Where is the best place to pull a positve wire for accessories like a stereo or GPS

[Spence340]

Is there a good place to hook up stuff under the dash besides the ignition switch? I was told to get a small block that has terminals on it that hooks up to the battery but I would like to avoid running a live wire all through the boat for something like a GPS or fish finder.

 

[merc120_81]

home run to the battery a dececnt gauge hot and ground and run it to a small fuse block/terminal block. remember the negitive has to be able to carry the load too. and fuse everything as close to the power source as you can.

 

[gm280]

Any place under the dash that could possibly carry enough current to run a stereo and fish finder has to come from the battery to start with. Adding another run is the better way to do what you want. But make sure to fuse at the battery for starters and then even as you break out each run to the individual places. That way you are covered and won't burn the boat down if something shorts out any place on the hull. JMHO

 

[Spence340]

I guess I will run a new line to the battery but I hate having all the extra wires everywhere. I'm surprised the boat builders (this is on a 86 sea ray 21MC) didn't leave some extra capacity behind the dash where all the wires are for future stuff that would be added later. What gauge wire should I use and is there any color preference when wiring add on stuff so future owners will have a better idea what the wire is for?

 

[Alumarine]

#14 should be ample for the GPS.
Can't help with the stereo. Depends on how much power it puts out.

 

[gm280]

Spence340, Any place under the dash, helm, that you can tap on to that will not over current the capability will work. Add up the current for everything on the line you want to add on to and see if the fuse and wire is capable of carrying the exact current demand. If so you can add on to an existing circuit.

Example; you have a circuit that is fused at 10 amps and you added up the total current of all the things attached to that 10 amp fused circuit and it only comes up to about 6 amps. If your fish finder and stereo don't draw more that 3 amps total (I like a little lead room), you could add on to that circuit. Then the total, with everything running at the exact same tie would be 9 amps. So you are not over drawing that circuit. I hope that explains it better. And please don't just change the fuse to a high current one. If the wires supporting that 10 amp circuit can't handle a larger fuse, you could heat up the wire and start a fire. On the water, you can't run away from a fire. JMHO

 

[dingbat]

Spence340, Any place under the dash, helm, that you can tap on to that will not over current the capability will work. Add up the current for everything on the line you want to add on to and see if the fuse and wire is capable of carrying the exact current demand. If so you can add on to an existing circuit.

Gang fusing sensitive and essential electronics is never a good idea.

Gang fusing is acceptable for lighting, maybe pumps, but never electronics. Introduces far too many scenarios with undesirable outcomes.

Every boat I've owned had a fuse panel under the dash. If not, install one. If you have one, but not enough fuses, install a larger one.

 

[gm280]

Gang fusing sensitive and essential electronics is never a good idea.

Gang fusing is acceptable for lighting, maybe pumps, but never electronics. Introduces far too many scenarios with undesirable outcomes.

Every boat I've owned had a fuse panel under the dash. If not, install one. If you have one, but not enough fuses, install a larger one.

dingbat, I honestly understand what you are saying.

However, electrons have no idea if they are coming from a fused circuit with other things going on, or straight from the battery. Everything has to have a positive and negative line to operate properly. So regardless where you get that power from, your add on will work IF you are not over loading the wires and/or fuse for your add on.

Yes, it is always nice to have break out fuses for everything on a separate line, but power is power, and if you are not exceeding the limitations of the circuit, it will work and work properly.

Your house is wired using ganged circuits but not to exceed the circuit breaker for each line. You have multiple outlets and lights ganged on each circuit. And if you don't exceed that circuit's current requirements, everything works happy together. JMHO

 

[bruceb58]

Every boat I've owned had a fuse panel under the dash. If not, install one. If you have one, but not enough fuses, install a larger one.

This is exactly the correct way of doing it. If the current fuse box doesn't have enough fuses, you can add another panel next to the original one.

 

[Glaspar_Fan]

The absolute basics:
1) Power is ALWAYS two wires, one hot, one ground.
2) Wire size is based on max current and total run length ROUND TRIP (positive terminal to device and back to the ground terminal.)
3) The primary cause of electrical problems is bad terminal connections.

To determine wire size, add up the current for all the devices the wire will supply, measure how long the ROUND TRIP is, then go to a chart (Google is your friend) that shows voltage drop by current, wire size and run length. You decide what voltage drop is acceptable. I personally shoot for less than 5% (.6V) but most 12V devices for cars and boats spec +- 10% (1.2V) as OK. Don't ever just add another hot wire, it's only half the solution. Always add a new ground wire when you add a hot wire.

I have a 1988 Searay SR268(?) that I picked up about 5 years ago. I was surprised that all the power under the dash was coming through 10ga power/ground. It's about a 25 foot run to the battery (50 ft round trip.) There were dash fuses for the original standard items (pumps, lights, etc.) but all the owner-added stuff was ganged to a little 4 fuse strip that was rusting. The previous owner had starter problems he couldn't fix even by replacing the starter. As soon as he demonstrated the problem I knew what the solution was and he was looking at the wrong end of the boat. It was simply bad connections under the dash which I cleaned up and/or replaced before the boat ever got in the water.

My wiring now includes a 12 fuse auxiliary buss fed by 8ga power/ground in addition to the OEM 10ga. And I've never had an electrical issue on the water.

One last thing, don't buy your boat electrical stuff at a big box hardware place. It just isn't sufficient for marine use. As expensive as the marine electrical hardware is, it's the cheapest way of assuring reliability on the water.

 

[bruceb58]

For wire and connectors go here:
https://www.genuinedealz.com/

 

[dingbat]

Yes, it is always nice to have break out fuses for everything on a separate line, but power is power, and if you are not exceeding the limitations of the circuit, it will work and work properly.

I've been in electronics manufacturing and service far too long to agree with that philosophy.

Power surges, power switching, voltage drops, ground faults, etc. can all play havoc on electronics.

I just sent a quote to a guy for almost $75K in equipment and services because he decided to use the common supply ground instead of the isolated instrument ground specified in the documentation. A ground fault smoked a $4K power amp which in turn smoked a $2.5K power supply and a $45K x-ray source. This is in addition to the $30-40K in down time so far....Needless to say, he's not a happy camper.

You can never to be too careful when it comes to powering electronics. Especially when it comes to boats that inherently end up with bad or dirty power.

 

[Grub54891]

I have to agree with dingbat, we are seeing more and more high dollar electronics on boats from small runabouts, moving up to large cruisers, Good clean power is a must have! On every install we do, we find out the amps, totaled up for a run, then up that wire a notch, just to be safe. Even then, an owner will decide to add something else next year so it's best to have the line ready for stuff, I know I'd hate redoing a run that was just put in, It's not easy sometimes. Now on a small boat, just basic fishfinder and radio with no amps and junk, you can get by with a simple run, you might get interference from using that run combined with something else, you might not......Do it right or do it again. My 2 cents.

 

[Spence340]

Wow, A lot to digest here, first thing I need to do is to find out if and where the fuse panel is. This is on my 1986 Sea Ray 21MC so if most all boats have a fuse panel I would think a Sea Ray does unless of course it is too old to have one.

 

[LuCroix]

Even my 1967 OMC Sportsman has a fuse panel