I'm doing a decent refit of the boat (repowered, new electronics, etc). I was original planning on just replacing the old glass style fuse panel to blade fuses and cut out all the old unused wire from various previous owners, but now that I'm in the console and running harness for newer motor, I figure I may want to replace main feed too (2000 model year boat). I don't have a lot to power - two 9" screens, VHF, radio (no amp), LED spreader lights, all normal, fresh and raw water pumps, and finally safety equip. I can't really judge what size the factory one is.....not terribly large...and may not need replacement, but almost seems silly not too as this point in the project. Any recommendations? Looking at a chart and 4 AWG can support 100amps at a 15-20' run, so should be plenty (admittedly have not tallied everything up yet)
Rewiring 263 Chase - what gauge?
- Thread starter Drew61199
- Start date
4 gauge sounds a pretty large to me. More on that later.
Before you jump into the work, you probably want to do a reasonable estimate of actual loads. You can not add up the recommended fuse sizes for each component to get the running load. In every case, the running load will be lower than the recommended fuse. Spreader lights can draw a lot of current and the actual draw depends to a large degree on the type. LED lights generally draw a lot less current all else being equal.
It is important to remember that the ground side conductors have to be sized correctly. Just changing the how (+12v) conductor does not necessarily increase the current capacity of the accessory fuse block.
The run length for current capacity sizing is the total distance bot to the panel from the battery switch plus the length of the run (ground conductor) from the fuse block back to the battery area.
You have an existing accessory breaker near the batteries, It may be 30 amp or larger but whatever it is, if original, was a factor in determining the conductor gauge.
All components should be matched to each other. For example, the fuse block will have a maximum current capacity. Upping the wire gauge does not mean that the fuse block can handle more current. For sizing of breakers, you should design the steady state current draw to not exceed about 80% of the breaker size. Short term current draws may draw more that that but that's ok. Indictive loads and mechanical loads such as pumps will have a higher inrush (startup) current draw than the usual running current.
Non electronic loads should be designed for no more that a 10% voltage drop but electronic/voltage sensitive loads use a 3% voltage drop. If your voltage drop is too high, it can cause electronic devices to alarm, restart, or shut down.
I do not know your level of DC electrical experience and my apologies if none of this is new info to you.
If you want to read a decent basic primer on marine wiring, try this
newwiremarine.com
Before you jump into the work, you probably want to do a reasonable estimate of actual loads. You can not add up the recommended fuse sizes for each component to get the running load. In every case, the running load will be lower than the recommended fuse. Spreader lights can draw a lot of current and the actual draw depends to a large degree on the type. LED lights generally draw a lot less current all else being equal.
It is important to remember that the ground side conductors have to be sized correctly. Just changing the how (+12v) conductor does not necessarily increase the current capacity of the accessory fuse block.
The run length for current capacity sizing is the total distance bot to the panel from the battery switch plus the length of the run (ground conductor) from the fuse block back to the battery area.
You have an existing accessory breaker near the batteries, It may be 30 amp or larger but whatever it is, if original, was a factor in determining the conductor gauge.
All components should be matched to each other. For example, the fuse block will have a maximum current capacity. Upping the wire gauge does not mean that the fuse block can handle more current. For sizing of breakers, you should design the steady state current draw to not exceed about 80% of the breaker size. Short term current draws may draw more that that but that's ok. Indictive loads and mechanical loads such as pumps will have a higher inrush (startup) current draw than the usual running current.
Non electronic loads should be designed for no more that a 10% voltage drop but electronic/voltage sensitive loads use a 3% voltage drop. If your voltage drop is too high, it can cause electronic devices to alarm, restart, or shut down.
I do not know your level of DC electrical experience and my apologies if none of this is new info to you.
If you want to read a decent basic primer on marine wiring, try this
Wiring A Boat
Beginners guide: The basics of boat wiring. Wiring schematics, pictures, best practices and tips to get your boat's electrical systems in shape.
newwiremarine.com
If you want to replace the stock wiring and wondering what gage all that info is in the user manual available on grady's website.
Although there is info on color and wire size, the routing info is somewhat generic. It is not an engineering drawing of the wiring harnesses and doesn't tell you where conductors split off, how long the run is or if there is a splice for shared grounds or certain lights