SWEET!!! I just scored a Pile of used CAT5 Cables for free on the side of the Road the other day. I already have plenty, so now I'll have something to do with all these extras.
I suggest a little, simple test when using a length wire of an unknown provenance. Can be done with twisted pair or used two conductor wire. Strip both conductors on one end so you can connect up an ohm meter. Separate the two conductors on the other end. If the ohm meter/continuity tester indicates a short (ie. 0 ohms when it should be infinite) means some of the insulator melted between the two conductors and that length should be discarded. Especially if one is interested in using it for homemade ematches. Now with the options out there for commercial ematches, it's less likely anyone is going to be making them from scratch.
Obviously, if one is using brand new wire and not wire that someone has already blasted 80 amps through an 18ga. nichrome heating element, this test is superfluous. If a sufficient amount of heat is generated along the length of the igniter wire, some melting and contact might occur between the conductors after use that is not easily seen. It's a simple enough to test with a cheap ohm meter that the insulation is intact between the two conductors of leadwire.
BEGINNER IGNITER TIP:
If one dips a batch of igniters and finds out that they just go "POP", blow off some of the pyrogen and don't flare, don't despair. Let 'em "age" a little longer (a few months) or better yet, simply take your fingers and gently bend and crack the pyrogen transversely along the length 3 or 4 times. If you do it carefully the pyrogen will stay on the end. Do that and they'll work.
What happens is when one blasts the igniter with a zillion amps, one spot on the wire may create a little more heat and the pyrogen overlying this spot generates the products of combustion that finishes off the bridgewire before the rest of the wire has heated up enough. The gas from the products of combustion "pops" and blows that little area off the igniter and breaks the wire. Hence one sees an igniter with one small piece of the pyrogen blown off and a broken bridgewire.
Now, when I had a batch of these "poppers" I was trying to figure out what was going on. I was messing with them and connected them up to a partially spent 12V battery to test further. I found out that the nichrome bridgewires gradually heated up and the pyrogen would catch and burn. It occurred to me that something was happening in a segmental fashion when a lot 'o amps passed through that made the igniters "pop". I guessed by cracking the igniter transversely along the length of the pyrogen head that it might allow some of the gas of combustion to diffuse out and allow enough time for with pyrogen to uniformly catch.
Anyhow, if one dips a batch of "poppers" try cracking the pyrogen heads just before putting the igniter in the motor. You might salvage the bunch. Kurt