enphase M250 Installation And Operation Manual page 32

Enphase Microinverter Installation and Operation

Minimise the number of unused Engage Cable connectors with three-phase systems. When
cable connectors are left unused on a three-phase system, it creates a phase imbalance on the
branch circuit. If multiple cable connectors are skipped over multiple branch circuits, the
imbalance can multiply.
You can sometimes avoid skipping Engage Cable connectors by using Engage Couplers. Use
the Engage Coupler to connect two Engage Cables or to connect Engage Cable to field cable.
There are many possible scenarios for each type of connection, but they generally fall into four
categories:
Engage Cable to Engage Cable:
1. Make use of leftover lengths of Engage Cable
2. Transition between portrait and landscape Engage Cable
Engage Cable to Field Cable (such as Engage Cable, H07BQ-F, U-1000 RO2V, FG7OR,
NYY-J)
3. Transition between sub-arrays on the same circuit
4. Create wiring extensions for Engage Cable
In situations where you cannot use an Engage Coupler, you can use an electrical junction box to
transition between cable types.

Account for additional lengths of cable when calculating total voltage rise (voltage drop).
Refer to the Technical Brief on Voltage Drop at http://www.enphase.com/support.

Plan for additional length to reach from one row of PV modules to the next. If the PV
modules are laid out in multiple rows, the distance from one row to the next often requires
additional cabling length.

Account for looping. When planning cabling turns or loops, do not form loops smaller than 12
cm in diameter.

Consider additional cabling when installing multiple sub-arrays. Often, an AC branch circuit
may be composed of several smaller sub-arrays across more than one roof plane. In this case,
cut the cable to service each smaller array, and connect the sub-arrays together using and
Engage Coupler, or an appropriately rated AC junction box and conduit. Accomplish the
transition from cable to conduit as required by local standards. Cover unused connectors with
Enphase sealing caps.

Account for any mixture of PV modules in both portrait and landscape orientation. When
PV modules are installed in mixed orientation (both portrait and landscape orientation), there are
three choices for cabling:
1. Cabling with 1.025-metre spacing between connectors results in cleanest install for the
PV modules in portrait orientation. For PV modules placed in landscape orientation, plan
for an unused connector between each PV module to accommodate the required
additional distance. Cover unused connectors with Enphase watertight sealing caps.
2. Cabling with 1.7-metre or 2.11-metre spacing between connectors results in cleanest
install for PV modules in landscape orientation, but requires that any additional cable
length between PV modules in portrait orientation be coiled and dressed so that cabling
does not contact the roof. Cover unused connectors with Enphase watertight sealing
caps.
3. Transition between 1.025 and 1.7-metre or 2.11-metre spaced cable using an outdoor-
rated junction box. Install this junction box to the PV racking.
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141-00024 Rev 02b