This should be considered a "feeder" improvement project; one in which is necessary to accomplish other projects. In this case, I plan on installing Radar and other electronics that have a significant power requirement. A branch circuit to power these devices is in order.
The first task is to assess the power requriements, as well as the existing circuits to the helm. I have determined that there is an existing 10AWG circuit to the helm, but this will not be sufficient for my needs - so I will be installing a 8AWG branch circuit. Follow the link below for a primer on determining DC power requirements in a high-power envionment:
I will be wiring the branch circuit from the main DC distribution panel to the helm area. The first order of business is to punch a hole in the electrical chassis with a "Greenlee Punch". If not obvous, you should turn off the main DC breaker before accomplishing this task.
The DC branch circuit consists of a marine grade duplex 8AWG cable, approx 18ft long. It connects to a 15Amp DC breaker in the main distribution panel. This panel is fed from the batteries, so it is the preferred location to pick up a high current source. At the helm side, there is a 6 circuit distribution panel with fuses for each device. In addition, to ensure a satisfactory signal ground for the radios, an additional 8AWG line is connected from the boat's main DC bonding ground to the helm.
The electrical panel is also actually behind this kick panel. I installed an 8in dia deck plate in front of the fuses so that I could access them without having to remove the kick panel.
After the kick panel is installed, the deck plate cover is screwed on, resulting in a rather protected electrical wiring panel. The kick panel is actually one side of the storage bin at the helm. We typically store our life-jackets in this area. With straps and buckles flying around, you do not want to risk the chance of shorting anything out from them.
If possible, look for a unused spare slot for the new circuit. You should not double up on an existing breaker, but rather install a dedicated breaker for this purpose. Only after all of the wiring is completed should the breaker be installed at the main panel. At this point, the panel face frame may be reinstalled.
The last step is to tie a distribution block at the helm back to the boat's DC system bonding grid. This is often required for proper - or better operation of the radio antennas.
