TRactors and lightning

[MarkV]

KCB, when you say "avoid ground loops", can you explain what you mean? (to someone who knows how to put the plug in the wall socket)/w3tcompact/icons/smile.gif

 

[PBMAX]

I know a poor fella whos home gets hit by lightening several times a year...Some times it just startles them some times it fries things...He lives up fairly high and has only 2ft of top soil...He had to desing a fairly solid grounding system to protect his home...the hill he lives on is some type of rock that makes it hard to get a good ground...He told me he even gets ball lightening on occasion...Some one mentioned plumbing and how newer home are better grounded to day...But has KCB and WEN and probable a couple of others have pionted out lightening is both flakey and completly unpridictible...I did electrical work for 4.5 yrs and have seen lightening do some realy ammazing stuff...And damage...My boss at the time has an aunt that lightening hit here home...1st it hit a rod iron fence then jumped to a tire rim on the front end then out the back rim on the opposite side...then into an outside outlet back to the panel wich it promplty blew off the wall along with frying qiut abit of wiring along the way...Over all about 2k worth of damage.Plus the headaches that go with all the repair....If he hadn't had picture to prove it know one would believe it...

Lil' Paul

Laziness is the Father of invention.../w3tcompact/icons/laugh.gif

 

[KCB]

Since I mentioned the need for a single grounding point for lightning protection, I've found varying opinions on whether it's necessary. (again opening my mouth too soon). Ground loops can be formed in multiple grounding point circuits because each point will have its own resistance or inductance to ground. Grounding loops then result when ground seeking currents flow through the connections (loops) between the multiple grounding points , that are normally at the same ground potential. This could interfere with effecient grounding of a surge. If I'm wrong.... again, someone please correct me. I remember from working on old Dynaco tube amps, that multiple grounds could cause some annoying feed back problems and circuit oscillations.

 

[W5FL]

KCB,

The issue is complex. Single point grounding is to prevent ground loops and is one way to prevent hum at audio frequencies as you suggest. Lightning protection is a simple matter of trying to keep all points in close proximity at the same potential and by definition requires many point grounding, but single point entry is safest for electronic protection (but not possible in most real world situations). For those that really want to understand it, the reference to Polyphaser's book is the best there is.

Unfortunately, the only comment that applies to tractors is to head for the barn at the first sign of a thunderstorm. You are not safe on the tractor, under the tractor, or beside the tractor. /w3tcompact/icons/smile.gif

 

[TomG]

Yes, I think that Wen's gentle suggestion to stick with tractor related discussion makes pretty good sense. I'm more guilty than most of digressing from tractor subjects.

So, 'head for the barn' is good advice. As far as I know, if you get caught in the open, squat down on the balls of your feet with your head between your knees. A pointed object, like my head, sticking up makes a good conductor. My other end isn't so pointed. You know that you have to do something quick if you feel you hair start to stand up.

I ran a sound and lighting company for 10 years as a sideline business. I had a sizable PA for live music. I do know quite a bit about ground loops in audio equipment. If somebody really is interested, I could describe the basic grounding concepts, probably through private messages. It's hard to make the music business tractor related.