Cables and Wires

[wakanga]

guys this is my first thread in this forum, but i'm already lurking here for about a year now..and now i'm already decided to build my first e-fire gear..i just want to ask some questions regarding cables and wires...and before i forgot i want you to know that i would fire using nichrome wrapped fuses for the meantime..im into computers so i have here cables that is used most for computer networks which is cat5e 24awg..will this thing work if i use it to connect my panel and slat at about 30meters to 50meters? can they carry voltages from 12 to 24 and what is their amperage tolerance? how much amperes can they carry before they get burned or fried...thanks..i will have questions later as i go on with my project thanks guys for the inspiration...

[JoeRatman]

I really think 24 gage is too thin for your purposes. It has too much resistance.

I remember seeing some CAT cable that was 22 gage. I would go with that. But to burn wire wrapped fuses at 30-50m, I think you will have to use 24 volts.
At 50m I am thinking you may need higher voltage. These are just off-cuff estimates.

[PyroZ]

Expanding on what Joe said, a lot will have to do with the gauge of nichrome that you use. Though it is a bit of a pain to work with due to its fineness (like fine hair), I have been using 40 AWG nichrome. With 4 to 5 turns around just about any fuse, I am able to reliably and quickly ignite the fuse using 12 volts through 100 feet of 24 AWG telephone wire. Smaller gauge (thicker) nichrome demands more current and will start to fall victim to the resistance of your shooting wire.

[johnny_boomboom]

24ga will work fine to about 40mtrs with 40ga nichrome... it is really pushing it with 35ga. 22 Ga should work for that... I wouldn't really using anything less than 22ga to connect the slats back to the control box... from the slat to the nichrome 24ga is more than fine...

[wakanga]

thanks for the response guys...so basically the cables your using for your control box to run to your slats is 22AWG telephone wire for lesser resistance if ever i use a 31 to 35ga nichrome...

please do clarify this for me guys..for just how long does the nichrome becomes hot before breaking? what does the ideal time for it to become hot before breaking? thanks

[JoeRatman]

I like my nichrome wires to heat and break in less that one second. At that point, it seems almost instantenous. By the time you push the button all the way down, you see the flame from the fuse. If you have to hold it down more than a second, then you begin to wonder if you have a dead short. Or you might end up pushing the button several times to try and get it to heat up.

It is also important for the wire to actually break and for the circuit to be broken. This added confirmation that the item actually fired. If you push the fire button, and it stays lit, you have to quickly figure out what item it was suppose to fire and then look out on the fire zone to see if the item really fired or not.

BTW the melting point of most types nichrome wire is around 1200-1400C. The actual temperature varies with what sort and percentage of other metals are part of the wire.

I usually use 31 gage because I found a a life time supply (3-4 mile roll) real cheap in a surplus store. It is a bit thicker than I prefer, but it works okay. I prefer 35-36 gage. 38 gage and higher feels to me like your wrapping human hair around the fuse. It is just too thin for my liking and it seems like it does not stay put as well at the thicker gage wire.

[wakanga]

thanks joe for the answers..i just want to have some advices before i put my project on it's actual testing...you're so lucky there that you have all your consumables or supplies available locally unlike here in the philippines it is so hard to find some of my needed supplies...BTW if ever the nichrome wire don't have a labeling for its gauge how will i know it??is there any alternative way of knowing the gauges? thanks again and Merry Christmas to all of you!

[JoeRatman]

Well if you take about a foot of the nichrome wire, you can measure how much resistance it has with an ohm meter. Higher resistance (ohms) means thinner wire.

Gage Ohms/foot
18 0.37
20 0.589
22 0.936
24 1.49
26 2.37
27 2.99
28 3.76
30 5.98
32 9.52
34 15.1
36 24.1
40 60.8

These values are based on nichrome. If there are different alloys in it, it will effect the resistance. For example, the stuff I have is called "EvenOhm" which is nichrome in a certain percentage and other metals. But it is 31 gage and is rated at 9.94 ohms per foot. This is higher than the above table.

I suppose another way to figure out the size, is to use a micrometer and measure the diameter of the wire. Once you know the diameter, you can figure out the gage.