is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

[FishHunter007]

I am in the process of modifying my 1972 14' boat and am getting close to the electrical stage. I just wanna make sure I know what I am doing.

I am using a fuse block with 4 fuses that previously had 14 and 16 gauge wires running to and from it. The fuses are different, there is a 30, 25, and (2) 20's. I am planning on wiring front/back light, cigarette lighter, trolling motor, and fish finder. I am planning on running the trolling 30amp, fish finder 25, and the other 2 20 amp. The trolling motor would be 10 gauge, the rest 14 gauge wire. Does this sound ok?

Also, is it ok to run 10 gauge from the battery to the fuse block and then continue with the gauges I posted? I also attached a simple wire diagram I am planning to go with (there is a bilge pump in that, but I am waiting on that for now). I am new at this and any help is much appreciated. Thank you.

 

[dingbat]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

You have the possibility of a 90 amp load on that line the way the block is fused. Personally, I'd run 6 gauge.

 

[Texasmark]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

12v circuits need a lot of amps to deliver any power.

American Wire Gauge specifies amperage load for line drops for various sized wires and currents therein.

Problem with that is that they are "really" based upon power line voltages; like 120 or 240vac. Power line voltages are 10x battery voltages found in most smaller boats. Therefore, you have to be really careful attempting to apply NEC wire size/amperage data to small scale marine applications.

For me, a good rule of thumb, is to increase the cross sectional area of the wire by 10x for 12v applications as compared to what the NEC says......but everything is subjective and a lot of power line data is based upon 100-200 foot runs. Your boat may only be a 10' run which means that you can multiply your current by 10 vs the 10 you lost as mentioned previously,,,,,,,,simple isn't it......I'm going to bed.

Mark

 

[stylesabu]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

ok #10 wire can handle 30 amps continusly. your trolling motor will draw almost this much at high speed.Fuse your feed at battery 30 amps, as close to battery as posible. then run another line/wire to trolling motor fuse it again. lighter will need 15 amps, fishfinder about 5, running light 5 amps, bilge 10 amps, livewell 10 amps.if everything is running at once you may pop fuses. but unless you do an amp draw on each load you won't "really " know how much each drvice draws. another rule of thumb check each wire while in use, if hot toi the touch guage of wire is to small for load,it is aways posible that load is drawing to many amps.. All electrical devices will give amp draw on the spec sheet, if don't have spec sheet go to website and look up part/model number

 

[bruceb58]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

The trolling motor should have its own dedciated circuit through a circuit breaker at the battery. No need for it to go through the fusebox.

 

[FishHunter007]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

k thanks for all the input. Would I want to have a 30amp circuit breaker then?

 

[FishHunter007]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

also, I bought my switches before I did my research (bad idea I know). and I guess I bought 10amp switches. Will these work? or just for certain things? Thanks for your help.

 

[Silvertip]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

There is a sticky at the top of the forum showing generic boat wiring. Things I see wrong with your plan are:

1) We have no idea how big your trolling motor is. Roughly, current draw for them is 30#/35 amps, 40#/45 amps, 50-55#50 amps. With that in mind, you DO NOT want to put a switch in the troller circuit. You need a 40 - 50 amp breaker at a "dedicated" troller battery and #6 gauge wire directly from the battery to the troller. It does NOT pass through the fuse panel.

2) Gauges should be powered from the "A" (accessory) terminal on the engine ignition switch.

3) The fish finder has an ON/OFF switch - why do you need another one.

4) Except for the accessory outlet, 16 gauge wire is great plenty for anything on the boat light lights, radio, etc., that are not high current draw items.

 

[jhebert]

Re: is 10 gauge wire ok to run to a fuse block with 20/30 amp fuses?

In designing a 12-volt power distribution system, you need to select the conductor size based on both the current carrying capacity and the allowable voltage drop. In most cases the calculation of allowable voltage drop will cause the wire size to be increased compared to the wire size calculated if only the current were considered.