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Lihtning protection problem
By hvirtane, Section Homebrewed Electricity Posted on Tue Oct 05, 2004 at 05:25:11 PM MST
We got a problem with different metals

The grounding wires for lightning
protection is with copper wirings
going near the guy wires in the ground.
Now we realized that there is
voltage of 0,8 V between guy wires
and the grounding copper wires.
That means of course that there
will be slow corrosion metal
being moved off from the guy wires.
What kind of method would you
recommend to stop the electrolytic
corrosion?
- Hannu

Lihtning protection problem | 10 comments (10 topical)

Re: Lihtning protection problem (3.00 / 0) (#1)
by Harry Luubovv on Tue Oct 05, 2004 at 05:49:01 PM MST

I am not very sure about the real problem as I do not know how your lightning protector works iside, there should not be any hot potential on that copper wire. I take it that the protector requires you to connect one of its wires onto the hot wire of the gennie, and there is a small leakage internally in the protector. In this case, the protector itself can be a problem, it presents leakage however small. But one can connect a small gauage wire between the copper wire from the protector and the guy wire. Putting a 50 milliamp or thereabout range fuse in between the wires. If the fuse blows, return the protector for a refund. If it does not blow, it means that this is safe to use as is, but you do waste a small part of the electricity from the gennie. But many times, leakages like these happen because of circuitry designs, not a construction defect.

Happy days,
Harry.

Re: Lihtning protection problem (3.00 / 0) (#3)
by TomW on Tue Oct 05, 2004 at 06:02:10 PM MST

Harry;

I think he is concerned with galvanic corrosion from dissimilar metals in contact with one another.

beep beep vrooom.

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

[ Parent ]

Re: Lihtning protection problem (3.00 / 0) (#6)
by Harry Luubovv on Tue Oct 05, 2004 at 08:17:14 PM MST

Oops, sorry TomW.

I think you are right.

Hope your "Low Key Security" is doing great.

Have a great day man !
Harry.

[ Parent ]

Re: Lihtning protection problem (3.00 / 0) (#2)
by TomW on Tue Oct 05, 2004 at 05:55:05 PM MST

hannu;

Just an off the wall idea:

Use zip ties in a figure 8 to hang the ground so it does not touch the guy wires. I do this to hang power feed wires from a steel cable so it doesn't wear the insulation off from motion. It is cheap and seems reliable so far over 3 years. I pull the zip ties tight and it doesn't move or let them touch.

Cheers.

TomW

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

Re: Lihtning protection problem (3.00 / 0) (#4)
by richhagen on Tue Oct 05, 2004 at 06:08:42 PM MST

I'm assuming your talking about electrolysis between the grounding wire and the guy wires where they are anchored by electrolysis through the damp soil. If that is the case and they are near each other, could you use an appropriate clamps or connectors and connect the two by wire just above the ground? You could bury the connecting cable in between so that it would be out of the way. The idea being that this way all of the cabling/wire would be at the same potential, preventing the electrolysis in the wet soil. I don't think that this would effect the lightning protection as the bulk of the current would find the path of least resistance to the ground through the copper conductor. Rich Hagen
'A Joule saved is a Joule made'

Re: Lihtning protection problem (3.00 / 0) (#5)
by tecker on Tue Oct 05, 2004 at 07:39:34 PM MST

Wood ashes to get the ph up should do .

Re: Lihtning protection problem (3.00 / 0) (#7)
by nack on Tue Oct 05, 2004 at 08:31:14 PM MST

You might find this site to be of interest: http://www.corrosion-doctors.org/CP/sacr-calcul.htm

It talks of cathodic protection strategies, and has some examples for designing sacrificial anode systems to protect pipelines and transmission tower feet. Sounds like you will be investing in magnesium anodes, or impressing positive current on the copper to bring it above the iron's potential.

Re: Lihtning protection problem (3.00 / 0) (#8)
by Roamer195 on Wed Oct 06, 2004 at 05:57:28 AM MST

Get the correct alloy solder and "tin" the aluminum AND the copper in the contact area. Then there won't be any dissimilar metals contacting eachother.

Re: Lihtning protection problem (3.00 / 0) (#9)
by Ungrounded Lightning Rod on Wed Oct 06, 2004 at 06:49:59 AM MST

Why are you making a connection between the guy wires and the electric wiring at all? The guy wire anchors (if they're into soil, rather than, say, rebar cemented into a rock or in a cement shoe) and the tower base itself should provide the lightning current path for the tower, while the copper ground rod provides it for the wiring. Connecting them promotes galvanic corrosion but leaving them floating avoids this issue.

Note that a nearby lightning strike can produce a significant ground bounce between grounds in different locations. If your protective ground rod for the wiring is not within the circle of the guy wires a hit on the tower will produce major voltages between the wiring and the tower. If you connect them (or connect your wiring to a local wiring ground) you get lightning current in your wiring, while if you don't you probably get an arc damaging your insulation plus SOME lightning current in your wiring.

I'd compromise by putting a half-turn bend on a 6" radius (or a couple turns ditto spaced out an inch or so per turn) in the wire where it gets to the base of the tower, with a three-phase surge arrestor on the tower side of the coil hooked to the tower (or the local electrical protective ground rod, which would also hook to the case of the alternator through a "drain" wire if there isn't a good path from it to the tower - but NOT if there IS a good frame-tower path since that would produce galvanic trouble and electroerosion of the yaw bearing), and a similar loop where the wiring hits the house - maybe with another arrestor on the house side to the house ground if I wanted extra protection. (Do you have a separate battery shack? Where's it located?) I'd also run a heavy ground "drain" wire between the house and tower protection rods in the same run as the feed, to take any ground surge current so it isn't tempted to jump to the hot wires. Treat it like a utility feed.

Lightning starts and stops abruptly, which maps into a VERY high frequency. So even a little inductance when there's an alternative path cuts the currents drastically. This is the "other function" of the "drip loop" where the wiring hits the house. (Did you ever notice that utility service wires make a loop where they hit the service entrance, just before going into the conduit? That's why. It's not just slack for convenient splicing.)

Re: Lihtning protection problem (3.00 / 0) (#10)
by hvirtane on Fri Oct 08, 2004 at 11:46:41 AM MST

Thank you all a lot for
many good thoughts.

With my friend
(the wind machine is not mine,
and my friend isn't registered here)
we are now studying what to do
for it.

I will write more, when got
more knowledge from my friend
what he will do.

- Hannu

Lihtning protection problem | 10 comments (10 topical)

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