Question about wattage of resistance in parallel

[Rotus623]

(First off, the question is not about the ohmage, it is about the wattage.) Obviously there is a simple formula to determine resistance in parallel. I need 330 ohms at 2W. I have all one watt resistors. Instead of running a 330ohm 2W resistor, could I run 3 1k 1W resistors in parallel? I figured since the power would be distributed through three 1W resistors the setup would easily handle the 2w that it needs to handle. Is this correct??

[BobEllis]

Yes, 3 paralleled 1K/1W resistors will give you 333R, at 3W. Dissipation in each resistor is V^2/R, which works even if they are not the same value.

Is your actual dissipation 2W or does your schematic call for a 2W resistor? If actually 2W, you probably want to go a bit higher than 3W capability. The usual rule of thumb is to use no more than 1/2 rated power dissipation.

[Rotus623]

Originally Posted by BobEllis

Yes, 3 paralleled 1K/1W resistors will give you 333R, at 3W. Dissipation in each resistor is V^2/R, which works even if they are not the same value.

Is your actual dissipation 2W or does your schematic call for a 2W resistor? If actually 2W, you probably want to go a bit higher than 3W capability. The usual rule of thumb is to use no more than 1/2 rated power dissipation.

Thanks Bob!! Great answer to my question. And thanks for the dissipation pointer also, but yes the schematic calls for 2W so 3W will be plenty!!