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Electrical Planning: Wiring Schedule

posted Apr 22, 2011, 12:21 PM by Christopher Hubbell
Having nearly completed the structural work, inhibited only by temperatures, I am now moving on to the electrical, plumbing, and mechanical systems.  The electrical system seems to be the one which is most demanding of my thoughts at the moment.  I have discovered that most of the wires in the boat are not correct in one way or another.  I believe I have located one or two which are terminated properly, and we wont' even discuss the rat's nest that sits above my engine bay.  Time for some radical refitting.

The first thing I did was to rough out a list of every major electrical component I have on the boat, and any items which I intend to realistically add to the boat within a reasonable time frame.  I then started messing around with options for combining these devices into circuits based on load, locations, or use.

The next step was to grab some images from Google and start putting these into a diagram which includes a DC panel, and each device.  The devices were then "wired" with lines on the diagram to show circuit paths.  After ensuring I hadn't forgot anything, power consumption per device was recorded.  This was mostly done by downloading user guides or specification sheets from vendor web sites.  In some cases I found a device which was "close enough" to what I have, or perhaps a bit more powerful to be conservative.

The final step involves estimating wire run lengths.  This is critical because ABYC codes require that an appropriate gauge of wire be used with respect to lengths of run and amps of load.  These wire gauges are identified using voltage drop tables.  Since my boat is about a 30 minute drive from my home, and I can't be there all the time, I needed an alternative model to plan these wire runs.  I ended up creating a roughly dimensioned drawing that would get me "close enough" to pick wire gauges.  I have posted a PDF version of the Rough Internal Dimensions Drawing on this site for reference.

The final drawing tells me the length of each cable run, how many amps the circuit may potentially carry, how it is fed and grounded, and the size of fuses.  The drawing is evolving frequently, but I'll try to keep the on-line version relatively current.  I have also uploaded the Ravat Electrical Plan file as a PDF document for reference should anyone else feel like refitting a CS27 and find it useful.

First on the agenda is getting the AC charging system installed, and the batteries reinstalled.  This of course is awaiting weather warm enough to allow me to paint the aft cabin bulkheads and cockpit lockers.  Hopefully the weather will soon cooperate and release its tenacious grip on winter.