# Resistor

Discussion in 'The Projects Forum' started by kfrazie1, Mar 30, 2010.

1. ### kfrazie1 Thread Starter New Member

Jan 4, 2010
23
0
What happens to the power rating of a resistor when it is added in either series or parrallel. I need a .15 ohm resistor with a power rating of about 250 watts so I figured I would make some sort of parrallel/series combination of resistors.

2. ### Wendy Moderator

Mar 24, 2008
21,839
3,051
If you split the load you double the wattage. It is a good way to do what you are wanting.

Figure the power by the voltage each resistor drops and its resistance, on a one by one level.

3. ### Bychon Member

Mar 12, 2010
469
42
Technically speaking, the power rating of a resistor does not change when it is added to other resistors. The power rating of each of the many resistors add together.

4. ### alim AAC Fanatic!

Dec 27, 2005
113
2
Hi just a small point , wattage of resistors add whether in series or in parrallel. Lets say you have 2 100 ohms 1watt in series they become 200 ohms 2watts, however if the values are not equal and they are expected to dissipate an equal share, that would not occur. For example, if you place a 100 ohm 1 watt in series with a 20 ohm 1 watt, it is not safe in practice, if the expected dissipation is 2 watts, the 100 ohm would be required to dissipate 5 times that of the 20 ohms