26 SB3-5TL-21-BE-en-10 Operating Manual
6 Electrical Connection SMA Solar Technology AG
6.3 AC Connection
6.3.1 Requirements for the AC Connection
Cable requirements:
☐ External diameter: 12 mm to 21 mm
☐ Wire size: max. 10 mm2
☐ Insulation stripping length: 12 mm
☐ The cable must be dimensioned in accordance with the local and national directives for the
dimensioning of cables. The requirements for the minimum wire size derive from these directives.
Examples of factors influencing cable dimensioning are: nominal AC current, type of cable,
routing method, cable bundling, ambient temperature and maximum desired line losses
(for calculation of line losses, see design software Sunny Design from software version 2.0
www.SMA-Solar.com).
Load-break switch and cable protection:
WaHiw_Schraubsicherungen als Lasttrenneinrichtung
☐ In PV systems with multiple inverters, protect each inverter with a separate circuit breaker.
Make sure to observe the maximum permissible fuse protection (see Section 13 "Technical
Data", page 53). This will prevent residual voltage being present at the corresponding cable
after disconnection.
☐ Loads installed between the inverter and the circuit breaker must be fused separately.
Overvoltag e category
Overvoltage category
The inverter can be deployed in grids of installation category III or lower, as defined under
IEC 60664-1. This means that the inverter can be permanently connected at the grid-connection point
in a building. In installations involving long outdoor cable routes, additional measures must be taken
so that the overvoltage category is reduced from IV to III (see Technical Information "Overvoltage
Protection" at www.SMA-Solar.com).
Residual-current monitoring unit:
☐ If an external residual-current device is required, install a residual-current device which trips at a
residual current of 100 mA or higher (for details on selecting a residual-current device,
see Technical Information "Criteria for Selecting a Residual-Current Device" at
www.SMA-Solar.com).
Damage to the inverter due to the use of screw-type fuses as load-break switches
Screw-type fuses (e.g. DIAZED fuse or NEOZED fuse) are not load-break switches.
• Do not use screw-type fuses as load-break switches.
• Use a load-break switch or circuit breaker as a load disconnection unit (for information and
design examples, see Technical Information "Circuit Breaker" at www.SMA-Solar.com).
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