# Short Circuit Fires

I understand that if there’s low resistance, Ohm’s law shows that the current drawn will be very high. However, isn’t resistance what causes heat in a wire? I get there’s a lot of current going through the wire in a short, and there’s lots of power, but since there’s low resistance how does the energy get transformed into heat? How does a spark or fire start?

• Joules can be written as $P=V^2/R$, so the lower the resistance the higher the power dissipated. If the material can't dissipate the heat, it will get very hot and can burn. – jinawee Nov 1 '15 at 11:06
• you are wrong to say lower resistance means high power dissipation. connecting wires have negligible resistance but still power dissipation is very low. – Anubhav Goel Nov 1 '15 at 11:38
• @jinawee What causes the energy of the current to be transformed into thermal energy within the wire, though? I get that heat is not dissipated to the surroundings, but what’s the mechanism for the transformation to thermal energy of the circuit’s electrical energy? – lightweaver Nov 1 '15 at 11:54