enphase ET10-208-30, Руководство по установке

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Page 13 Copyright Enphase Energy Inc. 2011 141-00013 Rev 03b
Step 2 – Install the AC Branch Circuit Junction Box
Risk of Electrical Shock . Be aware that installation of this
equipment includes risk of electric shock. Do not install the
junction box without first removing AC power from the
Enphase System.
Use electrical system components approved for wet locations
only.
When stripping off the cable sheath, make sure that the
conductors are not damaged.
Do not weigh down the cabling system.
Loose cables might become a tripping hazard. Attach the
power cables correctly.
Do NOT exceed the maximum number of microinverters in an
AC branch circuit as listed on page 7 of this manual, and
protect each microinverter AC branch circuit with a 20 A
maximum breaker.
a. Size the AC wire gauge to account for voltage drop. Select the correct
wire size based on the distance from the beginning of the microinverter
branch circuit to the breaker in the load center.
All components of system wiring must be considered, including internal
voltage drop within the length of Engage Cable. Typically, three wire
sections and several wire terminations must be quantified. There is
also some resistance associated with each OCPD (OverCurrent
Protective Device), typically a circuit breaker. As all of these
resistances are in series, they add together. Since the same current is
flowing through each resistance, the total voltage drop is total current
times the total resistance. For a split-phase system, the total
resistance is equal to two times the one-way resistance. For a three-
phase system, each of the three line currents and resistances must be
calculated.
NEC guidelines for voltage drop on feeder and branch circuit
conductors will not be sufficient for microinverter branch
circuits that contain the maximum allowable microinverters.
This is due to high inherent voltage rise on the branch circuit.
For more information, refer to the
Voltage Drop Calculations Application
Note at http://www.enphase.com/support/downloads .
b. Install an outdoor rated, weather-proof junction box at a suitable
location on the PV racking system (typically at the end of a row of
modules).
c. Provide an AC connection from the junction box back to the utility
interconnection, using equipment and practice as required by the NEC
and local jurisdictions.