Ground rod in every light pole?

mtnelect

HVAC & Electrical Contractor
Location
Southern California
Occupation
Contractor, C10 & C20 - Semi Retired
I see a lot of contractors on this forum, who have a dispute with a customer or general. "If they will not pay me" I will take them to court. Careful about what you wish for.
 

cpratt

New User
Location
Tulsa, OK
Occupation
Electrical Professional Engineer
One of the topics I teach in my grounding courses is that, contrary to popular opinion, a bend in a conductor will not increase the end to end total impedance. A bend, even a sharp bend, does not increase the impedance of a conductor for a given length of wire. A bend can reduce the impedance of a conductor to any time varying waveform such as AC currents and lightning impulses. The reason for the reduction in impedance is based on inductance equations. The inductance is the predominant driver of impedance for time varying currents, which in the case of lightning currents are made up of high frequency currents. For a given length of wire the total impedance, inductance plus resistance end to end, will become lower as you place a bend in a conductor with the lowest impedance being the case where the conductor doubles back on itself. Of course the lowest impedance of conductor between two points would be a straight line in lieu of using excessive wire. Using a longer conductor than necessary with bends in it may have a slightly higher inductance than the shortest conductor between two points but the increase in impedance is merely due to the use of a longer than necessary conductor to interconnect two points. If you want the lowest impedance, use the shortest conductor and in the case of lightning currents forget about using larger conductors than necessary. For high frequencies larger conductors most likely will have a higher total impedance than you think due to skin effect on the AC resistance.
An example: A 5 ft length of wire of any size will have an inductance of about 1.85 micro-Hys/ft. The same 5ft. wire with a sharp 90-deg bend in it will be 1.64 micro-Hys/ft. The same wire doubled back on itself forming a 45deg angle will be about 1.37 micro-Hys/ft. Lower inductance: lower impedance.
 

Sberry

Senior Member
Location
Brethren, MI
Occupation
farmer electrician
I looked at an insurance adjustment. Great for the owner, the strike "hit the well" They dont have a clue what they were looking at. Well, its hits the TV and most everything on one circuit thru this mobil,,,, By following all this could see just what happened. There was a circuit to a tin shed hooked on thru the outdoor of the trailer. Grounded circuit mounted on a tin shed on dry wood poles. If a guy sketched it could se,,, it struck the shed, no rod, followed the eg thru the place, no ground, to the service where the electrodes were rotted off,,, no earth connect there so it followed the eg to the well motor downhole was in a steel casing. No Ground wire from service to casing.
Absolute poster case for no electrode in the system anywhere.
 

Sberry

Senior Member
Location
Brethren, MI
Occupation
farmer electrician
I want to thank Don 19 here,,, I study under him and Keis on ETF for quite a while, amazing they didnt toss me when I didn't know one letter from another but it has paid well. Some of this really became clear, big moments when I was installing one of my own wells in 6 inch steel,,, that and the analogy of the parking lot rods, I was in quite a discussion about that and it took a bit before it became "instinctual" so to speak about possible ground array.
Want a real cluster we can get into bonding steel structures, multiple benches, multiple welders. That is one really brings out the "amateur" opinions for lack of better wording and points out that a lot of people including some long time masters do not have "complete" grasp on some of this or simply dont work with it to become second nature.
When lightening shows up on another forum a guy named westom stops in, gets accused of being a carpet bagger but he leaves the outlet questions for others but I believe is engineer in this field dealing with suppressors. Usually gets picked on by someone doesnt get it and I had some exposure thru it on etf so I recognize it.
Like the man says, suppressor doesnt work without the rod so to speak.
 

Sberry

Senior Member
Location
Brethren, MI
Occupation
farmer electrician
I remember asking Keis abouyt the well,,, do I need suplemental rods,,, he said... NO, the casing is the super electrode and want single point, said to clamp it and I said, I can do better, I can weld a lug to it. After I redo services, read the code about telephones which the co installers have not I eliminate all the strikes that were regular every storm. I would have to say it works.
 

Sberry

Senior Member
Location
Brethren, MI
Occupation
farmer electrician
If you want the lowest impedance, use the shortest conductor and in the case of lightning currents forget about using larger conductors than necessary.
I wondered if upsize for a longer run when it had to was worth it. I remember someone saying,,, dont bother.
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
I think that lightning down conductors required to be larger for taller structures.

However I don't think this is because of impedance or voltage drop, but because of the probability of higher current strikes.

Jon
 

Sberry

Senior Member
Location
Brethren, MI
Occupation
farmer electrician
The incident led to my quest5ion a wayyys back in another time and place was related to phone service. Phone conductors are also so small the listed wire, 14 I think is so much larger and then some prolly doesnt matter.
You got to love some of those guys,,, I asked,,, why dont you properly ground this? The answer,,, I dont understand why. I felt like slapping this dink, seems if he dont understand maybe he should follow the instructions. Stikes simply passing thru the protection wasnt grounded to internal modem of computers that were. It took the suppressor strips out,,, they were grounded.
Took me a couple 3 incidents to figure this out and a breeze thru art 880.
 
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