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Nichrome Amp Calculation???

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SMUGangsta

New Member
Hi

Just a quick one,

I am trying to figure out the current used by my nichrome wire.

Is is 50Ω per 1000mm (1m) - is this a normal ohms law thing?

im using 30mm

V=I×R

so re-arranged to find I would be

I=V/R

I = 12v/1.5Ω

So the nichrome draws 8Amps as a heating element. <<<is this right?

Will the resistance of the wire change as it heats up, I would like to switch it with a 10A relay.

Thanks
 
Your calculation is correct, but 8 amps is 96W which would likely melt a 30mm wire (you have a fuse). Estimating that you wire is 34 gauge, I believe you should limit the current to about 2 amps.

The wire will increase about 6-10% in resistance as it heats to a red heat.
 
Hi

Just a quick one,

I am trying to figure out the current used by my nichrome wire.

Is is 50Ω per 1000mm (1m) - is this a normal ohms law thing?

im using 30mm

V=I×R

so re-arranged to find I would be

I=V/R

I = 12v/1.5Ω

So the nichrome draws 8Amps as a heating element. <<<is this right?

Will the resistance of the wire change as it heats up, I would like to switch it with a 10A relay.

Thanks
Yes, 30/1000 = 3/100 = 3% of 50Ω = 1.5Ω.
The resistance tempco of Nichrome is pretty low.
If this skinny wire is inside a 1/4" metal tube embedded in ceramic, or under water, it can dissipate quite a bit of power.
 
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