Installation manual

6. System Wiring

This section covers the items you will need to safely wire the components of your system

together. There are wiring diagrams to cover all typical system configurations.

For electrical safety you need to protect against fire and shock hazards.

6.1. Fuses and Circuit Breakers

Batteries are very unlikely to give you an electric shock because their

voltage is low, but a battery is a source of energy that can deliver

thousands of amps of current into a short circuit that will turn wire red hot.

Any circuit that comes from a battery should be protected by fuses or

circuit breakers that will never trip under normal operating currents, but that will trip or blow

before the safe operating current of the wiring is exceeded. High rupture capacity (HRC)

fuses are preferred where very high currents can arise from large batteries.

Fuse ratings will be dependent on the overall power rating and type of components in your

system. Different circuits use different currents and different wires sizes and need different

fuses/breakers. When a fuse blows or a breaker trips due to a fault in one circuit, only that

individual circuit should be isolated from the battery.

If the turbine is directly connected to the battery without an MPPT controller then you must

take care to never disconnect the battery from the system as a whole. By all means

disconnect all of the individual circuits but keep the turbine circuit separate from the others

as it is likely to damage the connected equipment with its high open circuit voltage (Voc).

In order to prevent system damage through shorts and

malfunctions, and for general ease of maintenance, it is

recommended that a number of fuses or breakers be placed in the

system for protection. If an overcurrent occurs they will break the

current path. If a "live" wire touches the earthed metalwork in the

system then this will also create a fault current which will trip the

protection and isolate the faulty circuit.

6.1.1. Circuit Breakers

Breakers are another good way to protect against over-current in the

wiring. Take care to use DC rated breakers on DC circuits, because AC

breakers may not be able to handle the arc. Modern Non-Polarized DC

breakers are common, mainly thanks to the large solar PV industry.

Until recently Polarized DC breakers were also common. Such

breakers can normally be identified by the “+” sign at one of the two

ends, as can be seen in the picture. This type

of breaker has been outlawed in many

countries as it has caused fires when installed

incorrectly. Avoid this type of breaker on new

installations.

6.1.2. Common DC Breaker sizes

Due to the large solar PV industry, non polarised 2-pole (500 VDC) and 4-pole (1000 VDC)

are very common and affordable. Single pole are also available.

Main battery HRC fuse

holder