Service Grounding

[mshields]

My wife asked me the other night if our house was protected from Lightning because of the fact that our service is connected to ground either by the water pipe or via a ground rod outside of our house.

First of all, I must tell you that I was shocked she had picked up even this much from me over the years. I hadn't thought she was paying attention to anything I said, let alone work related.

Be that as it may. I told her that this wasn't the case. And that if in the unlikely event (we live in New England) that our house was ever struck by lightning, we'd probably have a big chunck taken out of the top corner of our roof, not to mention the catastrophic surges in the electrical system.

We that as it may, it caused me to wonder why we bother to ground services at all (other than the fact that we must). Ground fault current goes back to the source, i.e. the transformer, does it not. This is what allows the CB to trip correct?

So what does the service ground, from a practical standpoint accomplish?

 

[jtester]

Numerous service still have extensive metal wter pipe connections that really do enhance fault current clearing, although they are becoming more rare each day.

I would contend that the neutral-ground bond is presently there pretty much to limit surges from outside. For example, if the utility primary fell on the neutral adjacent to your building, the bond would limit the neutral-ground potential difference on the building side of the bond. Without it, you'd have primary voltage on your neutral.

Jim T

 

[Dirk Diggler]

My wife asked me the other night if our house was protected from Lightning because of the fact that our service is connected to ground either by the water pipe or via a ground rod outside of our house.

First of all, I must tell you that I was shocked she had picked up even this much from me over the years. I hadn't thought she was paying attention to anything I said, let alone work related.

Be that as it may. I told her that this wasn't the case. And that if in the unlikely event (we live in New England) that our house was ever struck by lightning, we'd probably have a big chunck taken out of the top corner of our roof, not to mention the catastrophic surges in the electrical system.

We that as it may, it caused me to wonder why we bother to ground services at all (other than the fact that we must). Ground fault current goes back to the source, i.e. the transformer, does it not. This is what allows the CB to trip correct?

So what does the service ground, from a practical standpoint accomplish?

In my opinion the grounding electrode system serves no purpose. No one has ever convinced me otherwise. If there were to be a lightning strike, I suspect the lightning will disapate throught the entire electrical system. The old cliche of electricity follows the least path of resistance is not true. It will travel everywhere just some places less than others.

 

[bkludecke]

If you PM me I'll email you (or anyone else) a powerpoint that helps explain some of this stuff.

 

[celtic]

If you PM me I'll email you (or anyone else) a powerpoint that helps explain some of this stuff.

...and it's a dam fine PPS.

If I didn't before...THANKS
If I did....THANKS AGAIN

 

[ramsy]

...and it's a dam fine PPS.

How can Bob attach that *.PPS file to his post? Can someone help out here?

 

[Smart $]

How can Bob attach that *.PPS file to his post? Can someone help out here?

Perhaps by "zipping" it. That is, compress pps in a zip file then attach the zip file to a post. Note however the zip file must still meet the size requirement for attachments.

Otherwise, upload either the pps or zip file to a web server that permits the size and provide a link here.

 

[bphgravity]

So what does the service ground, from a practical standpoint accomplish?

If you read Section 250.4(A)(1), three issues are listed that indicate the purpose of system grounding. If you take each one individually, you will be hard pressed to find supporting documentation or evidence grounding accomplishes any of these functions.

In fact, there is plenty of evidence that grounding of the electrical system did not protect against or limit voltages imposed by lightning or high voltage cross over.