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lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

1 edit
reply to 54067323

Re: Improper ground

said by 54067323:

said by lutful:

Lightning is not just DC.

And that is why impedance needs to be considered...

You see ...

Yes, I do indeed. I have been consistent in arguing for low impedance grounding for both code compliance and lightning safety.
»/nsearch?q=low···92875229

Once again, I mentioned lightning safety aspect only because it was not mentioned before and was relevant. Perhaps we should avoid discussing complex EE stuff in the home improvement forum from now on.

Hahausuck
Premium
join:2003-12-14
kudos:2
reply to 54067323

Is that bare CU touching the fence post below the clamp?



54067323

join:2012-09-25
Tuscaloosa, AL

said by Hahausuck:

Is that bare CU touching the fence post below the clamp?




Na that's a three part clamp designed for gate and fence post grounding, there is the u-bolt, a base clamp and a top clamp and the cable goes between the base and top clamps. The cool part is, it's rated for use with both copper strap and copper cable.

For what it is worth that cable goes down then curves outward where it’s welded to a ring the encircles the entire site (350’ by 350’) which is in turn is welded to a ground grid with a four by four foot conductor spacing that is underneath the site.

That’s almost 61,000 feet of conductor in the earth.

Needless to say, the owner of the site is very serious about grounding.


54067323

join:2012-09-25
Tuscaloosa, AL

2 edits
reply to lutful

said by lutful:

Perhaps we should avoid discussing complex EE stuff in the home improvement forum from now on.

Wait a second. Are you saying the members of this forum, both the regulars and the visitors are not intelligent enough to understand or participate in a discussion involving things such as resistance and impedance or grounding and bonding?

Lutful, that is just not so, there are members of this forum who on a day-to-day basis design, install and maintain electrical equipment, a process that requires them to have an intimate knowledge of those four items listed above and many more.

It seems you have something against those, who you perceive are not EE’s.

said by lutful:

Very few electricians seem to trust electrical engineers messing with their "field of expertise" ... I had some nasty arguments with forum electricians who blamed mysterious ground loops and bad ground"ed" wiring for almost any equipment problem while suggesting horrible ground"ing" solutions.

Why is that?

Hahausuck
Premium
join:2003-12-14
kudos:2
reply to 54067323

Yeah but where it comes up out of the conduit it looks like it is.....



LazMan
Premium
join:2003-03-26
canada
reply to lutful

said by lutful:

I just wanted to clarify an important safety aspect which was not mentioned by others.

Technically all metallic pipes/objects near the walls are supposed to be bonded in such a way that their voltages will be quite similar and also will quickly rise and fall to the same voltage as the real ground.

Otherwise, there could be dangerous voltage differences between these objects during a lightning storm which can start a fire or electrocute someone.

Above photo (by Dehn) shows such "equipotential" bonding of metal pipes.

Look up 3 posts... :S

As for the desire to keep "complex" EE-only propeller head stuff out of home improvement forums... Well, we're two steps away from putting a toliet paper roll around the ground strap, here, as far as I can tell...

BTW - 15 years in DC power, grounding, bonding, and telcom electrical... This stuff's ALL way over my head! :S

lutful
... of ideas
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join:2005-06-16
Ottawa, ON
kudos:1
reply to 54067323

said by 54067323:

For what it is worth that cable goes down then curves outward ... welded to a ring the encircles the entire site ... almost 61,000 feet of conductor in the earth.

Needless to say, the owner of the site is very serious about grounding.

That may be true, but he wasted a lot of dough.

That "cable" may be satisfying code for human safety in case the fence became energized, but it will NOT be carrying much current during a lightning strike.

Any competent EE student can verify this fact using a Rogowski coil on that silly cable while exposing the fence to lightning test waveform: the lowest impedance path to ground will be straight down that fat fence post.

robbin
Premium,MVM
join:2000-09-21
Leander, TX
kudos:1

Are you saying that the fence should not be bonded to the site grounding system?



mackey
Premium
join:2007-08-20
kudos:8

said by robbin:

Are you saying that the fence should not be bonded to the site grounding system?

No, it was a sarcastic remark (notice the smiley) implying the 61k feet of conductor was put in the ground for the sole purpose of grounding that fence to protect it/something near it in case of a lightning strike.

/M


54067323

join:2012-09-25
Tuscaloosa, AL

3 edits

1 recommendation

reply to lutful

said by lutful:

That "cable" may be satisfying code for human safety in case the fence became energized, but it will NOT be carrying much current during a lightning strike.

All I can say is, you have seriously underestimated the amount of energy a lightning strike can deliver.




BTW here in the US we not only bond gate and corner posts to the ring/grid, we bond the fence posts to it as as well.

Any competent EE student can verify this fact using a Rogowski coil on that silly cable while exposing the fence to lightning test waveform.

In the furture, I would suggest you dig through some of the research done by the EPRI and the NIST before coming to such a silly conclusion.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

Click for full size
said by 54067323:

All I can say is, you have seriously underestimated the amount of energy a lightning strike can deliver.

No. I only emphasized that only a small fraction of that energy will flow down the cable because the post will provide a much lower impedance path.

I already posted a search report of old posts which contain "low impedance" ... read some of those. Do a search on "rocket triggered lightning" ... one of my hobbies is measuring lightning strikes for science.

said by 54067323:

BTW here in the US we not only bond gate and corner posts to the ring/grid, we bond the fence posts to it as as well.

I quickly searched and found a typical US requirement for fence grounding. Read the first para carefully.

Experts even recommend electrically isolating fence sections and grounding them separately (for electrical safety). Otherwise, dangerous voltages are presented to cows (and humans) during a strike event anywhere along a long fence. You don't want that.

Check NFPA 780 or lightningsafety.org guidance for metal fences if you really want to educate yourself. And please do NOT bring "here in the US" or "there in the third-world" prejudice into future technical discussions.


John Galt
Forward, March
Premium
join:2004-09-30
Happy Camp
kudos:5

The requirements for electrical substations and switch yards are very specific as there are other issues that are being mitigated beyond lightning.


lutful
... of ideas
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join:2005-06-16
Ottawa, ON
kudos:1

said by John Galt:

The requirements for electrical substations and switch yards are very specific as there are other issues that are being mitigated beyond lightning.

If those fences surrounded any such facility, "site owner" or "electrician" will be either in jail or dead.

There is really no need to patronize an EE who has helped such facilities test grounding systems "in situ" with lightning waveforms and offered to do the same for any facility managed by nunya See Profile or 54067323 See Profile or AMDfreak See Profile a few years ago during more relevant discussions.

You can look up those threads but we should not start utility or telecom site grounding arguments in this clearly residential topic.


Jack_in_VA
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join:2007-11-26
North, VA
kudos:1
Reviews:
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said by lutful:

You can look up those threads but we should not start utility or telecom site grounding arguments in this clearly residential topic.

I agree


54067323

join:2012-09-25
Tuscaloosa, AL

2 edits

1 recommendation

reply to lutful

said by lutful:

If those fences surrounded any such facility, "site owner" or "electrician" will be either in jail or dead.

Really! In jail or dead for following recommended engineering practices.

Don't you think that is a little over the top?

Anyhow, this document by the US Department of Energy backs up the practice, I have already posted.







Note the enlargement of the upper left hand diagram, and note the ties to the main grid.

By the way, we in the US use the same design for CCI.

Hahausuck
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join:2003-12-14
kudos:2

1 recommendation

reply to John Galt

I actually have seen several substations here lately that all have extensive bonding of the fence posts as well as the fabric. I was impressed.


nonymous
Premium
join:2003-09-08
Glendale, AZ

2 recommendations

reply to Jack_in_VA

said by Jack_in_VA:

said by lutful:

You can look up those threads but we should not start utility or telecom site grounding arguments in this clearly residential topic.

I agree

If I can not mess up a homeowner job myself I just hire someone out front of homedepot. Costs less than a trade professional and unlike an engineer may actually get the job done without endless nitpicking. ;)
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lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to 54067323

Re: Improper ground

said by 54067323:

said by lutful:

If those fences surrounded any such facility, "site owner" or "electrician" will be either in jail or dead.

Really! In jail or dead for following recommended engineering practices.

No. I implied they would be dead or in jail because of some fatal event. Your original fence photo with the clamped conductor was a pathetic example of grounding for either electrical or lightning safety.

The next photo with exothermic bonded conductors is better but still far from the "recommended engineering practices" for utility substations. But please take that discussion to another forum.


grobinette
Southeast of disorder
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Springfield, VA
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1 recommendation

reply to IowaCowboy

Man, did you guys drift off into never never land. The original question was about IowaCowboy See Profile's grandma's grounding. Is it done correctly or not?



54067323

join:2012-09-25
Tuscaloosa, AL

4 edits
reply to lutful

said by lutful:

Your original fence photo with the clamped conductor was a pathetic example of grounding for either electrical or lightning safety.

Well that is how the U.S. government requires the work to be done, if you have a problem with that take it up with Uncle Sam, not me.

Again I refer you to a document from the U.S. Department of Energy...







FWIW that clamp is a Burndy GAR series U.L. listed mechanical connector designed just for that purpose.






54067323

join:2012-09-25
Tuscaloosa, AL
reply to grobinette

said by grobinette:

Man, did you guys drift off into never never land. The original question was about IowaCowboy See Profile's grandma's grounding. Is it done correctly or not?

Based upon the photographs and what he has posted it appears to have been done properly and safely.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to 54067323

said by 54067323:

said by lutful:

Your original fence photo with the clamped conductor was a pathetic example of grounding for either electrical or lightning safety.

Well that is how the U.S. government requires the work to be done, if you have a problem with that take it up with Uncle Sam, not me.

No. If you are truly unable to see it's flaws, there is nothing more to say. Get Uncle Sam to review your handiwork.

I am NOT proposing less protection than US Govt. guidelines as you keep implying. I am proposing MORE protection by lowering impedance of the grounding conductors. I have no issue with above suggestions (for example) but you will probably find some way to dismiss it. Go ahead.


54067323

join:2012-09-25
Tuscaloosa, AL

said by lutful:

I have no issue with above suggestions (for example) but you will probably find some way to dismiss it. Go ahead.

I don't but apparently you do...

said by lutful:

The next photo with exothermic bonded conductors is better but still far from the "recommended engineering practices" for utility substations


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1

I put in those highlights in green to show how the conductors should run straight down into the ground and then bend gradually below grade to bond with the ground grid. That makes a huge difference in impedance values measured under simulated lightning waveform.



54067323

join:2012-09-25
Tuscaloosa, AL

2 edits

said by lutful:

I put in those highlights in green to show how the conductors should run straight down into the ground and then bend gradually below grade to bond with the ground grid. That makes a huge difference in impedance values measured under simulated lightning waveform.

Like sweeps?

said by lutful:

Longer sweeping bond wires may measure higher "impedance" between 100Hz and 10Khz than a shorter bond wire even with a relatively sharp 90 degree bend.

So now you are advocating using sweeps?

That’s IMO kinda circular logic.
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