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DC FUSES

To protect the DC wiring from overloading, fuses need to be used as

overloaded cables or wires can cause fire and hazardous situations.

Overloaded wiring can be caused by faulty equipment or by simply too much

equipment connected to the same wiring. Ingress of water in the navigation lamps is

an example of a possible overload.

A fuse protects the cable, not the connected equipment. Usually a fuse will be installed

with a slightly lower value than the cable allows. The table below provides an overview

of the maximum current without overloading the cables, plus the required value of the

fuse. For example, a cable of 6 mm² has a maximum load of 50 amperes so the value

of the fuse should be 50 amperes at most. Installing a larger fuse would be dangerous

as it could cause the cable to ignite. A smaller fuse can result in unnecessary failure of

the connected equipment.

There are many fuses available and the most common for smaller loads is the ATO/

ATC (car type) fuse. This fuse can protect wiring up to 2.5-4 mm². Although these fuses

are available with a rating of more than 30 amps, this will not be recommended as the

heat production will be high and a premature failure of the fuse might be expected.

For higher loads or loads that are continuously powered, so called ANL or plate fuses

will often be installed. These fuses are commonly used for currents of approx. 20 to

100-125 amps, but higher ratings are available. For more professional or high power

installations, like for example winches or bowthrusters, often the NH (knife type) or

T-fuse will be installed. Although these fuses are sometimes, due to their physical size,

not easy to install, they are very reliable. They are commonly used for currents of

50 amps and more.

ATO fuse. ATC fuse.

ANL fuse.

NH fuses (knife type).

T-fuse.

DC fuses

wire size

max. current

fuse required

preferred type

0.75 mm

2

12 A

10 A

ATO/ATC (car type)

1 mm

2

18 A

15 A

ATO/ATC (car type)

1.5 mm

2

21 A

20 A

ATO/ATC (car type)

2.5 mm

2

30 A

30 A

ATO/ATC (car type)

4 mm

2

40 A

40 A

ANL Blade type

6 mm

2

50 A

50 A

ANL Blade type

10 mm

2

80 A

70 A

ANL Blade type

16 mm

2

100 A

100 A

NH (knife type) or T-fuse

25 mm

2

140 A

125 A

NH (knife type) or T-fuse

35 mm

2

185 A

160 A

NH (knife type) or T-fuse

50 mm

2

230 A

224 A

NH (knife type) or T-fuse

70 mm

2

285 A

250 A

NH (knife type) or T-fuse

95 mm

2

330 A

315 A

NH (knife type) or T-fuse

120 mm

2

400 A

400 A

NH (knife type) or T-fuse

150 mm

2

430 A

425 A

NH (knife type) or T-fuse

240 mm

2

710 A

630 A

NH (knife type) or T-fuse

Please note that fuse and cable ratings are subject to local regulations,

consult your supplier for more detailed advice and installation.

n

NOTE

When charging batteries, other criteria are applicable for selecting the correct

cable sizes (see also page 175).

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