I'm trying to list possible characteristics of an electrical wire and would appreciate if you can pitch in with things to consider. This is in general for all types of wires.
Resistance
Maximum Current / Voltage
Temperature
cheers,
pracas
This sounds like a homework assignment. 
Not much else for wire other than it's mechanical size, diameter, solid / stranded, tinned or enamel covered or insulation. Metal it is made from, its purity and melting point.
Kind of Homework trying to build a wire tester that can test wires.
I think wire's capacitance can be important if you're using it to send high speed signals.
-Mike
A wire does not have capacitance.
A multi stranded cable might but a wire doesn't. It will have inductance though but that is just the result of the mechanical length of a current carrying conductor. It is not a function of the wire itself.
I guess you could test for that stuff but a lot of the testing could easily be destructive. I don't know how you'd test max temperature without ruining the insulation. Max current is sort of a weird one as you can force a lot of current through a wire (up to the theoretical max of volts / resistance) but you really shouldn't. It's more a question of how many amps you can do before the insulation around the wire catches fire and burns your place down. And you can push a lot more amps through a wire momentarily than you should continuously. A wire with 0.05 ohms resistance could pass 2000A at 100V but you had best not try that for more than a tiny fraction of a second.
But... in the real world, why not just use a wire capacity chart? If you know you've got 10 gauge wire then you can easily look up the max safe amperage. If you can read the side of the wire you'll find out if it's THHN or what and then you know the temperature rating and voltage rating. Knowing the gauge (and length) gives you a really good idea of it's resistance too.
AdderD,
Thats the kind of testing i'm trying to build a tester for. I know things will burn but need to know the set of conditions they will burn for and things like that(the extreme temperature might be skipped - not sure how to generate so much temperature as well as test the wire ). Reading the wire will do but i think most ratings are based on test conditions so its like to build a tester that can test the wire for various kinds of specific working conditions and define different types of tolerances.
Cheers,
Pracas
A wire does not have capacitance.
Sure it does. Wires have distributed resistance, inductance and capacitance. Study the early days of trans Atlantic cables for some interesting history.
I'm trying to list possible characteristics of an electrical wire and would appreciate if you can pitch in with things to consider. This is in general for all types of wires.
Resistance
Maximum Current / Voltage
Temperature
Resistance is a function of the metal. Current is related to this and to the temperature.
Maximum Voltage and Temperature are functions of the insulation.
I think a distinction between a wire and a cable is needed to decide on capacitance.
Capacitance is the ability to store charge. Even a single wire has a capacitance, probably large enough to come into play for any circuit where a single wire is useful (antenna? I hate Antenna physics!)
For instance, the capacitance of an isolated conductive sphere is about (1.1e-10 * R) (Farads)
(4pie0*R)
(This usually comes up in electrostatics (very high voltages with tiny currents.) The sizes of the top of your Van de Graff generator does matter.)
http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/capsph.html#c2
I think a distinction between a wire and a cable is needed to decide on capacitance.
A cable is a wire. The designers of early telegraph cables assumed they could treat it as a DC device - they were very wrong.
Resistance is a function of the metal. Current is related to this and to the temperature.
Maximum Voltage and Temperature are functions of the insulation.
Nice way to categorize and look deeper. This will help. Only i don't get how voltage is a function of insulation. :-[
Cheers,
Prakash
i don't get how voltage is a function of insulation.
There are the physics properties of the wire itself, and then there are the practical realities of trying to use that wire in a circuit. If your (insulated) wire is right next to another wire in a cable, there is a chance that the voltage difference will be large enough to "break down" the insulation and arc over, causing catastrophic failure and perhaps fire, electrocution, etc. Most "typical" wire is rated at 600V, which means that the voltage properties of the insulation are pretty irrelevant in typical arduino circuits (or even in AC-power tube circuits). If you start talking about tesla coils, microwave ovens, or particle accelerators, or even CRT circuits, you have to start looking around for special wire with better insulation. (Likewise, insulation can have an effect on current rating. Enough current will cause the wire to heat up, and while that might be permissible to the metal wire itself, it can cause the insulation to melt...
I was going to say that you should check for insulation color too, because I frequently want to know what signals are on what color of wire. But I decided not to...
Something I cant get my head round. If a wire has capacitance where are the two balancing charges, one is on the wire, where is the other one? (assuming there is no insulation).
The rest of the universe!
You push some electrons down a wire, they have a -ve charge. The charge attract positive charges from everything (or repels other negative charges) - the effect gets smaller and smaller as things get further away, but that is the effect.
The rest of the universe!
Think big 
Take a look at this site. I think it will give you a lot to work with:
The "balancing charge" is presumably on whatever device applies charge to your isolated conductor in the first place. I mean, assume the two-conductor cable where we have no problem understanding the capacitance. Apply +/- 1000V briefly on the two conductors to "charge" this cap, and one ends up with a surplus of electrons and one with a deficit.
Now separate the conductors. To infinity (and beyond!) Clearly the wire with the extra electrons still has them (they had no where to go), so even the singe wire does have a capacitance.
Something I cant get my head round. If a wire has capacitance where are the two balancing charges, one is on the wire, where is the other one?
The nearest objects, such as the ground or anything else. Unless the wire is out in space there's always something. That's also why they hang very high voltage wires way up above the ground - apart from safety reasons, the losses would be great.