Step 2 - Install The Ac Branch Circuit Junction Box - enphase M215 Installation And Operation Manual

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Step 2 – Install the AC Branch Circuit Junction Box
DANGER: Risk of Electrical Shock. Be aware that installation of this equipment includes risk
of electric shock. Do not install the AC junction box without first removing AC power from
the Enphase System.
WARNING: Only use electrical system components approved for wet locations.
WARNING: Do NOT exceed the maximum number of microinverters in an AC branch circuit
as listed on page 27 of this manual. You must protect each microinverter AC branch circuit
with a 20A 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 AC 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 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 single-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.
Standard guidelines for voltage drop on feeder and AC branch circuit conductors might not be
sufficient for microinverter AC branch circuits that contain the maximum allowable
microinverters. This is due to high inherent voltage rise on the AC branch circuit.
For more information, refer to our Technical Brief,
b. Install an appropriate junction box at a suitable location on the PV racking system. You can
center feed the branch, or you can install
the junction box at the end of a row of PV
modules.
c. Provide an AC connection from the AC
junction box back to the electrical utility
connection using equipment and
practices as required by the NEC and
local jurisdictions.
10
Copyright  2012 Enphase Energy
M215 Installation and Operation
Voltage Drop Considerations for
M215.
141-00012 Rev 04

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