The fusing of electrical installations is one of the most important points for safety on board.
The standard DIN EN ISO 10133 describes the electrical DC installation. One of the most important points, in addition to the familiar fusing of individual consumer feed lines on switchboards, is the fusing of all main lines directly at the battery. A functioning fuse protection concept provides for initial fusing as close as possible to the battery (main fuse). The large cross-sections connected directly to the battery are capable of carrying high currents in the event of a short circuit. The energy released in the battery and the cables quickly leads to overheating and subsequent fire. Even a small starter battery has enough stored energy to set a large yacht on fire. Therefore, care must be taken to ensure that the cable from the battery to the first fuse is as short as possible and is mechanically protected. The diagram opposite shows the fuse structure directly at the battery system.
All outgoing cables leading to the control panel, charger, windlass, measuring instruments, heaters, etc. must be fused according to the respective cable cross-section. For example, a fuse of 50 A is used for the control panel supply line with 16 mm2. The subsequent smaller cross-section cables leading to the consumers are fused on the control panel, so that these do not have to be taken into account when determining the supply cable fuse. The main battery switch for disconnecting the on-board power supply is installed near the battery.
Safety-relevant consumers, such as the bilge pump, alarm system or the memory supply for important navigation instruments, are connected directly to the battery to prevent accidental disconnection. These lines are also fused according to their cable cross-section. Automatic circuit breakers are recommended for fusing, but suitable strip fuses can also be used as an alternative.
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