Installing a 12 Volt Fuse Block
A much better idea is to put a fuse block somewhere in the middle of the van. That way you run a single 6 gauge wire from it to the battery and all of your other appliances are run to it. Plus each item is fused when you wire it so you don’t have to fuse each item individually. I bought mine from Amazon.com and it’s made by Blue Sea for boats. It has places for 6 fused items and 6 grounds for their negatives. You can buy it here: Blue Sea Systems Fuse Block – 6 Circuits
I’ve done two posts on very basic 12 volt wiring and I recommend you re-read them if you are new to wiring:
Step 1: You need to put ring connectors on the 6 gauge wire to go to both posts of the battery and to the fuse block. First measure to see how long the wire should be and cut it to that length. Then use your stripping tool to strip about 1/2 an inch of the rubber sheath off both ends of the wire. In the picture above you can see where I’ve marked “teeth.” You put the right sized wire in the teeth and squeeze down on the tool which cuts through the rubber sheath but doesn’t cut the wire underneath. Then pull that little bit of rubber sheath off exposing the wire below. You can buy a cheap all-in-one tool from Walmart for about $4 and it will do the job. I do enough wiring that I spent the money and bought quality Channelock tools. Good tools make any job easier! Channellock Wire Stripper and Cutter and Channellock Crimping Tool with Cutter
Step 2: Put the ring connector (it needs to be 3/8 so it will go over the battery post) over the stripped end of the wire and crimp it. In the picture above you can see that you want to squeeze it totally flat so the bare wire is gripped tightly. After you’ve crimped it tight grab the wire in one hand and the connector in the other and give it a good tug. Don’t be shy really try to pull them apart. If it’s going to fail, you want to find out now rather than later.
Step 3: Connect the red wire to the positive post of the battery and to the positive post of the fuse block and the black wire from the negative post of the battery to the negative post of the fuse block. Then mount the fuse block wherever you want it and you’re done! While all your devices will be fused at this end they really should be fused at the positive post of the battery as well. I didn’t have a fuse holder when I did this project, but I’ll add one as soon as I can. You will want to fuse yours as well. You can use this fuse-holder from Amazon: Blue Sea Systems Fuse 30-80A
and use an 80 amp fuse: Rockford Fosgate 80 Amp Maxi Fuse, 2-Pack
Step 4: Now you need to put your shiny new fuse block to work. We needed more cigarette lighter outlets so the first thing I did was add one I had on hand with dual outlets. It’s a very simple job of stripping and crimping. I used 10 gauge wire because there were two outlets. There is a short red and black wire coming from the outlet so I used a butt connector to add a long wire which would reach up front. On the other end I used a spade connector because so that all I had to do is loosen the screws on the fuse block and slide them under the screws and re-tighten them. Easy Peezy!! I only had black wire on hand so I wrapped the positive wire with red electrical tape so in the future there will be no doubt which is positive.
Step 6: When you’ve screwed in all your items, put the cover on and you are done! We’re taking my Dometic 12 volt compressor fridge to Alaska with us and it’s cigarette lighter plug had failed so I just cut it off and crimped on spade connectors. It’s the other item I have wired in here. You can see I only used 2 of the available 6 circuits. So from now on to add anything all I have to do is strip and connect a spade connector onto the wire coming from the item, loosen the screws on the fuse block, slide the spade connector under neath it and re-tighten the screw. Very easy. The fuse block doesn’t come with blade fuses so you’ll need to buy an assortment and use whatever size your appliance calls for.
Once you’ve mastered the basic art of stripping and crimping wire, minor projects like this won’t be intimidating at all. Honestly, anybody can do it!
Thank you for the ongoing electrical lessons. Of all the systems, this is the one I find most intimidating.
Calvin, electrical can be intimidating! The problem is most websites start at too high a level so you’re lost and never get a foundation. I’m trying to start at the most basic level.
I miss your sunday sermons……………sniff, sniff!
Thanks Elizabeth, they got a very mixed reaction, some loved them, some hated them.
But the big thing was time. I needed to cut back my writing schedule so they pretty much went by the wayside.
I’ll try to do more philosophical/spiritual posts for you!
; ) Thanks, Bob. I’ve been going back and reading your older posts. They are so inspiring to me, as a fellow lover of nature and Taoism, reminding me to surrender, quit needing to control others, quiet my need for recognition from those who will never give it to me…..LOL……definition of insanity, as well as reminder to be present and allow myself to blossom, not just for myself, but for others, as well.
Also, I’ve been searching for the name of someone that you often quoted who was an american naturalist, long beard, early 1900’s…… and can’t for the life of me remember his name. Thought I’d search out his books at the library if you can come think of who i’m talking about. Perhaps, if you have the time or desire, you could put a book list in your store, philosophical and practical.
Thanks again for all that you do and who you are. You are much appreciated by me, esp. as an example of that bud who has allowed himself to bloom. (Hope your petals aren’t getting too tattered yet!) In joy and laughter…..Elizabeth
What a lovely comment Elizabeth! Thank you! It was probably John Muir. He is the one who said “the mountains are calling, and I must go!” I love that quote! To be honest though, I find his writing to be difficult to enjoy, but give them a try.
I’m still blooming!
Awesome breakdown Bob. Have fun on your voyage.
This is more my speed (then the last post… the news these days is just to real). I read and approve this message.
The really nice thing about modern electronics and electrical gadgets is they are very efficient and use less current than the past. Your refrigerator, laptop and inverter may be the biggest load on the system. LED lights are a really big deal for efficiency. Good solar panels, the proper charge controller, a couple of good batteries, this setup and you’re set.
I totally agree jonthebru! having all the power you need in a van has become very simple. It’s not cheap yet, but is geting cheaper all the time.
I bought the fuse box through your link for $36 and I could not find the 6 gauge cable. Where do you find it? If I can’t find it, I will put 4 gauge cable instead. It ‘s big cable, well see it might works. Have nice and safe trip to Alaska.
You can get 6-gauge wire at most hardware/home improvement stores. Some sell it by the foot, others make you buy a big roll. Shop around.
Patrick, Home Depot (and probably everybody else) sells it in rolls by the foot. Just be sure you get STRANDED cable. Solid core is too brittle for auto use. Finding the connectors for 4 or 6 gauge can be hard. Every so often Walmart has them but Napa Auto should have them or be able to get them.
I could have used this fuse block info (particularly the type of fuse block) about 10 months ago when I was building out my van. What I rigged together myself is working adequately, but I have a bunch of inline fuses scattered all over (and don’t remember where some of them are). It’s something I can redo when I make some revisions on the Rolling Steel Tent.
Sorry Al, I’ve been planning this post for along time it just took me till now to actually do it. Maybe when you move into the small Transit Connect, eh?!
Bob, I’m curious as to how well your solar panels will work as you move North. I find solar performance to be lackluster at my latitude above the border and would like to hear about your experience.
Have a great trip!
Ming, this will be my first time with solar in Alaska so I’m not 100% sure. But the sun rises higher in the sky in the summer the further north you go that’s why the days are so very long. I think it should be abundant solar!
yes, of course, much longer hours. I was wondering about the sun angle, since you don’t tilt your panels.
Ming, because the sun is higher in the sky it will hit them almost at 90 degrees with them flat, almost perfect, so no need to tilt. Tilting would actually reduce the sun except for very early and late in the day.
thank you for the clarification!
What would be the cost alternative to just a few or two panels? A small trailer holding ten to twenty panels stored inline with soft packing? Twenty panels @ 285 to 300 watts would definitely add a tremendous amount of power regardless of time of year.
We have a 31′ camper and have always thought about going off the grid and in the barren countryside.
You might be thinking of the naturalist John Muir. He was a truly amazing man and was one of the founders of the Sierra Club. His books are a delight to read.
Hey Bob, thanks for another steller post! Would you describe that little light with the dimmer switch? Warm, or bright white? Can you replace the bulb on it? Will it fit the bayonet style LED bulbs that I already have a few of?
Hi Jeremy, I;m not sure how to describe it. It’s plenty of light to read by even for old eyes and I find it very pleasant. I guess it is warm but I’m not sure. Yes, it is a standard replaceable 12 volt auto bulb. I think it’s a bayonete mount but I’m not sure. It’s back in Flagstaff so I can’t check it.
Like irrigation was for me, electrical can be intimidating. Especially since, given enough of it, it can lead to death. But that is why we have safety rules for electrical. Electrical and electronics were intimidating until I took my diesel and automotive electrical classes in tech school. I’m still by far a rook with it, but getting better.
Douglas, I know what you mean, it’s taken me years to get even a bare basic knowledge of 12 volt and I have a LOT to learn yet.
My gray and black water supply light do not come on in the panel nor does my battery read any voltage but then everything else works does this mean my inverter is out or what please help.
Huskey48, I can’t begin to diagnose your RV, first because I’ve never owned an RV and know little about them and second because I would need a lot more info.
You have a separate house battery from your starting battery and it sounds like your house battery is dead but your starting battery is fine so everything else works. The first step would be to put a charger on the house battery and see if it comes back on.
I’m sorry, but beyond there is very little else I can do to help.
hi, just wondering where does the 80 amp fuse go, and where abouts on the positive end you have to fuse, regards dwayne
Dwayne, it goes directly to the positive battery post. You would put a 3/8 ring terminal on one end of the fuse and hook it directly to the battery post and use a butt-connnector to attach it to the wire going to the fuse block.
Fusing the fuse block is being extra-safe, because everything going to the fuse block will be fused at it. The only reason you should ever blow the 80 amp fuse is because the wire from the battery to the fuse block is damaged. For example, if that wire was cut somehow and wiring exposed it could short circuit and even cause a fire. But with the fuse there, it will blow before that can happen.
If that wire is run somewhere it can’t possibly be damaged, you don’t need a fuse.
Thanks so much for this simple explanation for wiring up 12v. This was what finally gave me the motivation to bring 12v into our vintage camper. Thanks again!
I’m glad to help Mary.
I really enjoyed several of your tutorials. In the fuse panel install you show fuses in the unused slots. Is that necessary ( to complete a circuit or something). Thought it might be a safety thing. Thanks and happy travels. Mike
Thanks Mike. No, there is no need for them to be there, I just put them there so I would have them when I needed them.
Great tutorial! Would this work for a 110-volt system in the van? I’m hoping to add a few outlets and lighting off of a converter.
whoops sorry…I meant an inverter not a converter
Kam, first, let me say I have very limited knowledge of 110 volt so I’m not the person to ask. But the fuse block is for 12 volt you wouldn’t use it for 110 volt.
When you wire the inverter you’ll put a fuse at the battery so it’s fused there, and the inverter should have an internal fuse of it’s own. For a distributions system for the 110 coming off the inverter, I use a simple power strip and it has it’s own fuse inside it.
That’s how I do it and everything is fused multiple times, no need for a fuse block or circuit breakers.
Thanks for the help Bob. I’m new to this wire gauge thing. Just curious as to how you sized your #6 gauge wire from your house batteries to the fuse block. Is the size of this wire based off of what the house batteries can produce (in my case 225 amps) or based off of the maximum load from my setup (maybe 10-15 amps)?
Hi Kam, there are online wire size calculators, you tell them the length of the run and amount of amps and volts that will run through it and it tells you the size of cable you need, here is an example:
With the fuse block it’s harder because you never know how many items will be wired to it, their sizes or how many will be on at one time. I guessed high on everything and 6 gauge was conservative. Better to be safe than sorry.
I see how you attached the ground cable from the Fuse Block to the negative battery post. How do you then ground the house battery itself? Do you just lead a cable from the negative on the battery and bolt to the vehicle frame?
Bill, that’s exactly what I do, but some people go back to the starting battery negative post instead.
If the amperage of all your 12 v devices is less than 80, would it be better to have a fuse on the wire from the fuse block to the battery that is closer to your overall amperage? (in other words less than 80). I have a classic little trailer with a few lights, (LED), a water pump, and a small electric air fan, an extra cigarette lighter type receptacle, all 12 volt.
Kenneyboy, the problem is that with a Fuse Block you don’t know what you might add to the block later.It’s biggest advantage is that it’s so easy to add extra items later just by plugging the wires into the fuse. If you are sure your loads won’t increase then yes, size the fuse to the load. But, be sure that if you later add more load to it you get a bigger fuse.
I’m looking to get one of these to act as a wiring hub for a bunch of led lights. What I’m unsure of is I see in the picture where the positive wires are supposed to be attached. But the led lights also have a negative wire. So is that the same thing as the Ground? I see in your image “- Ground”, so I assume that is the case. In regards to the picture, does that mean the 6 screws on the lower half are for the positive wires, and the six screws on the top are for the positive wires? I’m very, very new to wiring. I have a 12v car battery I’m using as a power station for a tent full of fans and led lights. Thank you in advance for your help.
Sorry, the sentence “and the six screws on the top are for the positive wires?” I meant to say and the six screws on the top are for the NEGATIVE wires (black)?
I figured that David, Yes, you’re right.
David yes, it has 12 inlets, 6 for positive and 6 for negative. The ones with the fuse holders are positive.
Hello Bob, I built a Tiny House and wanted to install a 12v (Boondocks) system. You are right, most people made the process way too complicated. Your explanation was the most practical of any I found on the internet! I have done my share of wiring but I was looking for a good wiring block and couldn’t find what I wanted until you put the link on here. Thanks for all the tips and if you were not a teacher …. you should have been! Good luck on your adventures.
Thanks Tim, I’m glad to help! Most of the time it’s black to black, red to red and just that simple!
Hey Bob … here is the Tiny House I am building.
Hi Bob, This was a very useful post. The one question I have: why do we need to have another fuse at the battery end?
I am so lost trying to wire 3 separate LED Light bars that I could just scream.
What I want to end up with is each of the 3 LED Light bars to be wired through my 6 circuit Blue Sea fuse box.
THEN… each of those 3 light bars, I want to be switched separately so that I can turn on just one or any combination of the 3 or all 3 at once.
My question is, HOW do I manage that wiring and what guage wires do I use? The pigtails off each light bar seem to be 16 guage wire but I have been told to use 6 guage wire from my battery to the Blue Sea fuse box.
This application is on my flatbed trailer so that I can light up the night back there if I have to load anything in the dark.
Is there a simple wiring diagram that I as a dunce can understand… or better yet, a simple video that goes into much detail on how to wire this up?
It has to be fed to me slowly so I can understand it. I just do not understand electricity but really want to learn. I figure this is my own little project and probably the safest on to learn on.
I broke a fuse holder putting in a fuse…can I use another slot in the panel? And just move the 12 volt wire
Can I switch slots in an rv panel to another one of a fuse holder breaks putting in a fuse