grounds and neutrals

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From a NEC stand-point, because 250.23(A)(5) prohibits any connection between the grounded
conductor and grounding conductor other than in the 1st (service) disconnecting means
 
To make a separation at the meter where the POCO delivers a grounded conductor, you would make that conductor the neutral and use a ground rod for the grounding conductor? All test show faults need to return to source on the lowest impedance path possible and a ground rod does not supply that path. When you leave that panel with four conductors, the grounded and grounding conductor are connected at the same point in the panel under the meter. IMO.
 
enireh said:
if there is only one panel and it is at the meter do the grounds need to be separate from the neutrals? if not, why?
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I think what you're really asking is why is it important, not what the rule is. One thing is that at the meter there is no separate ground and neutral. They are bonded there. Then the neutral/ground travels with the phase conductors to the main breaker. Right there is the last place they are allowed to be one and the same. After that the circuits branch out. Grounds and neutrals inside that panel can be connected because they are going to connect to the same conductor inside that same panel anyway.

Once you leave that panel, if your neutrals and grounds are shared you will have current traveling on your ground wires back to the main panel. That means that any energized equipment that has bonded metal has the potential to find a ground elsewhere. That may be another piece of equipment that has bonded metal, or even a copper water pipe in the area, etc.

This is a basic explanation. Somebody can explain it more technically, but due to the way your question is worded I felt this was a reasonable way to put it.
 
jaylectricity said:
I think what you're really asking is why is it important, not what the rule is. One thing is that at the meter there is no separate ground and neutral. They are bonded there. Then the neutral/ground travels with the phase conductors to the main breaker. Right there is the last place they are allowed to be one and the same. After that the circuits branch out. Grounds and neutrals inside that panel can be connected because they are going to connect to the same conductor inside that same panel anyway.

Once you leave that panel, if your neutrals and grounds are shared you will have current traveling on your ground wires back to the main panel. That means that any energized equipment that has bonded metal has the potential to find a ground elsewhere. That may be another piece of equipment that has bonded metal, or even a copper water pipe in the area, etc.

This is a basic explanation. Somebody can explain it more technically, but due to the way your question is worded I felt this was a reasonable way to put it.
Click to expand...
To add to what you said - once you are past the main or system bonding jumper location, the "grounded (most often is a neutral)" and "equipment grounding" conductors must be kept separated from one another.
 
enireh said:
if there is only one panel and it is at the meter do the grounds need to be separate from the neutrals? if not, why?
Click to expand...
I am just going to answer the why part.

A ground conductor (terrible name because it implies earth is involved somehow and earth has nothing to do with it) should not have any normal load current imposed upon it. If there was current flowing there would be a voltage drop developed along its length. In a large facility where circuit lengths can be very long, it is possible that you could develop enough voltage on a ground conductor to electrocute someone who touched the chassis of grounded frame. The chassis or frame would have voltage on it.

You can clearly see this with about any circuit with a load on it. At a distant receptacle of branch circuit panel just measure the voltage between N and G conductors. The voltage you see on the Neutral is the result of current flowing on the neutral conductor. In addition you can also feel the problem. Just go to an older home with a Electric 3-wire Dryer. Start the dryer up, then take one hand on the dryer, and another on the washing machine.
 
grounds neutrals

grounds neutrals

jaylectricity said:
I think what you're really asking is why is it important, not what the rule is. One thing is that at the meter there is no separate ground and neutral. They are bonded there. Then the neutral/ground travels with the phase conductors to the main breaker. Right there is the last place they are allowed to be one and the same. After that the circuits branch out. Grounds and neutrals inside that panel can be connected because they are going to connect to the same conductor inside that same panel anyway.

Once you leave that panel, if your neutrals and grounds are shared you will have current traveling on your ground wires back to the main panel. That means that any energized equipment that has bonded metal has the potential to find a ground elsewhere. That may be another piece of equipment that has bonded metal, or even a copper water pipe in the area, etc.

This is a basic explanation. Somebody can explain it more technically, but due to the way your question is worded I felt this was a reasonable way to put it.
Click to expand...

thank you so much!
 
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