Which nichrome wire should I choose for my project ?

I am working on an electric igniter using nichrome wire. Its my first time with NIchrome so I dont have any idea about it. I have some nichrome wire out of trash but I dont know the amount of voltage and current required to heat it up. It would be very helpful of you guys if you help me with this.

Please tell me the voltage and current required to heat it up and the battery to be used. (Maybe hot enough to turn it red)

Jack A Lopez3 months ago

You should also look in the, "related panel", on the right there, if you have not done this already.


This site seems to have a large number of members who are pyromaniacs, and there are already quite a few 'ibles on the subject of homemade electric matches, firework igniters, etc. Perhaps by looking at a few of these, you can find some insight regarding the things you want to do with nichrome wire.

Downunder35m3 months ago

My friends might have given the proper info but I guess for you it is total overkill of information ? ;)
I'll try to make it simple:
The longer the wire the higher is the resistance from end to end.
A thick wire means lower resistance, a thin wire means higher resistance.
So much for the pure basics.
For an igniter you need very high temperatures, this makes the wire very brittle.
Once it was hot enough the wire should no longer be put under any mechanical stress!
So no bending around used wire that is clearly discolored, even if the new bend seems to be fine it will soon fail during operation conditions.
To get high temperatures out of a heating wire without temperature control means you need a power supply that is suited to heat the wire to the required temp without burning it out.
This can be done in two ways.
a) trial and error if you enough wire to spare...
b) measuring...
I will go into b) soon...

Unless you need a really big igniter you should go as small as possible, especially if you plan on battery operation.
A single strand of wire requires a very low voltage and very high currents to get to a glowing red temperature.
The thinner the wire the lower are the power reuirements here but the higher the risk of the wire burning out prematurely.
A good way to compensate is using the same old trick used in incandescent lightbulbs: coil it up!
A thin coil of thin nichrome wire gives you a few advantages:
1. the resistance higher
2. less power is required to heat the same lenght of ignition area
3. the wire can expand and contract in the coiled spring and will last much longer

How to it right though?
You will need a roll of nichrome wire if measuring and calculating is not your thing.
Get really thin wire, coil it to a tight spring (a fine pitched screw works great here or a toothpick) and see what happens when connected to power.
You need a good enough power supply for heating wire!
Don't even think about 9V batteries or AAA's ;)
If the coil goes red hot right away you need a longer wire or stretch the coil carefully.
If the coil goes only warm the wire is too long, try reducing the length by tapping into the coil until you find the spot where the wire gets to the desired temp.
Unwind and straighten the wire without pulling and measure the lenght for future reference.
Make a new coil based on your measurements and enjoy.
If you know how to use Ohms law and a calculator you can match the wire to your power supply.
Using the datasheet, manufacturers information or online charts for the type of wire you can get the resistance per meter or per km of wire.
You should leave some safety margin for the sake of your power supply when creating your heating element!
For example if you use a 12V/3A power supply then you want a wire that does not use more than 2.5A during operation.
Keep in mind that a tightly coiled wire will heat faster and much higher than a straight wire!
To be clear:
If 20cm of your wire get too hot to tough while straight then chances are a tight coil from the same 20cm lenght of wire will already start to glow.

In case you want to ignite other things than gas:
Nichrome wire is quite resistant but when igniting paper, wood, charcoal, cigarettes or fuses the wire will soon wear out and fail if not handled correctly.
For stability and longer life you might want to consider winding the wire around a magnesia stirring rod - available cheap from chemical or lab supplier and Ebay, ceramic is even better.
To prevent the wire from failing too early due to the contact with the ingition material you should use a two stage heating system.
Stage one is just hot enough to ignite what you need to ignite, stage two brings the wire to the full glowing red heat that it can safely tolerate.
You can simple use a two way switch and an addition straight lenght of nichrome wire to reduce the power for stage one.
Now you can ignite what you need at a low temperature and ignore the build up on the wire until is makes igniting too hard.
Now you go to stage two and burn the build up off.
A big blow through a straw should remove the ashes if the temp and duration was right.

rickharris3 months ago


You'r going to need to measure accurately the diameter of the wire you have and convert this to wire gauge.

You do not have to accurately measure the diameter, not if you have tools for measuring the wire's resistance per unit length, and ideally that could be done with a tape measure, and an ohmmeter.

If you can get a believable number for resistance per unit length, e.g. in ohms/meter, then you use a table, like the one in the Wikipedia article for "Nichrome", to discover what diameter of nichrome wire has that characteristic resistance per unit length, at room temperature.


Also note, not all resistance wire is made of nichrome. In fact the word, "nichrome", is in danger of becoming a synonym for "resistance wire". I think I even read, in an 'ible somewhere on this site, language like, "Kanthal is a kind of nichrome," or something ignorant like that. If only I could remember which 'ible it was.