Outlet grounding

[Craigmonte]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

 

[Dennis Alwon]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

You are really asking why do we need a ground. If you hold a drill with a metal case and you touch something that is grounded then there is a good chance when you turn the drill on the current will flow back to the panel as well as thru the casing of the drill thru you and back to ground.

 

[cadpoint]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

No you can't because the bonded ground is for a non current caring conductor, it doesn't exist at the device, there is no suppliment.
The green screw is for an exact application, you are electrify an intended bonded/grounded application, which is a Code Violation.

 

[JohnJ0906]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

Welcome to the forum.

The neutral carries current, the ground - equipment grounding conductor or EGC - does not. If you tied them together at a receptacle, current could flow through, say, the metal faceplate, then a person, to something grounded like a water pipe. Not good.

In an older building, if you wish to replace 2 prong receptacles, read 406.3(D)(3)

 

[richwaskowitz]

Here's why...

Here's why...

Since the grounded current carrying conductor (neutral) at the outlet will be carrying current and it has a measurable amount of resistance / impedance, that means that there will be a voltage drop across that length of conductor. If there is a voltage drop, that means there is a measureable voltage difference at the white wire at the outlet when compared to another ground path, such as metal piping, damp concrete and such. Therefore, a person coming in contact with the neutral and a (different) ground path would feel that voltage drop. If the current were to increase dramatically, albeit for a very short period of time, due to a short within a powertool for example, the voltage drop would also rise, presenting an even greater potential difference to the person holding the tool (if well grounded himself). THAT is one very imporatnt reason for a separate EGC and why sub-panels need to have isolated neutrals. The neutral and ground must anly be connected at one locattion only and that must be at the source. We must remeber that current does not take only the path of least resistance, but takes all paths in different proportions according to Ohm's law.

 

[celtic]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

Objectionable current and effective ground-fault current path.

Have a look at some more graphics over here:
http://mikeholt.com/freegraphics.php?id=gvb

 

[220/221]

can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

It's a rookie question but a good one.

I remember thinking along the same line in my first month on the job. It's not until you understand the whole circuit/system that you can really understand. The neutrals and grounds go to the same place but it's all about how they get there.

Circuitwise, power comes in on the hot and goes back on the neutral. If the neutral becomes disconnected or loose the power will try to get back on the bootlegged ground. Anything plugged in with a ground becomes a conductor.

Recently I read about a kid getting electrocuted from a metal garage door. It is easy to see how this could happen from a bootleged ground and an open neutral.

 

[brian john]

If there is a voltage drop, that means there is a measureable voltage difference at the white wire at the outlet when compared to another ground path, such as metal piping, damp concrete and such. Therefore, a person coming in contact with the neutral and a (different) ground path would feel that voltage drop.

This is inevitable with any load utilizing a neutral and/or grounded conductor and phase/ungrounded conductor. Under normal operating conditions I doubt the average person would feel the potential between the neutral and/or grounded conductor and ground. And not really following how/why this fits into the OP's question other than the voltage exist.

 

[Buck Parrish]

If the neutrals and the grounds are all common at the Main Panel then why (on an old house that didn't originally have a ground at every outlet) can't you just install a jumper from the neutral position on an outlet to the ground position and call it good?

It's 120 volts AC, , Guess what, the AC stands for. Alternating current.

 

[brian john]

It's 120 volts AC, , Guess what, the AC stands for. Alternating current.

And if it was DC the issues would be the same.