trying to figure my total amperage

[bob johnson]

I am wiring my new boat...I bought it as a tiller version, but am adding a center console i bought at the same time from the factory. I am going to buy a breaker panel. the center console came with three switches fused through their fuse panel....Ill use those three for running lights an anchor light and interior cabin lights...so they wont be on my breaker..

everything else I am going to run will go through a 6 postion waterproof breaker.

they sell them in 45 total amps and 100 total amps...

I will run two seperate wired bilge pumps( on seperate circuits)
I will run a depth finder
I will run a spot light
I will run a radio
I will run a circuit for a future live well


my question is how much should I set for the trip on each circuit.. the bilges I already have and were used

1000 gph each Rules

also I am running a power source for a hydraulic powered jack plate

and am running a few guages

like a water temp
a water pressure
a fuel pressure guage
a tach
an amp gage

should i supply each power source to my guages through the breaker ???

would the spot light and the bilges be the largest amp draws??

would a 20 am be sufficient for them??

I figure the radio wont need much

nor will the fish finder

the spot will be via a cigarette lighter type power recepticle ..so other things might get plugged in once in a while

I mlike the breaker so i dont have to crawl under the console and replace fuses

I figure if the breaker goes twice in short order...just leave it off...till I find the source..but otherwise it would be quick to bring it back up!!

thanks

sorry of the questions are a slight mundane....

thanks

bob

 

[This_lil_fishy]

Re: trying to figure my total amperage

Each item should have current draw ratings (excluding the lights). Check them, and add them up. That's the easiest way. We couldn't possibly guess for you. For your lights: current(I)=power/voltage. So each 50watt bulb would draw about 4amps on a 12v circuit.

Ian

 

[Joseph10]

Re: trying to figure my total amperage

It is OK to use a main breaker for the entire circuit, but make sure to only gang enough stuff on a single circuit that the gauge wire you are using can handle. Also, make sure that each sub-circuit has a separate smaller fuse, that is selected based on the wire current handling capabilities for the wire size used in that subcircuit.

Make sure to leave yourself some margin between the fuse size and wire gauge (i.e. make sure the fuse blows at some amperage slightly below what the wire can handle). Failure to use individual fused subcircuits is dangerous.

 

[Chris1956]

Re: trying to figure my total amperage

Bob, The gauges use little current, as does a digital ff. If the radio is VHF it uses little current as well. Stereos can use from little to a lot of current, depending on type.

Put the jackplate on a 30A dedicated circuit. Put all the low current items(except gauges) on a single 10A circuit, with a single master cut off switch. The gauges are powered by the ign switch. I hook the gauge lights up to the ign switch as well.

Lights can share a circuit and switch. Figure 3A each light. Livewell on its own circuit.

 

[Joseph10]

Re: trying to figure my total amperage

Make sure to be reasonable when grouping loads together. For instance, it would not be good to put a low amperage item on a circuit with a large amperage item (say a 1amp item with a 20amp item). A resistive short in the 1amp item with a total current draw of 19amps (assuming the 20 amp item is off) may generate enough heat to cause a fire etc. It would be best to group all the low amperage items together and fuse the higher amperage items individually with separate fuses.