Well, I'm lucky, one of my good friends is a EE (Electrical Engineer). He taught me that, indeed, not all wires are created equal. Insulation widly varies and is probably the most important factor next to sizing it proper for the circuit. THere are 2 basic insulation types for automotive use. Crosslinked and non-crosslink. Non-crosslink is GPT rated, good from -40c to 80c. Cross link is rated -51c to 125c. But more importantly is the quality control of the manufacture of the wire as well. WHat you find at most auto stores, k-mart, sears, etc is "primary wire", perhaps not even GPT rated, but usally it is. (if the package doesn't state what the rating is, beware beware, very cheap, might melt in your hands!) But because this is the cheapest and most sought after for public resale , there are alot of unscrupolous manufactures of this wire, and it might not live up to the standard (in alot of cases, it doesn't). If you go for crosslinked wire, there's alot less of this (because it's more expensive), and usally only custom shops and OEM's are buying it so the quality control is there and it better live up to the standard. Cross link comes in SXL (thick insulation, better abrasion protection), TXL and GXL just thinner versions of crosslink, still living up to the temp standard, just a little thinner for easier packaging in connectors (like those 50+pin computer connectors). For marine use you get into tinned wires for corrosion protection, industrial uses, locomotive uses see still different insulations yet, but now your talking some major coin. I happen to have a 50' spool of 2 ga I scored (the loose coil on the right of the bottom most row in the pic) from a suite in a building where I used to work they were moving out and getting rid of thier "samples", it's rated -70c to 310c, for locmotive use. THis stuff is $38/foot if you went to buy it.
The SAE standards specifcally state that GPT wire shold not be used in the engine compartment of vehicles. Crosslink wire only here. The OEM's stick mostly with crosslink (SXL,GXL or TXL, the 'X' is for crosslink) wire throughout.
Terminal connections are another very important area of concern. Again, most auto store are selling very cheap viynl insulated terminals. These things suck, aren't sealed, are prone to a very poor connection, voltage loss, and longevity concerns. I
like solder ring heat shrink terminals, no crimping, insert wire, place infront of proper heat gun and it melts a pre-inserted solder ring and shirnks the heat tubiung around the whole thing, a perfectg sealed connection. Crimping can be good too, but more often than not, the person crimping doesn't know how to do it right and the connection ends up being bad. Now solder ring connections aren't without their problems as well, try doing that to a 50pin connector and you have 10lbs hanging off the connector body, not good. OEM's would avoid that, they would use just crimp style there.
I bought all my wire and terminals from
www.delcity.net. Other places sell all this stuff too, but they have the cheapest prices for most things (like the made in USA crosslink wire).
