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Adding 3 new wires to 1 fuse in fuse box in car

  1. Aug 26, 2014 #1
    I wanted to install a few cigarette lighters in my old 1996 Toyota Camry that my sister just gave me since it only comes with one, and I want to have a dash cam/parking cam AND to charge my phone, and while I'm at it, add one in the back. I located the fuse box, and will find an accessory fuse that only turns on when the car does, but the box is already full of fuses, no empty spaces for new ones...As soon as my volt meter comes in the mail, I can see which turn on only when the car does, and look what each is for so I don't use something necessary... I know ones for the existing cigarette lighter with a 15A fuse.

    Here's my dilemma: I want to use one fuse and attach 3 or 4 of the 12 gauge wires to it (I chose 12 so the wires wouldn't be the limiting factor, I'll see the amp rating of my devices so I can put a low enough amp fuse so I don't blow my items I plug in). I'd get a fuse tap, but the wires that come on it look a bit flimsy, and I want to split it 3 or 4 ways. I basically want to know how to split my power 3 or 4 ways. I have enough wires, I have extra fuses that I bought, and 10 inline fuse protectors too (full list below)... But how do I get 3 or 4 wires to connect to the 1 fuse? Do I connect 1 to it, then use a quick splice wire tap that cuts into the protective outer layer of the wire, then put heat shrink on it, then tap that one, then tap the next and the next? How would you go about splitting the current 3 or 4 ways? Is there any other type of wire splitter? Like how we have for coax cables that can split the power? Is the

    I ordered a few cigarette lighters from eBay some 12 gauge wires black and red 50 foot ones, a 10 pack of 12 gauge inline fuse protectors, yellow butt connectors (for 12 gauge), some ATC fuse taps (some said hot, some didn't) and crimp on female parts that attach the 12G wires to them. some crimp connectors that would attach my 12G wires to the cigarette lighter, heat shrink tubing (0.5mm) wire protectors an assortment of ATC fuses (standard size, not mini). Solder, a soldering iron, wire cutters that come with the crimping ability and stripping ability. A volt meter.

    I have a drill, which I'll find before the items get here, but I'm sure I'll need to buy bigger bits for it, or maybe use the ones I have and just extend the hole.
    Right now, the car needs some work, and the plastic is missing from under the steering wheel, it needs new door handles, both power windows on the passenger side don't work (maybe a blown fuse or loose/faulty wire), may need a new ignition cylinder, and the wires are already exposed, so I figured I'd get this done before my mom and her boyfriend go to get the pieces for it and get them attached and fixed up.
    To be honest, I've never done this before, but I did a hefty bit of online researching, and YouTube video watching, and found all the parts I'd need, and went through it in my head how I'd do it many times, but just never saw anyone doing more than 1 cigarette lighter install...and I'm trying not to tie up too many fuses since the guy my mom used to install her viper will need some for the viper he's going to install in mine...after it's fixed up.

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    Last edited: Aug 26, 2014
  2. jcsd
  3. Aug 26, 2014 #2


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    Welcome to PF.
    By cigarette lighters, I assume you mean sockets for them.
    If you are going to plug cigarette lighters into more than one of them at the same time, then you will need more fuses.

    But; If you will just plug low power devices into them then no more fuses are needed. So; Tap your red wire into the power lead to the existing lighter socket. Run that to the red lead of all new sockets. Connect the black leads of the new sockets together and connect that to the chassis of the vehicle. Make good soldered or tightly clamped connections. Insulate the connections.
  4. Aug 26, 2014 #3


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    Welcome to the PF.

    Sounds a bit dangerous, but here is what we use to wire up power to HAM radio gear in cars:


    The Anderson PowerPole connectors and distribution strips offer a clean, professional (and fused) way to handle moderate power in 12V systems (like in cars). Check them out to see if you can use them.

    Attached Files:

  5. Aug 26, 2014 #4
    Ok Berkeman, I think I see what I can do with this. Looks like it'd have to be hooked directly to the battery, right? Then I can turn on the switch when I'm ready to use it. I wish I could find something exactly like that that would turn on with the car like the accessories in the car do. That's what I was looking for at first, but don't know what to call them, or if they're even sold. I'm going to look at prices for this.
    As soon as my parts come in, I'm going to look to see what I can do.

    Oh, & sorry. I meant sockets for cigarette lighters to power low power devices like cell phones/tablets, dash cams, GPS, etc. Not the actual one that can light a cigarette. Thanks for clearing that up for me. I'm making the red leads for the cig lighter sockets too btw. These come without wires so I done have to worry about wire quality. So you're saying I don't even need to tap the fuse? Just tap the wire with a quick splice wire tap? I was planning on starting closer to the source just in case the cig lighter installed had an old high gauge wire. I will check out the wire this weekend when I'm off and see how durable & big it looks. Can't start anything but mapping out until I get the parts in the mail though, sigh.

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    Last edited: Aug 26, 2014
  6. Aug 26, 2014 #5

    jim hardy

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    I dislike tapping into battery.

    What i would do:

    Mount something like this near your existing cigarette lighter where it's not too much of a gymnastic exercise to get at it.:

    That's a Cole-Hersee , most boat or auto parts stores should have it. That image came from Oreilly's auto parts. I like it because it has a screw for every wire you'll need.

    Remove the wire from rear of existing lighter and connect it to the fuseholder's + bus.
    Now that bus and the wire to it are protected by your exiting car fuse.

    Wire each new outlet to the bottom of an individual fuseholder.
    Install a 5 amp fuse to feed each of your new outlets.
    Now you can wire those with smaller wire, say #16 which is a lot easier to handle.

    That way you can plug a 5 amp load into any or all of them.

    Your original outlet, where you stole the power wire from to begin with, can be wired to the fourth fuse position.. If you expect to use a cigarette lighter or 100 watt inverter in that one, use at least #16 wire and a 10 amp fuse. If it's just for small electronics you could use a 5 amp fuse there too.

    Ground wires for new outlets ought to run along with and adjacent their power feed wires, be same size, and connected to car chassis metal at same place where original outlet was (or still is). You can collect them at the - bus of that terminal strip.

    Now your add-on is an obvious add-on.
    And it'll tell you which fuse blows - you only lose one outlet. If you lose 'em all, it's the original car fuse.(or else your ground wire came off)
    Keep a box of correct size glass fuses in glovebox.
    Probably you could find similar blade fuseholders...

    Here's a pretty decent introduction to car stereo wiring and fusing.


    my two cents
  7. Aug 26, 2014 #6

    Thanks! I'm going to try to find something like that but with blade fuses (only because I bought a bunch of blade fuses already, lol) but this looks awesome!!! If you can think of it, someone already invented it. :)
  8. Aug 27, 2014 #7
    Which one would you use? With Screws, or connectors?

    My cigarette lighter sockets are coming from China, so they will take a while to get here anyway.

    There are 3 fuse box distribution blocks that I'm looking at on eBay.

    One has screws, (China)


    one has a male connectors, (China)


    and the other has male connectors and grounding screws but no cover for fuse box was listed (USA)


    I'm wondering if the one with screws is more secure only because If something happened to a screw, I could just replace the screw, but if something happened to the male connector, I'd have to do some soldering and more work to fix it.

    (I already have these coming in the mail)


    $_57.JPG Female



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    Last edited by a moderator: Apr 15, 2017
  9. Aug 31, 2014 #8

    jim hardy

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    It's a personal preference.

    I worked in an industrial place where we allowed only ring lugs like you pictured. They are secure.... but laying on your back holding a flashlight in your teeth with dust falling in your eyes from under the car dash, trying to manipulate a flat screwdriver into a slotted screw head that's in the shadows is no fun. If you buy screw terminal connecters - look for Phillips heads.
    And prefabricate your wires - do your soldering on the workbench.

    if instead you use push-on connectors get the ones fully covered by insulation. Be aware they come in different widths...

    For car work a good crimp is okay but requires a tool. I have this one from a home supply store.


    but a lot of people use this:

    they're available most everywhere in varying degrees of quality.

    If you anticipate doing a lot of electrical work get yourself a really good crimp tool. For just occasional odd jobs the cheap little flat crimper will get you by. Its thread repair capability is handy.
    A fellow really ought to have both tools. Believe me word will get around that you're handy.

    Lastly- when you crimp with the better crimper put the dent opposite the split.
    The last ten pages of this document about crimp connectors are informative.

    ol' jim
    Last edited by a moderator: Apr 17, 2017
  10. Aug 31, 2014 #9


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    I've done lots of mil-spec wiring on ships where we only used ring lugs (it can be a pain but the work was always inspected for the right terminals). Rings are the only thing I would recommend in a car for power connections to a terminal strip, much less likely to loosen up during temperature shifts/vibration because of the uniform compression force on the edges when tight and stay put even if slightly loose.
    These little babies make the job much easier when working in tight or awkward spaces.

    Last edited: Aug 31, 2014
  11. Aug 31, 2014 #10
    You guys are so helpful! Thanks :)

    This is the tool that I ordered online. A little el-cheapo multi use one since I don't anticipate using it more than once in a while.
    I think I'll attach the majority of my wires to the 6-way terminal fuse box before I go under the dash. The only ones I'd have to be under there for are the ones that'll attach from my power source to the 6-way terminal fuse box. I'll even keep the wire that was originally going from the cigarette lighter to the power attached to the cigarette lighter, and attach it to the 6-way fuse box. I may change the fuse though, depending on how big it is (seeing as there will be fuses in the 6-way fuse box anyway, I think I should check the amp rating on all the devices and make it powerful enough for everything that will go in there to go in at the same time.) They'll each only pull the amount of power the device asks for anyway, right? So I don't have to worry about fuses blowing b/c the fuse before it is more powerful? The weakest link will not be the wire, which will be a 12 gauge, which can safely accept up to 20A...All devices connected at once definitely won't exceed 20A anyway, so I may end up using a 15A fuse there if it isn't already there.
    Guess I won't need the in-line fuse holders for this project, but they're still useful to have around. :)
    I haven't gotten it yet, so I'm not sure if the holes I pointed out in red are for mounting, or for grounding, or for both... I'm still waiting for it to come in the mail. They go all the way through
    and seem to be smooth, not ridged.
    I'm going to be using the crimp on ring terminals, but will solder it too for good measure.

    Last edited by a moderator: Apr 17, 2017
  12. Aug 31, 2014 #11


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    The tool you pictured is a wire stripper, not a crimper. You need something that will do good crimps. Without a good crimping tool I cannot recommend crimping at all. Bad crimps are worthless, solder if you cannot get a good crimp. Test all crimps with a firm pull, if the connector comes off, you did not get a good crimpl
  13. Aug 31, 2014 #12
    All good suggestions so far. Just note, you're fusing to protect the wiring - not the attached devices. If you wire with #12 wire and come off a single point (star feed), all you have do is use one fuse to that point and size it for #12 wire. If any one load draws more than the fuse rating, that fuse will blow and protect the wiring from a melt-down. Of course, all the outlets connected to that point and its associated fuse will go dead until the overload is removed, and the fuse is replaced. An important point: wiring to the single point has to be #12 or larger. If it were smaller and you fuse for #12, the #12 would be protected in case of an overload, but the smaller main feed wire could undergo a melt-down.

    In many cars, there is an accessory post, which is switched hot when the ignition is turned on. Coming off this point will accomplish what you mentioned. Again, make sure that accessory point can support the load you fuse for. Chances are, it's already fused with the appropriate size fuse.
  14. Aug 31, 2014 #13

    jim hardy

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    i think i smell trouble.

    The fuse that's in the car now is sized to protect that wire going to your cigarette lighter.
    It is not intended to protect what's plugged in or connected to the cigarette lighter.
    So you must NOT replace that fuse with a bigger one. That risks burning up the wiring harness which is a really expensive repair.

    EDIT Assuming you power the six way fuseblock from the existing cigarette lighter, the total load you connect to all your outlets must not overload that wire going to your cigarette lighter. That's why it's fused.

    Chances are you won't have 5 amp loads plugged in everywhere at once. And if you do , you dont want wires melting.

    If instead you run a new wire from power to the six way, as RBTO suggests, yes you can fuse it for whatever that wire can take.
    Last edited: Aug 31, 2014
  15. Aug 31, 2014 #14


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    I'd just like to point out that a car battery can supply loads of current (!000A, on a good day). This will destroy any cabling that happens to get connected across the terminals - or when the end falls onto some clean metal of the chassis (and possibly set fire to the car). Hence, if you are giving yourself a fresh feed from the battery, you really should make sure that any fuse you put in the circuit is as near as possible to the battery + terminal. That way, if you happen to get a short to Earth, the fuse will blow and you will not have a fire on your hands. If the car's own wiring is not done like that, it will be because they have very reliable connectors and insulation upstream of the fuse. As a beginner, you cannot assume that your construction quality is bomb proof. Also, be very careful using tools near the bare battery terminals. A screwdriver across both terminals or + to Earth could spoil your day (and your battery).
    I always tend to bring up this boring safety thing but it really is important. Good luck with your project; you are certainly doing your homework for it!
  16. Aug 31, 2014 #15
    Thanks. I really need to work on my wording, lol.
    *EDIT*I'm basically going to take the wires that were connected to the cigarette lighter and remove the ends closest to the accessory port -thx that's the word I was looking for- (paying attention to which went where) and connect that part to my new 6 terminal fuse box. So the power will go from the accessory port to my 12G wire, to the input on the 6 terminal fuse box to the its own fuse to the screw attached by a ring terminal crimped and soldered to a wire (12G if it's the new cig lighter, and whatever gauge the original one was if it's the old cig lighter) to the cig lighter, and ground the (-) one. (So I won't disconnect the parts directly connected to the cigarette lighter, but the part that was once connected to the accessory port of the fuse box so I don't have to worry about that wire taking the load of all of the devices, just the one device) *EDIT*

    I'll use my new 12G wires and connect from where I removed the original wires (that was connecting my cigarette lighter to the accessory port of the fuse box marked cigarette lighter on the fuse box, yay they marked it.) to the input of my new fuse box terminal and ground the (-) one. (I haven't followed it all the way there yet, I was waiting for my tools to get here first so I can have a good look at everything)
    That way, I'll have my strongest cables (the 12G ones) connected to the input of the fuse terminals, and the weaker one (the original cig lighter) connected to only that 1 cig lighter. I was then going to use the rest of my 12G wires to connect my new cigarette lighter sockets (power only of course, not for actual cigarette lighting) to where I want them in the car. I don't think I'll use up all of the terminals, but at least I'll have space for new additions should I need to do so at a later time.

    And darn, this is really just a stripper, not a crimp tool?

    grr ebay. It said it was a "Plastic Handle Wire Stripper Cutter Crimper Automatic Crimping Striping Tool" in the description/title. It was only like $5 anyway, but I basically wasted all that time waiting for it when I could have gone to home depot or something and gotten one...Can't drive it yet or turn it on to do any power tests until I get the ignition lock cylinder replaced (By a pro) or I would've gone already.

    Last edited: Aug 31, 2014
  17. Aug 31, 2014 #16

    jim hardy

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    Last edited by a moderator: Apr 17, 2017
  18. Aug 31, 2014 #17
    A lot of cars have a "fusible link" located very near the battery which acts as a main fuse for the entire electrical system. It's kind of intended as a last resort if fusing elsewhere fails to protect, or a main feeder rubs its insulation through and shorts to the frame of the vehicle. Even with the fusible link, there have been a lot of wiring harnesses that have gone up in smoke when a short developed (I had one do so on a new vehicle some years back). They also can be problematic, because when one opens, it's not that obvious (it looks like a short chunk of insulated wire), and can take some testing to determine that it's blown. Of course, nothing in the car has electrical power when that happens (except emergency flashers which are often wired ahead of the link).

    It's best to disconnect the positive terminal of the battery when doing any electrical work just to be safe. That will kill all power to the vehicle and make it a little easier to work on things without the worry of something hot touching the frame. Try not to make too many sparks (when disconnecting or reconnecting the battery) around the battery, because batteries have been known to explode due to the hydrogen gas they produce when charging. It probably isn't an issue if the battery has been sitting for a time, but be particularly careful if you've had the battery on a charger, or have been running the engine for a while either of which could accumulate some hydrogen gas.
  19. Sep 1, 2014 #18

    jim hardy

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    good point. I'l suggest a fine adjustment to it though-
    disconnect the negative terminal instead.
    Reason for that is should your wrench accidentally touch nearby metal there'll be no spark.

    Negative is "ground" on virtually everything automotive nowadays.
    Last car i saw with positive side ground was a Volkswagen Beetle around 1969. Early '50s Chryslers were positive ground
    Always remove the grounded side of battery first and replace it last.. That way you can't make a spark from the other one either.
    But i digress... sorry.
  20. Sep 1, 2014 #19


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    You beat me to it, Jim.

    *Very* important to disconnect the negative terminal first. Negative is the first thing you disconnect, and the last thing you re-connect.
  21. Sep 2, 2014 #20
    Okay. Good thing you guys said something about that. I haven't turned my car on in a while because the lock cylinder needs changing, so I was just going to go in there, but better safe than sorry.
  22. Sep 4, 2014 #21
    Yay, I'm practically ready. I can start working on it tomorrow morning if I can get the professional to install the lock cylinder any time soon, lol. I don't have the fuse box terminal yet, but I can drill, and wire everything else and have it set up so it's only waiting for the fuse box to attach the last few wires. I'm going to buy a crimp tool and as soon as my car is driveable, I'll bring it to my mom's friend's house and work from there. (My drill needs a power source, and I don't have an AC/DC converter... it only uses 4.2A, but still.) Yay, thanks guys!!!

    Attached Files:

  23. Sep 7, 2014 #22
    ring terminals too small to go over car battery

    So, while someone was installing my ignition key cylinder, I decided to start hooking up my cigarette lighter sockets, running the wires and everything. They said I should just connect it to the car battery instead of trying to get to the wires for the cigarette lighter. I said it would be always on, he said it's okay, because the ones in some cars are like that, and it's fine... BUT the ring terminals I got were too small to fit over my car battery...da da dum These were the ones I had gotten...
    $_12.JPG but from a different seller.
    So I see others that are different. $_57.JPG
    They aren't ring, they are more horseshoe shaped. Do you think I should try those instead? I have the wires strung through just waiting to be hooked up, got the power from a neighbor who has an extension cable & I was able to use my drill and make a perfect looking hole. I'm getting different screws (shorter but the same diameter so my ring terminals can ground my ground wires. Found a great spot, but need smaller screws and nuts and bolts to fit those screws.

    So do you think it would better to get the horseshoe ones #6 like listed above instead of these #6 below so I won't be trying to go with this and praying it's not too small again?

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  24. Sep 7, 2014 #23

    jim hardy

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    Be circumspect of people who sound confident but do not explain their reasoning.
    I do NOT like tying directly to car battery.. That bypasses ALL the safety stuff built into the car. Translate - asking for trouble .
    If you do tie to battery go to auto parts store and buy a "fusible link" and put it right at battery end of your wire.
    You can usually find a better place than the battery post to tap in - like at starter solenoid or that post on fusebox mentioned earlier.
    My buddy's Ford had two such fusebox posts, one switched and one unswitched. You'd be best using a copper or brass nut there. Probably metric threads though - yukk.

    Does your cigarette lighter go off with the ignition? Mine in several different cars don't.
    So what if it does? That has a bright side - a load won't run your car battery down while you're in the movie theater with someone you'd like to impress.
  25. Sep 7, 2014 #24
    I was thinking the same thing. I have 12G in line fuse holders that I'd hook up to the battery end, but I would prefer it to go on with the car for just those reasons. I don't want to try to rely on my memory and one day forget something charging in there and it's dead in the morning. Now that he showed me how to remove a few more parts, and I could actually do it, (I made sure to watch what he was doing, and asked questions too, and tried for myself. He even showed me a great place to ground my wires) He was dismissive at first, but once I told him what I was going to do, and why and how, he got over me being a female & showed me a few tricks. My main problems were removing a few plastic parts, but they come off easily if you know what to do. I think I'll go under there later and do it to the area where the cigarette lighter is connected. It looks like the radio shares a spot with the cigarette lighter, so I'll take that into consideration too. He said to use wire taps because the 6 way fuse box terminal is overkill, but I like the fuse box terminal. Less loss, less risk, and everything is fused...plus I already bought it, lol, just waiting for it to come. And you guys have been helping me and, with your help, I've been doing research on doing it this way. So I feel like I trust you guys more. :)

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  26. Sep 7, 2014 #25

    jim hardy

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    Well i certainly had no idea ! Bravo for you !

    I brought my two daughters up to be handy with tools. It has turned out well. Good for their self confidence, and it saves thousands of dollars these days to be handy. Kate replaced the master computer board in her 60 inch flatscreen TV for just $115 .

    You'll be glad you used good terminals and the fuse block. Even if you're the only one who knows.
    I don't like those wire taps because they tend to cut strands in the wire and make a weak place.

    I expect you could teach your helper some things now about fusing.

    Proud of you

    old jim
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