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

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 7 of this manual. You must protect each microinverter AC branch circuit with a
20A maximum breaker.
a. Size the AC cable/wire size to account for voltage drop. Select conductor diameter based on the
distance from the beginning of the microinverter AC branch circuit to the breaker in the AC mains.
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, Voltage Drop Considerations for M215, at
http://www.enphase.com/support/downloads.
b. Install an appropriate junction box at a suitable location on the mounting system. You can centre
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 electricity network connection
using equipment and practices as required by local jurisdictions.
10 Copyright © 2012 Enphase Energy
M215 Installation and Operation
141-00021 Rev 01