# Wiring Basics - busbars and terminal blocks



## cstallings

Ok, so I hate to ask this since so much information is already on tinboats.net, but I guess the light bulb has not come on yet. I have an old Lowe 1448 boat that I have had for 10 years or more. Over the years I have gutted the inside with the exception of the back bench seat. Last year I built a nice large front deck on it and just carpeting the entire boat a few weeks back. My son is 4 and wants to go fishing more, so I had to make it suitable for him. Looks extremely nice now, but I need to wire it up correctly. I'm good with wood and metal, but not so much with wires. The attached set up is approximately what I want. I may add some small things, but this is roughly it. I've been running two batteries...one in the front and one in the back. But I only want to run one going forward (I think). I think the extra battery is just added weight for me. I want to run everything from a switch panel…except for the TM I think.

Can someone enlighten me on the following things:
1. What area busbars used for
2. What are terminal blocks used for
3. I believe I need to run my power wires for my accessories on the opposite side as my transducer cable for my FF....correct?

Any and all comments are welcome. Thanks!


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## captdan

Think of busbars and terminal blocks simply as an extension of the battery. They help to eliminate the stack of wires that would be onto the battery. For example: If you have a bunch of accessories that are running to a switch panel. each of your positives from your accessory would be attached to a switch, and a positive running to the battery. Instead of having a positive for each of your accessories, you could run 1 positive from the battery to a busbar where each wire is getting dc power. You may or may not want to give some items power at all times, like a radio/cd player that needs a constant supply of power.... 

I use terminal blocks most of the time only for a ground. I can stack all the grounds for my access and have a clean battery compartment. 

Id advise keeping 2 batteries. Use one for your trolling motor..... one for your accessories. I use my trolling motor a lot, ans have a dedicated group 27dc for it. I use a small lawn mower batt for my accessories as they really dont draw all that much juice/I dont run them all that often...


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## cstallings

Thanks. So busbars are for positives and Terminal blocks are for grounds?


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## RivRunR

I agree with captdan, I'd keep that second battery just for the TM, especially since you've already got it.

Wire the TM positive to a 50 or 60 Amp circuit breaker (depending on mfg recommendation) with 6AWG, or even 8AWG since it's a short run, then from that breaker over to your front battery positive. The breaker should be 7" or less from the battery. Negative on the TM can go straight to the battery with the same gauge wire as you used for positive. If you need a TM plug, just put that in line between the breaker and the TM.

For your accessories, from the rear battery positive run a lead to a smaller circuit breaker, I'd guess 15A or 20A depending on your total amp load, then to a fuse panel. You can use the same heavier gauge wire that you used on the TM for these battery-to-breaker, and breaker-to-fuse-panel runs. Run the fish finder and 12V plug directly to the fuse panel since they don't need to be on switches. For your switched accessories (bilge, navs, floor lights, etc) run the accessory positive lead to a switch, then from the switch to the fuse panel. For the negative side, get something like this buss bar and run a 6 or 8 AWG lead from your battery neg post to that, and then connect all your accessory negatives to the buss bar.

On a 1448 size boat, and without knowing your exact distances and amp draws, I'm going to _guess_ that 14AWG would be plenty for all your accessories except the 12V plug (and maybe your floor lights), which should probably be 10AWG. You need to go to one of the many online charts to figure out exactly what gauge you need based on your amp load and distance (both pos and neg runs combined). Here's a sample chart.

For switches, you can either get individual switches, or a switch panel. For most of your accessories a simple SPST on/off switch will do it, but for the navs you probably want a DPDT on/off/on switch.

I've probably left things out, but someone will chime in to fill in the gaps.

Hope this helps!


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## cstallings

Thanks a lot for the help. One thing that has really confused me is people seem to use bussbars and terminal blocks interchangeably…is this right? Is there a preferred method? I think I need to find a book…
As far as the smaller circuit breaker…is this like the larger resettable TM circuit breakers? I have a 50 for my TM.

Thanks!


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## RivRunR

No, they aren't exactly the same thing...

A terminal block has a series of paired connections, but each pair is independent from the next pair...a one-in / one-out type of setup.



A buss bar has a single (or double) feed to multiple connections, a one-in / multiple-out setup. So, in the pic below, you have a feed on the ends where the nuts are, that connects to all the terminals where the screws are.



I used the short stop breakers like these from Waytek but that's because I had them on hand, there may be a more marine-specific type out there somewhere.


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## cstallings

So what is the benefit of the terminal block? It doesn't clean up the wires if you have a wire running out for each wire running in?


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## RivRunR

I really have no idea, I don't use them.


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## linehand

They are a place to land wires between control and component. 
Buss is solid and has same potential across entire surface. Terminal strips isolate each pair of landing screws.


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## rusty.hook

If your good with wood, look at my pics of a small side console I had built for my last boat. I mounted the light switch and bilge pump switches on it. I also mounted my GPS and depth/fish finer on top. Later I mounted a terminal block on one side to solve all the wiring issues. I ran a black/negative and a red/positive wire from the front battery to this terminal block, then the GPS and depth finder were wired in to this terminal. No need for long wires from either. 
I ran my lights and bilge pump off the back battery a very short run of wire. 
See drawing and pics of my side console below.


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