Installation manual

© 2014 EcoInnovation Ltd (NZ) Page 71
On a 12/24 VDC battery systems, earthing of the bulkhead may not be required.
 Where the hydro turbine is close to the power shed, a green earth wire from the
turbine bulkhead must be connected to the main earthing rod via the equipment
earthing.
 Where the hydro turbine is distant to the power shed, the turbine bulkhead should be
connected to a local earthing rod. You may be able to rely on this rod for earthing or
you may also need an earth wire in your supply cable. Please check your local
wiring rules as some jurisdictions advise only one earth rod location.
In cases where an earthing rod can be local to the hydro turbine this represents a significant
cost saving in wire and it may be safer, as long cables are much more likely to be
accidentally cut than a short local one. In these cases the long run earth wire can be
replaced with a short wire as shown. But you must ensure that the impedance of the
connection (whether by wire or by direct earth electrode) is low enough that the bulkhead
cannot be at a dangerous voltage when there is a fault current to earth.
6.2.6. Important note for grid connected systems
Grid connected versions of the PowerSpout have EMC output filters
fitted. Unless legally obliged the DC turbine output (inverter input)
should not be tied to earth, or EMC performance may be compromised.
The bulkhead should be earthed in every case as it is not connected to
the output wiring.
6.2.7. Earth cable size
PowerSpout hydro turbines are fitted with 2m long earth leads depending on the maximum
current rating of the turbine:
 2.5 mm
2
< 16 amp
 4 mm
2
< 32 amp
 6 mm
2
< 50 amp (upgrade fee applies)
6.2.8. Earth Rod (electrode size)
An earth rod driven 1.8m into the ground may be sufficient, but always check your local
codes. You may also need to measure the impedance to ensure safety.
Earth rods are typically made of the following materials:
 16mm diameter hot dipped galvanised steel
 20mm diameter hot dipped galvanised steel pipe
 15mm copper pipe 2.5mm thick
6.3. Ground-fault protection for PV and DC hydro systems
In the USA the National Electrical Code (NEC) Article 690.5 states ground-fault
protection requirements for grounded DC solar PV systems. Ground fault
protection is also required for ungrounded systems detailed in 690.35(C). The
purpose of ground-fault protection devices (GFPD) is to reduce the risk of fire
associated with a ground fault. If the ground fault is a short-circuit, the fault current can be
high, which creates a significant fire hazard.
Because of this fire hazard, ground-fault protection circuits are required for roof-mounted
residential PV installations, where the risk of fire is greater than a system mounted in a field