Noob here.

I have an cat5 cable and a romex cable already in place, which is great if I needed ethernet and power. If I twist the wires into two bundles, treating the bundles as one wire, and run 12v dc at 100amps through it? how would I know how much heat the wires would make?



Thanks again, in advance, and rest assured: I'll rtfm proper someday.

 

100 amps should be more than enough to melt the wires. When the house is on fire, the exact heat from the wires will be academic.

 

Calculate the DC resistance of each wire and then calculate the current in each wire.

Use (I^2)*R to find the dissipated heat per second.