Standard Series Resistors E6, E12, E24

Components used in electrical engineering like resistors (or e.g. capacitors) cannot be manufactured in all manner of gradations, but must be produced to specific values, i.e. values in a standard series. The various standard series are classified as E6, E12, E24, E48 and E96. The number indicates the number of available values per decade (i.e. between 1 ... 9, 10 ... 99, 100 ... 999 etc.).

The tolerance is also incorporated into the standard series. Here for example the series E6  has a tolerance of ±20%, the series E12 has a tolerance of ±10% etc. The greater the tolerance of a standard series, the fewer the resistance values contained in it. This tolerance is also the basis for the gaps between the individual values. These have been staggered in such a way that one value's positive tolerance overlaps slightly with the negative tolerance of the next value.

Example: 10 W + 10% = 11 W
  12 W - 10% = 10.8 W

The table lists the values of the most important standard series E6, E12 and E24. The specified decimal values always refer to the first two colour rings of the resistor.



As you can see the series E12 contains only every second value included in series E24 and series E6 only every second value included in series E12. A resistor of 150 W, for example, is thus available in all series (i.e. with every tolerance), but a resistor of say 5.6 kW is only available in series E12 and E24.

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