Ahhh, the Theory(s) of Conduction... so many ways to explain it, so many ways to view it.
Off the top, in reality almost everything is Conductive. Sounds wierd? just wait to hear this next one!
The one and only "True Insulator" is... Water!
Alright, not all the facts are here, but I just wanted the "Shock Value" (no pun intended).
Pure Water - being that the Mole is comprised of nothing more than Hydrogen Oxide (2 Hydrogens bonded to a single Oxygen) is a non-conductive Molecule. There's no free Electrons in the outer valence which may be "knocked off".
Water does not become conductive, it only "holds" minerals which are conductive. This is done via the Solvent (Scraping) processes of Water (it's known as "The Universal Solvent").
Once a certain mass of Water scrapes and holds conductive materials, then the complete mass is a conductive material.
OK, so much for the Water thingee...
Conductive properties are - in our field of applications - what Materials will have a high conduction value (High MHOs, low OHMs), and we will use these Materials for our Power Conductors.
Our Insulating Materials will offer a very low conductive characteristic. We coat our conductors with those insulating materials to keep the smoke from leaving the conductors.
Even though we could hold a live conductor, which has THHN insulation on it, and not get shocked on a <1000 volt system, here are two things to consider:
[*]The max. voltage for that insulation is 600 volts - what happens if we connect it to a system with potential of 6000 volts... will we still be able to hold it without a shock?
[*]With a non-contact circuit being coupled via a Reactive coupling effect, would this be possible if the insulation was 100% effective to stop the flow?
Now we begin to see where the fine line of "Conductive vs Insulator" is.
Highly conductive materials have an abundance (sp???) of free Electrons in their outer "Shell(s)" of orbiting Electrons, and the energy required to move a free Electron from one Atom to another is somewhat low.
Another high conductance property is having lots more conductive structures than non-conductive impurities, mixed together in a given Mole of material.
Semi-Conductors are named this due to their ability to conduct highly in "One Direction", and conduct very poorly in "The Other Direction".
Conductance is a very interresting property of materials (or absence of materials - such as Vacuums), and characteristics which effect things include Potential Difference (Voltage), level of currents available, frequency, and yadda-yadda-yadda
Let me know if this makes sense, no sense, or your head spin!
edited to correct a run-on sentence... hope I do not find others!
[This message has been edited by Scott35 (edited 01-21-2004).]