Contact a licensed electrician with copious customer feedback. Check AngiesList in your area.
Don't play around with this stuff.
Don't play around with this stuff.
I'm not a licensed electrician, but here's how it was explained to me by a licensed electrician:
There should be only one ground point in your home's electrical system. More than one can cause a ground loop potential. The only other time you would need to drive another copper rod into the ground would be for a roof antenna, and that's to direct atmospheric static/lightning to the ground.
Electrically, the power comes to your house on 3 wires, 2 hot (each 110 volt), the other neutral. The neutral gets connected to the ground lug on your meter pan and the ground/neutral bus bar in your service panel (circuit breaker box). The ground/neutral bus bar also gets bonded (connected by strap) to the cabinet of the service panel. Two forms of earth ground now get connected to the ground/neutral bus bar of the service panel, one appropriately sized wire to the water main where it enters the building, the other to a copper ground rod driven into the ground. I would have to check the current National Electric Code book to see what's done if your water main is PVC.
Every circuit needs to be complete to work. Power coming from the electric company on those hot wires still has to return to the power station for the circuit to be complete. Believe it or not, in some places, it travels though the ground. That's why they call it an earth ground.
All outlets in the house should have the same grounding point; that is to the original neutral/ground bus bar in the service panel. If you run a sub-panel from the main service panel, it too gets it's ground from the same ground/neutral bus bar in the primary panel, you don't ground it to another earth driven rod or more local pipe.
Any structures outside that could be electrified such as a metal fence, swimming pool, or pool pump must also be bonded to the main panel.
All outlet boxes, switch boxes and wires in metal junction boxes get connected back to the original ground as well.
If your house has copper hot/cold water plumbing, a bonding strap is placed at the hot water heater between the cold in and hot out water pipes to maintain continuity between the hot and cold water lines as they become physically separated inside the tank. Example why- if an energized bare wire were to contact an ungrounded hot water line, the hot water line would become energized too. Same kind of recipe for disaster can occur outside, if a bared extension cord were to energize an ungrounded metal fence, the fence would become energized.
In a 110 volt circuit, the black wire is hot, the white wire is neutral and the bare or green wire is ground. The circuit is completed when power flows from hot to neutral once the switch is thrown. The purpose of the ground is to trip the breaker supplying the circuit should any exposed metallic surface (switch box, outlet box, junction box, copper pipe) become energized accidentally; short circuit to ground trips breaker.
Let me give you an example of a near disaster I experienced at my brother's house. He had an outside flood with the hot and neutral wires reversed and no ground. In his situation, the metallic housing for the light became energized by a bared hot wire. Since polarity of the circuit had been reversed, the switch was on the neutral wire rather than the hot wire, and the exposed housing was always energized, even when the switch was in the off position. Had a proper ground been in place, the circuit breaker would have tripped off as soon as it was turned on, because power would flow straight back to ground, a short circuit condition tripping the breaker.
The answer to your question should be you shouldn't need another ground rod if one is already in place. If not, it should run from the neutral/ground bus bar in the primary panel on an appropriately sized wire. If you were to drive another copper rod into the ground, it must be connected to the main panel's ground bus bar. I personally don't see a problem having multiple insertions into earth ground, as long as they are all connected to the same bus bar of the service panel.
If you have a dedicated circuit, make sure it is properly grounded back to the service panel. If it's coming from a sub panel, make sure the sub panel has been properly grounded as described above.
If you connected your dedicated outlet to it's own ground rod and a short occurred, your breaker might not trip so fast. Current will run to ground using the path of least resistance. Imagine what would happen if you took just a hot (black) wire from your neighbor's circuit panel and completed the circuit using the ground and neutral wires from your panel. If a short occurred, your neighbor's circuit breaker might never even trip.
Thank you. I try to pay attention. My best friend growing up became an electrical engineer then a PhD Biomedical engineer. We both had similar hobbies (electronics) and both read the NEC (National Electric Code) book when we bought and redid our houses. Don't ask me why I read that stuff, I have trouble finishing novels, they seem like a waste of time to me.
Electricity is something I have always "gotten". I would recommend a few instruments to every homeowner. First and foremost, a voltage sensor. I call it a "tick". It senses AC volts and beeps when nearby without having to contact the wire. Very useful identifying the hot side of an outlet, the hot wire of a cord, and especially whether or not a circuit is energized. Fortunately, I had mine with me at my brother's before I went up a ladder to change the lightbulb of the outdoor fixture I mentioned. Best of all, that tool is the cheapest, less than $20 gets you a real good one. Never touch a wire without testing it first, the tick is the first tool out. Also makes a great gift. ONLY TESTS AC THOUGH!
I also have a clamp on ammeter/voltmeter and ac line splitter. Not as necessary as the tick, but it helps me identify how much current an appliance is drawing. Both can be had at Sears for less than $100.
Lastly, an outlet tester. Less than $10 and it lets you know if an outlet is wired correctly. Identifies reversed phase and missing ground. Very useful and simple especially if you have an older house where the previous owner did things himself without a clue, like the guy my brother bought his house from. An outlet with a reversed phase is probably the worst thing you could plug something into, unless it's a lamp. Instead of the power switch being on the hot wire, it is on the neutral wire, which means the device is always energized because the power didn't stop at the switch, the switch is now breaking the circuit back to neutral. If you have 2 connected audio components plugged into 2 different outlets wherein one outlet is reversed, you just energized the neutral/ground of everything resulting in hum.
The tester you're talking about is also known as a "proximity" tester. A GREAT tool which everyone should buy if they're working around electricity. Just put the tip next to the wire and it will tell you by a "Ticking" sound and lights whether a wire is energized. (Naturally w/the circuit breaker/fuse not switched off.) Only practical way to tell which is the hot (+) wire in a two-wire nongrounded system. About $10-15.
To enable a breaker to trip, fault current has to flow back to the source (the power company transformer) via the incoming neutral, not the earth. The impedance of the earth by itself is too high. The main purpose of the earth ground is for lightning protection and to stabilize the supply voltage. IMO the use of the term "ground" when referring to the protection against fault current is a misnomer, because in reality, it is the return of this fault current via the service neutral that affords the protection.
I'm pretty sure the subject "ground fault protection" was never addressed before in this thread concerning where to place the ground rod, either on the equipment or on the outlet, nor am I sure it applies. Regardless, the subject "ground fault protection" should be explained further.
Thank you. Very illustrative explanation as to why it would be a such a bad idea to have an outlet connected to it's own ground rod. That's a ground fault easy to understand. Some folks may poo-poo the NEC rules, but they're in place to guard against those "perfect storm" situations and should not be considered subject to interpretation. Thanks again.
If you want to reduce noise from ground loop potentials, just make sure all connected components are on the same circuit and properly polarized. If you mix video and audio, be careful because a lot of noise can come over the CATV cable. In that case you may need an isolation transformer. Aragon used to make one which I think consisted of two 75ohm to 300ohm transformers piggybacked at the 300ohm side. Also make sure your CATV comes from the street to a grounding block, and that the grounding block is connected to the ground of the main service panel. If you have a roof antenna, the pole gets grounded to an earth driven rod and the signal cable from the antenna itself goes to a grounding block, which is also connected back to the main service panel ground. One ground plane means least possibility for a ground loop potential to develop.
If possible, try to run your dedicated line away from noisy circuits or equipment such as motors that could generate noise which could be broadcast into your line. Shielded cable such as Greenfield may be of use as it has 3 conductors (black-white-green) in a metal jacket. The metal jacket would serve as the shield. BX cable only consists of 2 wire (black-white) with the metal jacket serving as the ground and shield. In a noisy environment, I would prefer a ground separated from the shield, such as Greenfield cable.
Surges and pops can also be captured at the service panel by installing a system surge suppressor on the main panel. These help capture noise from the street as well as noise generated within the house from different circuits, such as when a noisy bathroom blower fan or refrigerator switches on or off. In this scenario, the noise travels back to the circuit panel where it is captured before it can travel down another circuit to your equipment. In addition, one of those "Monster Cable" type Power Centers can provide individual filtration and surge suppression at each outlet minimizing component to component noise coming across the power line. Another reason to invest in one of those "Monster" type devices is because they usually have a pretty decent warranty for anything plugged in and protected by them. I would not recommend using a computer styled UPS as I have found them to generate noise and actually degrade the overall sound.