STRCOM Fused String Combiners
Installation and Operation Manual
DOC-020040 rev 4.4
12
points for array equipment ground conductors depending on the string combiner
model:
String Combiner Version
positions
wire size
Torque
4-12 fuse
30 (2/lug)
14-12 AWG
25 in-lb
or
15 (1/lug)
12-10 AWG
20 in-lb
(1/lug)
8 AWG
25 in-lb
(1/lug)
6-4 AWG
35 in-lb
and 1
6AWG – 2/0
50 in-lb
13-30 fuse
50 (2/lug)
14-12 AWG
25 in-lb
or
25 (1/lug)
12-10 AWG
20 in-lb
(1/lug)
8 AWG
25 in-lb
(1/lug)
6-4 AWG
35 in-lb
and 1
6AWG – 2/0
50 in-lb
and 2
6AWG - 250KCM
275 in-lb
Lightning and Surge Protection:
The inverter used with the PV system must be listed to UL1741/IEEE1547 and
include required lightning and surge protection. It is a good practice to add additional
lightning and surge protection on inverter or system DC disconnects. The lightning
arrester can also be installed on the combiner but must be done in a way that
maintains the NEMA4 rating of the combiner if outdoors. Lightning arrester leads
should be connected to:
1-
a ground bar terminal
2-
a lug on the inverter side of the positive (+) fuse bus (you need to add an
appropriate lug for this to an available hole on the fuse bus.
3-
one of the array terminal screws on the negative (-)terminal block.
Grounding Electrode Conductor:
As with all PV systems, a Grounding Electrode Conductor must be installed per
UL690.47 (and 250.166). This conductor should be sized according to these NEC
requirements.
To disconnect the inverter from the building/utility grid, turn off the DC disconnect, then the AC
disconnect. Turn off the AC 3-phase building/utility breaker if needed.
