Chapter 10
Electrical
General
(a)
The use of electrical grease and other anti-corrosion products is strongly discouraged.
(b)
Do not attempt to make wiring connections or alterations with power supplied to system.
(c)
Always disconnect the power supply by removing the fuse or turning off the breaker before
working on electrical components and/or connections.
10:1 Power supply
The power supply to the electronic controller must be given particular attention to prevent nuisance
problems and compressor non-operation, shutdown, or failure. All electrical connections should be
either soldered or made with good quality crimpers and crimp connectors of the correct size and type.
All switches, breakers, and connections must be in good condition and be designed and constructed for
marine use. It is suggested that during the initial start-up the supply voltage be monitored at the
terminals on the controller before, during, and after the compressor starts, to ensure that the voltage
stays steady and does not fall appreciably. This test should be conducted with as many other DC loads
turned on as is practical.
10:2 Wire size
Never use less than 10-gauge wire.
If the sum of positive and negative cable lengths exceeds 30 feet,
consult ABYC tables for appropriate wire size for 3% volt drop.
10:3 Overload protection
Use either a breaker or fast-blow fuse with
15-amp rating
for a 12v supply, or 7.5 amp for 24v.
10:4 Connections, Power
Connect the power supply to the controller on the top two terminals using slip-on connectors and wire
size no greater than 10 AWG, observing the correct polarity. If wire of greater than 10 AWG is used
for the power supply, this must terminate remote from the controller and down-size to no greater than
10 AWG for the final connection to the controller. Reversing the polarity at the terminals will prevent
the compressor from running, but should not cause immediate harm to the controller if the correct fuse
or breaker is installed.
10:5 Connections, Mechanical Thermostat
Connect the two slip-on connectors from the thermostat to the “C” and “T” terminals on the Danfoss
(Secop) controller, or the
Merlin II
mini Smart Speed Controller if installed. Color and polarity are not
important.
On some models, a Speed Board is mounted on the lower terminals of the controller, and the “C” and
“T” terminals are replicated on this board. The speed must be set to a speed specified for the system
and size of evaporator, as outlined below, and the voltage switch set accordingly to ensure the correct
low voltage threshold setting.
NOTE: The Speed Board cannot be used if a
Merlin II
is installed. If your compressor unit was supplied
with a Speed Board already installed, this must be removed if you are using a
Merlin II.
See separate instructions for systems using the Coastal MK3 digital thermostat.
