Dumb question: tractor + electric fence

[joshuabardwell]

The truth is, your tractor nor you will get shocked since you are insulated by the rubber tires.

The rubber tires are some help, sure, but they're not impervious. Remember that an electric fence is intentionally designed to drive current through things. They typically operate at between 3000-7000 volts. The real reason, IMO, why you won't get shocked if you're actually on the tractor, is that there are much better paths to ground than your body. So if the mower deck touches the lower wire, for example, the electricity will travel through the deck, through the lower part of the frame, and out the tires. You're not significantly in that path, so you don't get shocked. If, on the other hand, I stop the mower touching the fence and get off, then touch a metal part of the mower, I will get shocked, because I am now the least-resistance path to ground.

Even if you did, it is not enough amperage to make a spark

This has not been my experience. I have electric net fencing, and if two strands are close to each other, I will definitely see a small spark and hear some popping. I have also seen sparks when I am clipping an alligator clip onto the main fence wire. Do I think there's any risk of blowing up a tractor? Not hardly. But electric fences definitely can have enough charge to spark.

[Gary Fowler]

Fence chargers definitely dont have a spark as hot as spark plug wire from someone who has touched both. Yes it will spark but is the spark hot enough to ignite diesel, I dont think so.
I have witnessed a rubber tired crane hit a main overhead electric trunkline that was 48Kv line and the operator sat in the seat till the power company turned off the power. The current went thru the boom and out the front outrigger which was not more than 3 feet from the operator with the only effect a big pile of glass under the outrigger pad which was setting on sand and it melted about a 4 foot ball of glass under the pad. Had he tried to dismount the rig, he most certainly would have died. A few months later a transformer blew up coming off that same line and it was arcing 4-6 foot arcs all over that pole for several minutes till power was shut off.
But that is ultra high voltage AC current and the fence is milliamp DC which is far less dangerous than AC. I mow under my electric fence all the time with gasoline mower and dont worry about anything blowing up or damaging the mower either.
There are much more dangerous things on a farm to worry about than an electric fence.