Electrical System

As I write this account, I have few suitable pictures to show - these will be taken and posted as soon as I get a chance.

My Morgan came with a few DC and AC circuits - plus the wiring did not meet current code - so I ripped it all out and rewired the boat from bow to stern, there is not an original piece of wire on the boat.

A wiring diagram is available in PDF format for my Morgan. This is not a totally complete diagram - I need to check a few things next trip to the boat to finish it up!

As noted in the Charging System section - it is now recommended that a common positive distribution point (PD) and a common negative distribution point (ND) be used to run all wiring from, keeping the number of wires that go to the battery to a minimum. Major wires connected to the ND include a ground wire to the main mast, fuel tank, engine, engine alternator, Genie alternator, wind generator, windlass, and distribution panel. The PD contains connections to the engine alternator, Genie alternator, wind generator, and windlass.

DC wiring on a boat today should be stranded, tinned copper wire. Rather than the typical white and black, it is now recommended that red and yellow be used for DC wiring. This keeps the chances of connecting the ground lead of a DC circuit to the hot side of an AC circuit - which is indicated by a black wire. All my wiring was Anchor wire purchased through West Marine.

From the ND a wire that runs to the distribution box. I replaced the original wooden Morgan box with a larger plastic box which has a clear hinged front. A unique terminal strip was created by placing a base rail across the width of the box near the top and near the bottom, and then snapping on the number of terminal strips I needed. Plus 12 volts comes to each terminal through a breaker in the breaker panel. The corresponding device is wired to the terminal strip. Minus 12 volts is tied to a bus bar inside of the distribution box and the ground wire for each device is connected to this bar. Each terminal strip is labeled as to the device connected to it.

The AC circuitry is similar. Power is feed to each double breaker in the breaker panel - it is recommended that an AC breaker disconnect both the hot and neutral wires on a boat - thus the double breaker. The output of each breaker goes to one side of a terminal strip in the distribution panel. The device connects to the other side of the terminal strip. The ground wire from the device is attached to a grounding bar in the distribution panel. This bar is connected to the neutral wire of each terminal strip and to the ND of the boat.

An inverter converts 12V DC to 120V AC at 60 Hz to run standard household devices. I wired my ProSine 1800 inverter such that there is no AC power to it, and the AC out of the inverter goes to one side of the normally closed (NC) contacts of a DPDT relay. The other side of the contacts, normally open (NO) is wired to the shore AC - and to the coil of the relay. With shore power present, the relay is energized and AC power through the NO contacts feeds power to the AC breakers. Should the shore power be dropped, the relay releases and the NC contacts engage and feed 120V AC to the AC breakers from the ProSine inverter. The inverter is not capable of providing enough current to run all the AC loads, so care must be exhibited turn off major loads not needed when motoring or running from batteries. The ProSine 1800 can supply up to 1800 watts, about 15A at 120V AC. This is large enough to run the 1000 watt hot water heater or the 7000 btu heat pump in the aft cabin - but neither for long. The Genie150 Generator is capable os supplying enough current to run the ProSine 1800 at maximum output.

One other feature on the AC shore power input is a pair of Galvanic Isolators. These are recommended in order to prevent any stray electrical paths to be set up due to incorrect wiring at a dock or nearby boat. Galvanic reactions can dissolve metal in contact with the hull - including through hulls. A disintegrated thru hull can allow the boat to sink.

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