[ChuckE]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by sbmike:
... after a very short time, the resistor was almost too hot to hold in my hand. <HR></BLOCKQUOTE>

Right, resistors can get warm. That is their design. ALL resistors get warm, it is a function of their operation. The energy is dissipated in the from of heat. How much heat is a function of how much voltage is applied the resistance. If the power design of the resistor is exceeded, then the resistor will get dangerously hot, and could possibly burn either itself, or the surrounding material. Large wattage resistors are physically larger, so as the heat is dissipated over a larger surface.

If the power rating of the resistor is not exceeded then, while the resistor will still get warm, it should not be dangerous.

If the resistor is getting too hot to hold, then as a seat-of-the-pants guess, the power rating is being exceeded.

You must realize, though, that a 12 watt dissipation (as with a 12 ohm resistor, i.e. 12 volts and a 12 ohm resistor) is still 12 watts, no matter what the rating of the resistor is. If you put in a 1 watt 12 ohm resistor into a 12 volt circuit, it will dissipate 12 watts and subsequently burn up shortly.
Pretty much so, but not as quick, if you place a 5 watt resistor in that same circuit, since it will still dissipate 12 watts.
And also, in due time, even if you used a 10 watt resistor. 12 watts will get dissipated.
And while a turn signal would not be on at all time, and a 10 watt resistor would probably work for quite a long period of time (due to the abbreviated duty cycle, on-off-on-off etc.) it is just poor design to use a 10 watt resistor in such a situation (what would happen if something weird made the turn signal "stick" in the always on condition?). It is much better to over-exceed the power rating to keep things cooler to the touch.