I'm getting two conflicting reports and was wondering if anyone can help me. I was told that on the distribution panel, grounded conductors (neutral) and ground wires need to be separated in the distribution panel. The point of disconnect is at the meter and the neutral and ground wires, apparently, have to be separated downstream of the point of disconnect for proper grounding system. Is this true? I got a second opinion and was told that on a 3 wire service to panel, neutral and ground wires are allowed to be terminated on the same bar. Any help would be really appreciated. Thank you all!!
Whoever told you the meter was the point of disconnect was dead wrong. The main panel or disconnect is the first means of overcurrent or disconnect. THIS is where your neutral bond must happen.
Article 250 Grounding and Bonding
II. System Grounding
250.24 Grounding Service-Supplied Alternating-Current Systems
(B) Main Bonding Jumper.
For a grounded system, an unspliced main bonding jumper shall be used to connect the equipment grounding conductor(s) and the service-disconnect enclosure to the grounded conductor within the enclosure for each service disconnect in accordance with 250.28.*
The grounded (neutral) conductor is bonded to ground in one location.
It's common to bond the grounded (neutral) bus and the grounding bus in the panel, but it's not a requirement. The grounded (neutral) conductor can be bonded before the panel, but you'd then be required to keep the grounding and grounded (neutral) conductors separate after that point. So if you bond the grounded (neutral) conductor before the panel, you'll have to pull a separate grounding conductor along with the grounded (neutral) and two ungrounded (hot) conductors.
In most cases the main breaker in the panel is used as the main disconnect, which is why the grounded (neutral) conductor is typically bonded there. If, however, there is a disconnect before the panel. It's likely that, that will be the location where the grounded (neutral) conductor will be bonded. If this is the case, the grounded (neutral) and grounding conductors must be kept separate after this point in the system.
So if the grounded (neutral) conductor is bonded before the panel, you'll have to have 4 conductors from the point of bonding to the panel.
If it is a meter main combo, with an extended service, the neutral and ground must be bonded together at the meter main combo and separated at the interior panel. If it is a back to back service, with only a meter outside and a main breaker inside, then the inside panel must have a neutral and ground bonded together. Sub panels cannot have a relationship between the ground and neutral. If you have a free standing service with a meter main combo, you must drive 2 ground rods at 6 feet apart, and the bonding must happen there. Get it! Got it! Good! I know this because I have an inspector that likes to teach.
If the service disconnect is at the power pole, and for some reason the neutral from the pole to the service entrance becomes broken (which can happen with aluminum feeders etc.), then there is no safe "ground" back to the pole. Any unbalanced current or short would have to be completely absorbed by the house's grounding rods. There could be potential for electrocution if the earth-grounding rods are not up to the task. Old, oxidized/rusted grounding rods might offer more resistance to the short than your barefoot wife's wet hand touching the washing machine. Guess which way the current will go?
"The point of disconnect is at the meter and the neutral and ground wires, apparently, have to be separated downstream of the point of disconnect for proper grounding system. Is this true?"
Yes, that is true because of the above explanation.
"was told that on a 3 wire service to panel, neutral and ground wires are allowed to be terminated on the same bar."
A proper install should have run 4 wires from the meter/disconnect to the service entrance. Ground and neutral are kept isolated from each other from there on. It wouldn't surprise me if they allow three wire installs in a lot of places. Technically, from a physics standpoint, the four wire to main disconnect is safer.
In a 200amp main service most boxes have a jumper from neutral bar to ground. A wire makes a dead short. So everthing becomes one. If you put the ground wire on bus bar as close as you can it still seeing neutral so in english to a garage or a shed you run four wires to hots two nuturals. That balances out the load on two one ten lines equal current transfer thats the way i see it. Insulated and you run five wires put a ground rod in and ground the panel box caseing every one is saying Dont put a wire from ground to shed box from house. The rod is just for lighting any way i dont use one i did a test yesterday with a cellphone charger it will plug in either way so i have four wires in a one breaker panel box in garage 10 thn copper a neutral bar has to tens comming from main house breaker not grounded and two ten guage wires going to two side by side breakers a 20 for outlets and a 15 for lights i split the 220. Now all my plugs i run a third wire to ground on neutral bar it works 15 years radio power tools never blew nothing up i ran this way my charger goes both ways in plug and it works. Now i will rest my case some people on there transformer have on the center tap on pole run a ground wire to neutral. Im big in electronic repair im a ham operator got my tech license. You talk about having tons of grounds well than a neutral wire should be two wires instead of on to balance the two hot sides. Ac current is not dc a ham antenna has ac current comming out a 1500 watt amplifier the shield is just the same size of center conducter if you roll it all up in your hand. Have a nice day