I can use a higher gauge wire with the same wattage if I use a higher voltage so the current is lower. Can I do the same with resistors? I have a neon sign transformer that’s 450 watts at 15 kV and 30 mA. Now on the wire gauge chart with this low amount of current I’m able to use very thin wires. Does this mean I can use like a 1 watt resistor for my 450 watt transformer at 15 kV and 30 mA? The 1 watt resistor wires gauge is thick enough to handle an even higher current than 30 mA. It has to work this way right?

  • \$\begingroup\$ what do you mean by higher gauge wire? \$\endgroup\$
    – jsotola
    May 15 at 2:49
  • \$\begingroup\$ The higher the gauge wire the thinner it is. The lower the gauge wire the thicker. Since my power source is high voltage and low current can I use smaller wattage resistors than the wattage of my power supply? The lower my current the thinner the wire I can use \$\endgroup\$
    – Electrode
    May 15 at 2:53

1 Answer 1


Ohm's Law is your friend. $$P = I^2R$$

If you know the current and resistor value you can find how many watts it will dissipate, and then select one that gives some safety margin, at least 1 1/2 times the calculated wattage.

For high voltage you also have to take into account the voltage rating of a resistor. Again use Ohm's Law to find the voltage and allow a safety factor. $$E = IR$$

  • 1
    \$\begingroup\$ As an addendum to this, many resistors don't list a voltage rating. If there is no voltage rating listed, assume it's lower than 30 V--look for resistors that do have a voltage rating. \$\endgroup\$
    – Hearth
    May 15 at 2:21

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