SOB Manual

MNSOB Shut Off Box Instructions (continued)
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Introduction
The MNSOB series of Rapid Shutdown boxes are designed for indoor / outdoor use. Type 4X have been tested
to be watertight to 2 meters underwater, so they are sure to be watertight above sea level.
Overview of size/ratings:
MNSOB4X-2P ---- 2 position, Internal conductor rating 20A, Switch 100A per pole Continuous, NEMA 4X
MNSOB3R-2P ---- 2 position, Internal conductor rating 20A, Switch 100A per pole Continuous, NEMA 3R
MNSOB4X-4P ---- 4 position, Internal conductor rating 20A, Switch 100A per pole Continuous, NEMA 4X
MNSOB3R-4P ---- 4 position, Internal conductor rating 20A, Switch 100A per pole Continuous, NEMA 3R
Installation
Note: The deadfront is marked as a photovoltaic combiner. The Shut Off
Boxes do not act as a combiner, so do not get confused by this.
To remove the deadfront:
Note: The plastic dead front fits very tight. You must first remove the lid in
order to remove the deadfront.
On type 3R units, pry off the lid as shown using something like a
screwdriver as a lever. The dead front then lifts out easily.
On TYPE 4X units the deadfront is secured to a mounting bracket just
above the terminal blocks. To remove it, gently lift it out from the top.
To reinstall the deadfront on all units, press it gently into place. There will be a gentle snap when it seats.
The installation of a Shut Off Box is fairly straight forward. Select the location to install your Shut Off Box first.
the SOB's are used to disconnect the PV array within 10 feet of the array as required by 690.12.
Select a location where the Shut Off Box will be easily accessible in an emergency. Type 3R units are rain
resistant and can be mounted outdoors. All unused holes should be blocked using RTV sealant or something
similar in order to keep rain and insects out of the enclosure. Care must be taken to insure that no water will get
on internal parts when mounted less than vertical. Type 4X units are submersible to two meters in any
orientation, so it will certainly be watertight above sea level. The shut Off Box is required to disconnect inverters
when their input capacitors won't drain within 10 seconds as required by 690.12. Be sure to comply with all local
and national code requirements including National Electrical Code, ANSI/NFPA 70. Use Class 1 wiring methods
for field wiring connections to terminals of a Class 2 circuit. Use only 14-1/0 gauge AWM wire. Select the wire
gauge used based on the protection provided by the circuit breakers/fuses. Shut Off Boxes should be mounted
with #10 or larger stainless steel hardware.
There are various wiring diagrams and system examples available at www.midnitesolar.com click on Documents
at the top of the page for links to wiring diagrams in PDF as well as links to AutoCad wiring diagrams and even
solid models aimed at aiding the system installer and designer. As such we request that they not be used for any
other purpose.
Caution! Do not disconnect any cables under load. Remove power prior to connecting or disconnecting any
cable connections. If necessary, cover the solar panels with opaque material to remove power.
Extremely bad things Will happen if connections are opened under load.
Remove top cover prior to removing
the deadfront on Type 3R units.