Figure 2-31.--Type EL-1 fuse holder.

holders, separate indicator light circuits are mounted

therefore be used to fuse both sides of the line, or, in

on a panel and connected in parallel with separately

conjunction with a type FHL11G, will fuse a 3-phase

mounted fuses and fuse clips. In some cases an alarm

line. Type FHL12G will accommodate 1 1/2- by 13/32-

circuit in the form of a bell or buzzer takes the place

inch fuses. When these fuse holders are mounted in a

of the indicator light.

dripproof enclosure, they maintain the dripproof

integrity. They also possess the ruggedness and the

vibration and high-impact shock resistance necessary

Troubleshooting Fuse Circuits

for shipboard use.

An electrical system may consist of a

The extensive use of low-voltage power supplies

comparatively small number of circuits or, in the

has required the use of incandescent lamps in place of

larger systems, the installation may be equal to that

neon glow lamps in some indicator light circuits. A

of a fair-sized city.

modification of the FHL10U fuse holder provides a

third terminal connected to a 28-volt incandescent

Regardless of the size of the installation, an

lamp in the cap. By insertion of a suitable resistor

electrical system consists of a source of power

between the load terminal and the added terminal,

(generators or batteries) and a means of delivering

the lamp will be energized by a sufficient voltage to

this power from the source to the various loads

become visible when the fuse has blown. In some low-

(lights, motors, and other electrical equipments).

voltage fuse holders the resistor and lamp are

included within the clear plastic cap. Low-voltage

From the main power supply the total electrical

fuse holders should not be used in sensitive, low-

load is divided into several feeder circuits, and each

current equipment. Where an overload condition

feeder circuit is further divided into several branch

occurs and the fuse blows, the low-resistance

circuits. Each final branch circuit is fused to safely

indicator circuit may pass sufficient current to

carry only its own load, while each feeder is safely

damage the equipment.

fused to carry the total current of its several

branches. This reduces the possibility of one circuit

Due to the design of certain fuses and in cases

failure interrupting the power for the entire system.

where space does not permit indicator-type fuse

The feeder distribution boxes and the branch

distribution boxes contain fuses to protect the various

circuits.

The distribution wiring diagram showing the

connections that might be used in a lighting system is

140.13

Figure 2-32.--Type FHL12U fuse holder.

Figure 2-31.--Type EL-1 fuse holder.

2-21