# Electronic – How to calculate the power rating for zero-ohm resistors

currentcurrent measurementmaximum-ratingspowerresistors

Based on my earlier question, since there supposed to be zero voltage (V=IR) drop across a 0 Ω resistor, how do we select the power rating of such a component?

For example, let's say I were to connect a zero-ohm resistor in between 5 V power source and a load (circuit variant) which take current ranges from 20-200 mA. What is the power rating of the 0 Ω resistor I should select?

Yageo specifies both maximum current and maximum power, see page 5 of the datasheet:

\$P_{max}\$: 100 mW
\$I_{max}\$: 1 A

and you'll also see that for the jumper

\$R_{max}\$: 50 mΩ

That seems inconsistent: 1 A through 50 mΩ is only 50 mW, not 100 mW. In these cases you have to work with the lower value: 50 mW, since 100 mW would mean a 1.4 A current, which exceeds the 1 A limit.

EEs often scoff at the 5 % tolerance specification for the 0 Ω resistor. The engineers at Yageo know that that doesn't make sense, and if you take a good look at page 2 you'll see that they don't specify 5 % for the jumper at all:

F = ± 1 %
J = ± 5 % (for Jumper ordering, use code of J)

which should be read as "we use the same code for a jumper as the tolerance for other values". It does not implied that the 5 % tolerance would apply to the jumper.

Specifying maximum power isn't silly either: the part's weight and specific thermal capacity determine that, regardless of resistance value.