Atlanta Home Inspection-certified member ICC,

Unless your home was built over a half a century ago, the elctrical power feed to your home has three wires which come from the power company's line transformer.One of the wires is the common or neutral.The other two wires are"hot" and each of them has 110-120vac.The three wires comes through the power company's meter to the main power panel in your home.

THE MAIN POWER PANEL

The main power panel is usally a large metal box containing a main power switch and circuit breakers(or fuses).In the main power panel or load center the main line is divided into a few 230vac branch circuits and many 115vac branch circuits.Each branch circuit is protected from overload by either a fuse or circuit breaker which opens the circuit when there is to much current.Although a fuse and circuit breaker does the same thing,a breaker is better because it can be reset after being tripped.A fuse has to be replaced.The main line(service feeders) common wire is connected to the ground bus in the main panel.The white wire(neutral) is connected to the ground bus.The neutral for each branch circuit leads  back to this ground bus.The black wires(hot wires) are connected to the overcurrent protection fuse or breakers.

1. Aluminum single conductor wiring on 120-volt circuits 
2. Broken fixtures or devices 
3. Loose or inoperative ceiling fans 
4. Double tapped circuits in service or distribution panels 
5. Permanently installed extension cords or temporary wiring 
6. Frayed, deteriorated or melted insulation 
7. Missing or inoperative GFCIs 
8. Grounds loose, wire connections/clamps corroded or not properly connected 
9. Improper junctions or splices 
10. Improper main disconnect 
11. Improper exterior wiring 
12. Loose outlets and switches 
13. Knob and tube wiring (age and condition concerns) 
14. Lights not functional 
15. Missing cover plates 
16. Outlets with open grounds 
17. Inadequate overhead cable clearances 
18. Oversized breakers or fuses 
19. Inoperative smoke detectors 
20. Reversed polarity at outlets 
21. Unsecured or inadequately secured electrical cables 
22. Subpanel grounds and neutrals not separated 
23. Missing knock out in panel/boxes 
24. Bath lights on GFCI circuit

National electrical code{250-50}Electrode Grounding SystemAt the service panel,the enclosre(box),the incoming neutral conductor,and the grounding elctrode conductor(ground rod).
The grounding elctrode system must all be bonded together toform a complete EGS.The conductor that connect from the service equipment to the grounding electrode are referred to as grounding electrode conductors.This MUST connect,directly or indirectly,to the incoming neutral service conductor inside the panel.This connect in some parts of the country the
ultility companies prefer to see the connection inside their meter socket.#4 copper used with acorn clamp and connect  200amp service.

NEC code{250-50a2}
Metal water service(water pipes at water heater are in contact with metal even when cpvc is in use)piping in contact with earth 10 feet or more must be included as part of Electrode Grounding System.

NEC code{250-50
Requires that connection to metal water pipe electrodes be no further than 5 feet where pipe enters the building.If the water enters the home on the opposite side where electrical system enters,then a wire is supposed to run over to the place where the water enters the building,instead of just picking up at a point near electrical service.

NEC code Grounding rods{250-52c}
Local building jurisdictions require driven rods regardless of what other electrodes are present.Most common size for residential 1/2 rod 8ft long.

Main bonding jumpers can take many forms.In some service equipment,the neutral is bonded in such a way that no other connection is necessary,and there is no way for it not to be bonded.Such load centers(main Panel) will be labeled "suitable for service equipment only."

Panel bonding-might be in the form of a strap(tie bar),screw(green),or a wire connecting to neytral bus and panel enclosure.In some panels there is only one neutral bar,and grounded conductors and grounding conductors are both connected to one bar.In other panels there are separate bars for the grounded and grounding conductors.When this is the case the separate bars must bond together.

*Grounding Electrode Conductors-connect equipment to earth. *Equipment Grounding Conductors-connect equipment to the incoming
neutral theough main bonding jumper *Boding Conductors-connect equipment to equipment,or in residential
the main bonding jumper to equipment to the service neutral.

Power comes directly from the electrical company's power line, through the electrical meter on the outside of your house and into the electrical service panel. The "Main" circuit breaker is often called a "Double Pole Service Disconnect" and is what controls the live power from energizing the circuits in the electrical panel. It's easily recognizable as it has two thick black wires feeding it from the electrical meter and consists of two circuit breaker handles joined together. The Main is used to power all the circuits on or off at one time.
The Main circuit breaker also identifies the amperage capacity of the electrical panel and will have a number on it identifying its amp capacity such as "100" or "150". 100 amp service is the minimum allowed by code today, with 150 amp being very common.
The two thick black hot service wires feeding the Main each carry 120 volts from the electric meter and feed the two "Hot" electrical bus bars in the panel. These bus bars provide power to the circuits. By varying how many bus bars a circuit breaker connects to, that determines if it is providing 120 volt or 240 volt electricity to a circuit. Single pole circuit breakers provide 120 volts and connect to just one hot bus bar. Double pole circuit breakers provide 240 volts to a circuit and plug into both hot bus bars. The electrical current leaves the service panel through the black power wire and is on its way to your electrical device.

Once the power leaves the electrical service panel through the black wire and does its work through the electrical device (light bulb, motor, etc.) the electrical current  returns back  to the service panel through the Neutral circuit white wire which is connected to the Neutral bar.
The Neutral bar is attached to the service panel and collects all the neutral white wires from the various circuits. The bar connects to the main circuit neutral wire where it returns the current back to the electric utility company's transformer, usually the source of the electricity.The main house Grounding wire also connects to the Neutral bar thereby grounding the circuits to an earth ground directly via ground rods or by attachment to a metallic cold water pipe.The Grounding bar may be part of the Neutral bar or separate.It collects all the Ground wires from the various circuits and ties back into the Neutral bar.
The circuit breaker is designed to be the weak link in your electrical system. But that's a good thing as it's designed to fail safely. When a circuit draws more current than it is designed to handle, the wiring gets hot and problems can occur including fires. That's why excessive current in a circuit is prevented by the use of "overcurrent" safety devices such as the circuit breaker. Circuit breakers connect to the Hot bus bars and come in a variety of types and capacities.
Single Pole Breakers provide 120 volts and typically come in ratings of 15 amps to 20 amps. These breakers make up most of the breakers in your home.
Double Pole Breakers provide 240 volts and come in ratings from 15 amps to 50 amps. These breakers usually serve dedicated circuits for large appliances such as electric dryers, stoves, air conditioners, etc.
Ground Fault Circuit Interrupter (GFCI) Breakers protect an entire circuit from ground faults unlike the GFCI outlet which only protects at that location. With a GFCI Breaker you do not need local GFCI's. These are typically used on circuits where the likelihood of fatal shock is higher, such as bathrooms and can stop current flow within 25 milliseconds when detecting a ground fault condition.
A fault in the Ground condition where the Hot power wire (black) touches the Ground wire or a grounded metal electrical device box.