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(Original article by Phil Sensibaugh, edited by Bill Pickl)
There has always been a lack of consensus involved with determining what size of wire to use when wiring your ship. Some builders feel that large diameter wire is better while others use the smallest diameter wire possible to carry the load current. Realistically, since the speed of our ships is limited by the rules there is no need to use large wires to allow greater current flow to the electric motor(s). Based on my experience the maximum current needed to propel the largest of our ships to speed is about 2 to 3 amperes. Of course, using less efficient motors or an inefficient (high friction) drive system could increase the load current somewhat.
The U.S. military is very conservative when rating the current carrying capacity of wire. Military Standard (these are warships after all) Mil-W-16878E entitled, "Wire, Electrical, Insulated, General Specification for", dated 10 Aug 1998 defines the convention used to determine the current carrying capacity of wire. Before going into this calculation I must first explain that current flow is near the outer surface of the wire, not the center. This means the surface area of the wire conductor is the primary factor governing current flow. Figure xx makes it quite simple to see that a stranded wire has a lot more surface area than does a solid wire of the same diameter and as such, will carry a greater current.
The Table lists the current capacity of a large range of wire gauges. Typically our ships only draw 2 to 3 amps per system and the table above on average ship current draws can be used to size the wiring for your ship. Note, if you branch out from your main power bus you can most likely drop the wire size to match the demand for that subsystem. For example a battleship would need at least 18 gauge wire from the battery to the power bus then the motor and speed control subsystem would need at least 20 gauge wire. The pump and radio system could get by with as little as 24 gauge wire. Of course you can use larger gauge wire with no ill effect, but doing so will provide virtually no benefit given the relatively short runs of wire in our ships. It will however, increase the size, bulk and weight of the wiring and take up valuable space within the ship.
Since I am discussing wires, it is also a good time to address wire connections. The "crimp" type wire connectors used in care are not well suited for rc combat warships. One problem is that often this type of connector is made of tin or steel, whereas the wire is typically made of copper. These differing types of metals making contact with current flowing through the connection causes an effect known as electrolysis, which causes the connection to corrode quite quickly. This corrosion increases friction causing a voltage drop across the connection and sometimes will totally interrupt current flow. One method to lesson this problem is the usage of anti-corrosion paste before crimping the connection. However, I prefer to solder all wire connections to totally eliminate the potential for a problem.
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