Only in your primary service panel should neutral and ground be connected together. That appears to be the one connected to your meter in your case. Secondary panels should have neutral and ground bus bars that are independent from one another. Bonding ground and neutral in other areas of your home appears to have no effect on functioning, but it is a safety issue. Make sure you don't have any exposed metal parts where someone might be tempted to connect these wires together.
In conclusion, neutral and ground should never be bonded together inside your service panel nor anywhere else for that matter. This could cause serious damage to your wiring which may require replacement if not detected and repaired early on.
The neutral bus bar is connected to the ground at the service panel (just at the service panel—this is critical). As a result, the ground lead and neutral should be connected to the same bus (the neutral bus bar). Any sub-panel following the principal service from there, however, MUST have an isolated neutral. This would include any branch circuits in a secondary panel.
In other words, if you're not sure whether or not your system is single-phase or three-phase, take note of where the neutral bus bar connects to the ground. If they're the same, then you've got a three-phase system. If they're not, then you've got a single-phase system.
Here's how a single-phase system would look: The black leads are always hot, while the white lead is neutral. There's only one set of hot and neutral wires per circuit. Because there's no way for these wires to be confused, they can be any size you like.
A three-phase system looks the same, except that there are three sets of hot and neutral wires per circuit. These could be large enough to fit through a wall socket, or they could be as small as 14 AWG wire. It depends on what kind of load you expect to be connected to the circuit.
In either case, the neutral bus bar should be connected to the ground at the service panel.
However, connecting the systems at several locations might result in "objectionable currents" and something known as "ground loops." As a result, they are linked at one and only one point-the main service panel. This is why they were linked at the time. If you connect multiple links of cable to different parts of the circuit, there will be no current flowing through any of them, and therefore no way for them to share a common voltage.
The reason these connections are made at the main service panel is because that is where the utility connects to supply electricity to the rest of its network. By linking the panels together, any electricity that flows through one portion of the system cannot flow through another part of the network; it must go back to the source. This prevents two separate circuits within your house from feeding power back into each other, which could cause damage to your property or worse.
In addition, making these connections at one location reduces the chance of an electrical problem arising with one section of the network while another section remains active. For example, if you had both a hot and a neutral wire connected to a device such as a heater, then something like a short would cause damage to that device even if the other wire was not used. By linking the networks at one location, this problem can be prevented since neither line can provide power to the heater.
The neutral bus bar The bar connects to the main service neutral and returns the current to the power grid. The neutral bus bar, which also functions as the grounding bus bar in many service panels, is where the individual bare copper circuit ground wires are terminated. It should be either metal or plastic and should not contain any wood or other non-conductive material. If it does, you will need to replace that part.
There should be one neutral bus bar per circuit panel. If there is more than one, each additional neutral bus bar provides an additional place for electrical noise to enter the system. This can cause problems with equipment that depends on having a fixed electric potential, such as digital cameras and monitors. For maximum reliability, only use single-piece neutral buses that connect directly to the chassis of the panel.
If the neutral bus bar is made of metal, it should be connected directly to the chassis of the panel. This prevents electrical noise from entering the panel through the metal frame surrounding it. If the neutral bar is connected to the frame instead, some of this noise will be allowed into the panel.
The neutral bus bar should be located near the center of the panel, between the hot and ground bars.
The service panel is the only area where neutral and ground may coexist (your disconnect outside). In a subpanel, the neutral and ground must be separated (floating). There are other threads on this issue on this MB. The feeder conductors and service conductors should have the same size. If they don't, then you have a problem that needs to be fixed by a qualified technician.
The wiring of the house must allow for easy separation of these wires if necessary. For example, if there are places where aluminum wire is used for exterior services and it cannot be easily removed from the copper service conductors, then those areas must be ganged (grouped) together at the main panel. This prevents any confusion at a later date when changing out conductors or adding new circuits.
The main panel is the only location where all three conductors can be found on one circuit breaker or fuse. If other outlets need power, then they must also be ganged here. Ganging equipment such as lights or heaters without their own switch or receptacle will waste energy since these devices are always on unless specifically turned off.
Grounds and neutrals are welcome in the same bus bar. Under a screw, however, only one neutral wire is permitted. There are no additional neutrals or grounds allowed to be beneath the screw. If you're not sure if your home was built with separated wires, call your local utility company before you start work.
At the point of supply, the neutral conductor is linked to earth ground, and equipment cases are connected to the neutral. If any equipment has a leak or an insulation issue, a broken neutral connection can cause all of the equipment cases to increase to a lethal voltage.
At the point of use, the neutrals from each house are joined together with a cable that runs along the street to a panel box near one end of the line. From there, it's fed into a distribution center where it gets split up again into its component parts and sent to each house. In some regions, they call this a "shared neutral" system; otherwise known as a "three-wire system". In other words, each home receives two sets of wires - one set for live power, another set for dead power. The third set is used by both systems to keep track of who owns what wire.
In a four-wire system, there's also a fourth wire called a "grounding conductor"; which is used to connect all equipment sheds to earth ground. This is different from house to house; but rather, it's done at the main distribution center.