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User107681 03-09-2011 04:40 PM

Electrical
 
Hi my name is Al I am new to this forum . I am a home inspector and see this on ocassion. The netural circuit wires are connected to the same grounding bar I know this is unsafe and need a clarification as to why. I think I Know the answer but need to confirm.

a7ecorsair 03-09-2011 05:00 PM

Perfectly fine in a main panel but not OK in a sub panel.

rjniles 03-09-2011 05:15 PM

Quote:

Originally Posted by Al Pirro (Post 606108)
Hi my name is Al I am new to this forum . I am a home inspector and see this on ocassion. The netural circuit wires are connected to the same grounding bar I know this is unsafe and need a clarification as to why. I think I Know the answer but need to confirm.

You are a home inspector and do not know when the neutral and ground must be isolated and when not. Don't inspect my house!

davido30093 03-09-2011 06:03 PM

And you are a home inspector where?

Jeter 03-09-2011 06:53 PM

It's definitely a SAFE thing, if anything (hot) ever went to ground it would trip. If anything (hot) ever went to neutral it would only trip if the neutral/ ground WERE connected ( bonding strap ) . If not connected the neutral would stay energized, ( which you don't want ). Any sub-panel should not have bonding strap or bonding screw, ground & neutral should be isolated. Just main panel requires it.

Jim Port 03-09-2011 07:05 PM

Please spend some time shadowing an experienced inspector or take some educational classes. With statements like you made you are showing that you do not have the knowledge or experience to properly inspect a property. You are doing a disservice to both the HI industry and any homeowner that you take money from.

SD515 03-09-2011 07:27 PM

Quote:

Originally Posted by Jeter (Post 606195)
... If anything (hot) ever went to neutral it would only trip if the neutral/ ground WERE connected ( bonding strap ) . If not connected the neutral would stay energized, ( which you don't want )...

Not true Jeter. You don't need a ground wire at all to blow a fuse/trip a breaker on a line to neutral short. The current gets back to the transformer via the neutral wire. A line to ground fault uses the ground wire to get back to the service disconnect, at which point it transfers to the neutral to get to the transformer.

Just FYI

Jeter 03-09-2011 08:32 PM

Just wondering what the purpose of a ground plate or rods are if your saying a hot to ground goes to panel, transfers to neutral bar then to transformer through neutral to trip. I thought the reason for the plate or rods is so that if a hot to ground or hot to neutral shorts out, it takes the shortest route , which is the plate or rods, therfore it dosent take the path to the transformer, which is also suppliying other houses or whatever. What u are saying makes total sense, just wondering if u have an answer, interesting how grounding and bonding works , thanks

Jim Port 03-09-2011 08:48 PM

Jeter, you do not need a ground rod or plate in order to have a properly grounded receptacle or to trip a breaker. Grounding electrodes are for high voltage events like lightning.

a7ecorsair 03-09-2011 08:59 PM

Jeter, keep this in mind. Current has to return to its source. If I took a flashlight and connected a wire to the spring that contacts the battery and stuck this wire in the ground, the flashlight will continue to work and there will be no current flowing though the "ground wire".

Jeter 03-09-2011 09:09 PM

Right, i totally agree that it has to return to it's source, but since the main ground from the source is through the neutral, would the ground plate just take smaller shorts ? And if it's to extreme , would the neutral take the bigger short through the neutral to the pole , blow the fuse ?

a7ecorsair 03-09-2011 09:24 PM

The ground isn't even needed for your house electrical to work. Let's make a change to your house wiring.
The transformer feeding your house has three wires that connect to your main panel - two to the bus bars and one to the neutral/ground bar. The power company has temporarily removed the ground wire that goes from the transformer center tap to ground.
We will remove the #6 copper ground wire that goes from your main panel to the ground rod.
Guess what, everything in the house is working just fine including all the GFCI's.
If you were to short a hot to ground the breaker will trip. If you overload a circuit the breaker will trip.

AllanJ 03-09-2011 09:32 PM

Earth is not that good a conductor. There is a ground rod or ground plate or underground water pipe connected to (bonded to) the main panel combined neutral and ground bus (generally via a #6 copper wire). There is a ground rod or plate at the utility pole bonded to the transformer neutral. Normally very little current flows between those two ground plates owing to the resistance of the earth in between but rather almost all of the currrent goes out the combined neutral/ground wire in the service drop. Should the "main" neutral be broken, more than a couple of amperes having to use the earth as a return will result in a significant voltage difference between neutral at the panel and neutral at the transformer and brightening/dimming of lights in the house become noticeable. The voltage difference between any two points in a circuit always equals the current flowing between those two points times the resistance between those two points. With a good neutral in the service drop, the voltage difference beween the transformer neutral and the panel neutral is small, maybe just one or two volts. Then the amount of current that took the earth route between the ground plates equals that voltage difference divided by the resistance of said alternate route which quotient is also very small.

Jeter 03-09-2011 09:39 PM

Right, that's what I was asking, if u rely on the neutral going back to the transformer, my original question was , why have a ground plate if your relying on your neutral ? And in the panel if the bonding strap from neutral to ground is removed, hot to ground wouldn't trip ? So why is it that u need to run a #6 from plate to panel when doing a service for it to pass? Must do something.

Jeter 03-09-2011 09:45 PM

They wouldn't want every short relying on the main neutral in residential, the #6 would take it to the plate unless theres a big short where the amprage exceeds the panel rating, (barley happens) then the neutral would take It, right? Just wondering,


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