Switch Panel Question

[WesS]

I am wiring up my 14' wooden boat I built. I have read about the grounding issue and plan on sending all negative to the battery. It is a 12V so I should be good? I have bought a 6 switch panel for running, anchor, bilge, floor lights, head lights, and fishfinder. The panel has a breaker switch button for each switch, do I still need a fuse panel? Do I still need to fuse from the battery? Do I still need to fuse to the fishfinder? If so is it best to fuse on positive or negative? THanks.

[CDK]

No, no and no!
If the switch panel has circuit breakers you have everything you need.

[WesS]

So no fuse to panel from battery or one to fishfinder?

[jonr]

Each wire should have a fuse somewhere in the path that will blow before the wire overheats and starts a fire - ie, the wire size and the fuse/breaker size are related. This rule includes the supply wire from the battery.

It would be a mistake to wire a fishfinder with small guage power wire to a large breaker. The fishfinder could short out internally and the supply wire could start a fire without the breaker blowing.

Fuses/breakers near the source are better than further downstream - something could cut into the wire.

[WesS]

So, even though the panel has a breaker I need fuses?

[jonr]

Not necessarily - if I can point to any wire and you can point to a fuse or breaker that will blow before it exceeds its safe current, you are fine.

On the other hand, if you want to connect a fishfinder with 20 gauge wire to a 20 amp breaker, yes, safer to add a fuse.

[WesS]

thanks

[CDK]

Originally Posted by WesS

So no fuse to panel from battery or one to fishfinder?

You asked three questions, I gave three answers.

[kim s]

Ahh----finalysomething on this wholeforum I know something about

Wess, this I know will seem a daft question---when you say the panel has 6 breakers---do you mean straight switches (on/off) or are they trip switches. ----do they have an amp rating.
This might be a case of my mis-understanding the American term.
There are 2 different sorts of panels. one that has a switch AND a fuse and some that appear to just have a switch--these are the fuses as well.
My only thing to advise is to make sure (as johnr)stated, every wire supplying a piece of kit, MUST have a fuse somewhere. People think the fuse is to protect the kit at the end-----ITS NOT. its to protect the wire supplying the kit. If the wire chafes against a bulkead and shorts out, you want the fuse to break before the cable gets hot enough too catch fire
so a cable rated at 16amps does not want a 20amp fuse. if the kit fails and shorts out, the cable melts and causes damage before the fuse blow

One that a lot of people miss out, is the wire that comes from the Battery to the switch panel.(remember the fuse is to protect the wire).

There are many good books on boat wiring.
Other tip ----use multistrand cable -not solid core. it breaks fairly quickly due to work hardening. the best cable is tinned throught its length as it does not corrode.

Kim

[WesS]

thanks kim. Th switch panel has reset buttons/breaker buttons for lack of a better term and also the on/off switches. Does that help?

[WesS]

First- I did thank him on 2/09. 2nd- thank you

[jonr]

Other things: use tinned wires, no wire nuts.

Here is a calculator for wire size:

http://beta.circuitwizard.bluesea.com/

[Guest62110524]

Originally Posted by WesS

First- I did thank him on 2/09. 2nd- thank you

my sincere apologys

[kim s]

Originally Posted by WesS

thanks kim. Th switch panel has reset buttons/breaker buttons for lack of a better term and also the on/off switches. Does that help?

That sounds lie they are breakers (fuses/trips) . you should find some where on them the rating . ie 5A , 10A.
If thats the case, then just connect the wires to your radio etc. You need to put things that use a large amount of electriity on the higher rated fuses. things like nav lights ,or bilge pumps, and things like fish finders, radios , gps on the lower rated ones. Its best to put you VHF/DSC on its own switch, dont connect other things to that circuit so you keep interferace down. also use the largest cable possible for the rating of the breaker, so you dont get a voltage drop, which will effect your output when you transmit for help , cos your boats on fire cos some idiot from UK advised you how to do the electrics
I strongly advise you purchase a book on it ,as a picture tells a 1000 words etc, but it sounds like you have a good start to your project.
good luck
may all your terminals be nice and tight

Kim

[goboatingnow]

in-line fuses have no place on a boat in my opnion. Try hunting behind panels to find that forgotten fuse in an emergency.

Size your panel breakers to suit, anyway electronics fail before the fuse blows anyway.