Quote from: Loudthud on June 27, 2016, 03:56:00 PM
In a series circuit, the resistor with the highest resistance will have the most dissipation. Calculate the current that will result in that resistor being at it's maximum, then check that the other resistors will be at or below their rating at that current.
In a parallel circuit, the resistor with the lowest resistance will dissipate the most power. Calculate the Voltage that will result in that resistor being at it's maximum, then check that the other resistors will be at or below their rating at that Voltage.
As a practical matter, running resistors at their maximum power rating is not a good idea. If they are on a PCB, it will usually make the board turn black. The resistor or it's solder joints will fail. A resistor's power rating is based on temperature. If they are in a warm environment, they must be de-rated. You can run resistors beyond their power rating for short amounts of time as long as the resistor does not get too hot. To be conservative, don't run resistors more than about half their power rating.
Thanks everyone.
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