not work. You will be looking for the one that has the right kind of filtering to resolve your problem and you won