"married to the equipment gnd"

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Old 07-16-02, 04:27 AM
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"married to the equipment gnd"

"married to the equipment gnd bar"

Does this mean to connect the equipment gnd bar to the neutral bar?
 
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Old 07-16-02, 06:34 AM
J
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It means something is to be connected to the grounding bar. It's a stretch to try to infer what this something is without more context.
 
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Old 07-16-02, 10:43 AM
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"married to the equipment gnd bar"

Under no circumstances should connect the neutral bar and the grounding bar together except at the main panel. You might try to provide more detail information about your question.
 
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Old 07-16-02, 01:51 PM
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except at the main panel

Sorry folks, I was referring to this as it applies to the main service panel. I guess I thought it was a phrase that didn't need any more context. Married=connected, united, and so on. Just wanted to make sure I was understanding it correctly as it applies to house wiring.
I still have a problem understanding this since both go to same ground stake in the earth, right?
Example- the purpose of a 4 wire 220 volt appliance cord is to seperate the ground from the neutral to lessen the chance of electrical shock, right? But both wires are actually still connected at the service panel since they both go to the sam ground rod in the earth. Heheh, I think the explanation for this is going to be a little over my head, if we start talking about impedance ( is that the word ?)and such. If so, maybe I will research it a little.

Tx
 
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Old 07-16-02, 07:36 PM
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IN laymen's terms you are right but you are wrong. YOu would have been better said if you had said that in the main service rated panel the neutral bar and the grounding bar are married together so that they both are going to the center tap of that transformer where the power originally came from. While the ground rod is also connected to the same location as the service neutral conductor in the main servece rated panel that is coming from the zero point of the transformer between the two hot phases providing power to the house, that grounding rod is not much of an electrical path except under extreme high current situations such as a lightening strike or dead short condition. The electricity will take its easiest path back to its source which would be a much better and easier electrical path back to the center tap of the transformer where the power came from than through a ground rod that would have much less a conductive path. Electricity will take its easiest path.

While I mentioned the ground rod comes into affect during a short circuit condition even then the path to the center tap of the transformer is the easiest path. The ground rod may take some stray current of that massive short circuit condition yet the center tap will take the biggest share of that shorted current.

If lightening strikes with enough power the centeral tap of the transformer [neutral source of power] will become overfull of current then the ground rod will hopefully obsorb some of that massive power produced by lightening which would be a new source of power not normally coming from the windings of the transformer.

While it is true that the neutral and grounding are married in the main service panel little if any current from the neutral bar goes up stream through the branch circuits from the panel into the house wiring. Again the current of the neutral will take its easiest path. The path to the center tap of the transformer would be much easier than upstream to through the house wiring.

Tried to stay in laymen's terms so that it may be more understandable what is happening in the above conditions staying away from technical jargon.

Maybe others will have a better way of saying it so you can understand the principle of what you are asking.

HOpe this helps

Wg
 
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Old 07-16-02, 07:59 PM
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Wg pretty much covered everything, but I'll throw in my two cents.

First of all, the grounding rod has absolutely nothing to do with this discussion, so just forget it. It's a whole different subject.

The root of the question is why we even have equipment grounding wires in the first place, and why we don't just use the neutral for that purpose. Equipment grounding wires are so that you don't get electrocuted when you touch the chassis of an appliance. To do that function, it is important that these wires not carry any current under normal conditions. To ensure that, it's important that the neutral and grounding wires not be connected outside the panel.

There's a lot more to be said, so much so that many whole books have been written on the subject, but I'll stop here.
 
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Old 07-17-02, 01:12 AM
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Tx , each time I read Wg's response , it starts to get a little more clear. I once asked an electrical contractor the same question about the neutral and ground bars going to the ground rod. He just said he didn't know! Heheh, I think I know now why he said that. I do have to wonder how many could actually explain it in detail.

John, I know why we have equipment grounds and about electricity taking the least path of resistance. I just didn't know the physics of it. I'm begining to understand that a little better now ( I think ). It is surprising that there are not more home electrocutions than there are. Interesting info on the ground rod and the neutral of the transformer. Kinda clears up another thing for me, and that is why the the rod does not zap someone if touched. I guess I should say if no short is present.

Appreciate the responses
 
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