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In Reply to: RE: Ground and neutral conected posted by SoundMike on June 06, 2007 at 07:45:15
I have seen(heard) benefits from an additional ground.
After checking that all house grounds are good and tight I have driven a new ground rod (at least 8 feet)and ran another ground to my system. I have seen a potential (voltage)difference between the house ground and the new ground when measured with a DVM, usually only a couple of volts. This usually gives me quieter backgrounds. I have done this twice before with good results. It made no difference in the house I am in now.
So it goes.........
Follow Ups:
All ground rods MUST be bonded together. If you have a separate grounding system that is not bonded to your main service ground, there is no avenue for fault current to return to breaker panel and cut off breaker.
To the best of my knowledge this is illegal for residential installations. Did you have a licensed electrician do this? I doubt it.
However, as Kavakid points out, a near lightning strike could have the lightning traveling through you house wiring and causing things like fires, electrical shocks, etc.etc.
But why worry about that? Your property and family are really of no consequence are they?
d.b.
you've had no lightning strikes. Two grounds presents a potential danger that I don't even want to think avout - regardless of other benefits
"Man is the only animal that blushes - or needs to" Mark Twain
I appreciate your remarks and I only want to understand more about this.
I do want to make what I did more clear. The additonal ground is connected to the house ground. All I am doing is providing a better ground.
I my present house there are two grounds, one to the water pipe and one to a ground rod out side. What I have done here is just clean and tighten connections which helped tremendously with background noise.
So it goes.........
It sounds a lot like what EquiTech recommends for a technical ground
I have one installed for the balanced power transformer that feeds my system
Installig a technical ground
Julien
"There's someone in my head, but it's not me"
It sounds a lot like what EquiTech recommends for a technical groundI have one installed for the balanced power transformer that feeds my system
> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >Just so others are not confused the web site and information you supplied is for a separately derived grounded ac power system. The use of an isolation transformer where one leg of the secondary of the transformer is intentionally grounded to earth, thus making it an AC grounded system.
The method given by EquiTech closely matches what NEC 2005 code spells out for the required ac grounding electrode system and bonding wiring method. This wiring method would not satisfy NEC 2005 for a branch circuit fed from the main electrical system.
NEC 2005 clearly states the equipment grounding conductor shall terminate in the same panel as the branch circuit, the equipment grounding conductor is intended for. As stated many times the purpose of the equipment grounding conductor is to return any fault current with the least resistive path back to the source. NEC clearly spells out at the end of a branch circuit the resistance measured from the neutral conductor to the equipment grounding conductor shall not exceed one ohm, (if memory serves me right).... Just a note here, not all cases of fault current, will the current be high enough to trip open the over current device, breaker or fuse. Any fault current leakage will be carried back to the source by the equipment grounding conductor and be seen as a load by the source as well as the electric meter. The main reason for the equipment grounding conductor is safety.
The intent is to assure there will not be a difference of potential, voltage, between the metal cabinet the equipment grounding conductor is bonded to, and any other metal grounded object a person could come in contact with at the same time.
Jim
I sure wouldn't want anyone to get hurt(or worse) because of my post
Julien
"There's someone in my head, but it's not me"
The term "ground" is problematic. Bonding is much better IMHO.
You can have any number of "ground rods". They can be underground utility pipes, ground rods, building steel like re-bar in the ground or steel beams in the ground. But in all cases they must be "bonded" together with one unbroken piece of #8 solid copper wire (as a minimum). This will insure that they are all at equal potential.
Russ
An independent earth connection for the audio system AC "ground" defeats the purpose of the AC "ground" wiring scheme. The purpose is to carry fault current back to the neutral power feed without creating a lethal voltage offset. The kind of fault this is meant to address is inside a piece of equipment with a metal case or metal protrusions that could come into contact with the AC hot and a person. There is resistance in the earth between the independent ground rod and the earth connection to which the AC power feed is connected. Ohm's Law says that fault current that has to travel through this resistance will create a voltage offset, and if the resistance is high enough, this offset might reach lethal levels. This is why the electrical code describes the size of the safety-earth conductor and the requirements for bonding separate earth electrodes.
The second problem is less likely, but more spectacular. Again, it is related to Ohm's Law. If there should be a lightning strike nearby, tremendous current (millions of amperes) will flow through the earth. The lateral component of this current will cause a voltage offset between the two earth electrodes (the original AC power connection and your independent connection) that may exceed the flashover voltage of your AC outlet device, about 6000 volts. Your equipment will see this offset (up to the flashover voltage) between the case and the neutral AC input wire, and may explode or catch fire.
That, is a very bad situation waiting to happen. And the new owners may have no idea.
versed in electricity and codes than I. However - my understanding is that your two grounds can have what is called different ground "potential" and can thus cause a lighting strikc to travel from one to the other. The path could be through the soil or through the house.
If I am incorrect - SOMEONE please speak up.
"Man is the only animal that blushes - or needs to" Mark Twain
I think you are correct. Being the redneck that I am I STILL use CB radios (tube-type thank you very much) for fun and profit. Well, actually not any profit. So far.
So what does this have to do with ground rods and ground wires, etc. Well, my antenna has to be grounded. I had some ham radio geeks help me out with it. Prior to doing this my SWR was 1.9:1 After the new/improved "grounding" arrangement, it is 1.2:1 on CH 40 and 1.3:1 on CH1. Whutzat mean??? It means the antenna (and hence the whole system) is gounded much better .
HOWEVER, that is not to say that what is a good/effective ground for my antenna and mast assy. would be good for the house wiring system. One of my concerns in driving these "ground rods" into the back yard was that they shouldn't be too far apart. Ye Olde Difference of Potential thing.
My arrangement is 5 foot brass rods (1/2" diameter) driven into the ground in a square pattern 4 feet by 4 feet. They're all connected via O-gauge welding line brazed to the rods and then a #4 copper wire goes from the rods to the antenna mast. The length of the #4 copper to the antenna is about 1 foot.
Gooder 'n heck for an antenna ground. Not worth a da** for SAFELY grounding items inside the house. YMMV, but not much.
cheers and 73's
roN
nt.
nt.
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