2-11
which means the fuse should be used in a circuit where the voltage is 250 volts or less. After this is a set
of three numbers and the letter "R," which represent the current rating of the fuse. The "R" indicates the
decimal point. In the example shown, the current rating is 1R00 or 1.00 ampere. Some other examples of
the current rating are shown in the current code table of figure 2-8. The final letter in the old military
designation (A) indicates the time delay rating of the fuse.
While the old military designation is still found on some fuses, the voltage and current ratings must
be "translated," since they use letters to represent numerical values. The military developed the new
military designations to make fuse identification easier.
NEW MILITARY DESIGNATION
Figure 2-9 is an example of a fuse coded in the new military designation. The fuse identified in the
example in figure 2-9 is the same type as the fuse used as an example in figure 2-8.
Figure 2-9.—New type military fuse designation.
The new military designation always start with the letter "F," which stands for fuse. The set of
numbers (02) next to this indicates the style. The style numbers are identical to the ones used in the old
military designation and indicate the construction and dimensions of the fuse. Following the style
designation is a single letter (A) that indicates the time delay rating of the fuse. This is the same time
delay rating code as indicated in the old military designation, but the position of this letter in the coding is
changed to avoid confusing the "A" for standard time delay with the "A" for ampere. Following the time
delay rating is the voltage rating of the fuse (250) V. In the old military designation, a letter was used to
indicate the voltage rating. In the new military designation, the voltage is indicated by numbers followed
by a "V," which stands for volts or less. After the voltage rating, the current rating is given by numbers
followed by the letter "A." The current rating may be a whole number (1A), a fraction (1/500 A), a whole
number and a fraction (1 1/2A), a decimal (0.250A), or a whole number and a decimal (1.50A). If the
ferrules of the fuse are silver-plated, the current rating will be followed by the letter "S." If any other
plating is used, the current rating will be the last part of the fuse identification.
