The issue is not the size of the breaker on the panel but the draw in amps of the items served by the panel. For example the Blue Seas 8023, their most popular DC panel, which has 8 positions is rated at 100 amps. They recommend that it be treated as a 100 amp load. I have this panel and the wire run is short but I am using 2 awg cable - probably overkill but bigger never hurts with cable sizes. Estimate the draw on the panel if everything is in use to arrive at a max expected load and use that as the number in your wire size calculations. Since you're using leds extensively the load from lights should be low. If you have a battery monitor make sure the charger is off and you can determine the actual draw of each item one by one. If not add them up from the wattage of lights and published amperage of other items. You might find the max load is well below 50 amps. Below is an exerpt from the Blue Seas instructions on sizing panel feed wires. The key part is sizing the feed wires for the panel rating or maximum usage whichever is less.
Living aboard in Victoria Harbour
Last edited by mitiempo; 04-19-2010 at 04:12 AM.