RKM code

The British standard BS 1852 and its replacement, BS EN 60062, comprises a colour code for fixed resistors; letter and digit code for resistance (R for ohms, K for kilohms and M for megohms) and capacitance values.

Codes

Letter code for resistance and capacitance tolerances and a date code for capacitors and resistors:

coding:

BB - 1/8 WATTS,

CB - 1/4 ″ ,

EB - 1/2 ″ ,

GB - 1/1 ″ ,

5 - ±5% tolerance,

2 - ±20% ″,

1 - ±10% ″,

Steps to find out the resistance or capacitance values:

1. 1st 2 letters gives the power dissipation capacity.
2. next 3 digits gives the resistance value.
   1. 1st 2 digits are the significant values
   2. 3rd digit is the multiplier.
3. final digit gives the tolerance.

Examples

If a resistor is coded :

• EB1041: power dissipation capacity = 1/2 watts, resistance value = 10×10^4±10% = between 9×10^4 ohms and 11×10^4 ohms.
• CB3932: power dissipation capacity = 1/4 watts, resistance value = 39×10^3±20% = between 46.8×10^3 ohms and 31.2×10^3 ohms.

Examples of resistance values
R47	0.47 ohm
4R7	4.7 ohm
470R	470 ohm
4K7	4.7 kilohm
47K	47 kilohm
47K3	47.3 kilohm
470K	470 kilohm
4M7	4.7 megohm