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Putting Wires together and trying to match the fuses.

Discussion in 'Toyota Trucks & SUVs' started by Trd174x4, Apr 29, 2021.

  1. Apr 29, 2021 at 12:35 PM

    Trd174x4 [OP] Active Member

    Aug 27, 2017
    2017 quicksand trd 4x4 Tacoma
    I know this is going to sound Dumb, but please entertain me.
    I have Lights, Stereo, and extra Accessories added to my 2017 OR. It looks like a bird’s nest around the batter.
    So, what I have decided to do,
    is install a distribution block and Circuit breakers(instead of fuses).
    Make it all nice and orderly.
    For my lights I have a set of Ditch lights (inline 30amp fuse) and I have a Light Bar (inline 30amp fuse). I want to combine these two wires and make it one. Removing the 2 (30amp) fuses and replacing with one (50amp)circuit breaker or (60 amp).
    Is my math correct? Or do I need to keep them at 30amp? not very good with electrical and I know there is someone on here that this answer comes easy too them.
    thanks guys.
  2. Apr 29, 2021 at 12:46 PM

    0xDEADBEEF River Trash Aficionado

    Mar 2, 2019
    You could, but you're going to have to verify that the wire downstream of that breaker can handle 50 amps. Otherwise you could have a short somewhere and the breaker would let a full 50 amps go through the wire. If that wire isn't heavy enough (6 awg or thicker), you run the risk of melting it.

    I would keep them separate.
    tirediron and whatstcp like this.
  3. Apr 29, 2021 at 12:50 PM

    tirediron Well-Known Member

    Jan 19, 2019
    First Name:
    Victoria, BC< Canada
    2022 4x4 Sport, Auto, BCM
    What he said. 50 amps is a lot of current, and while it’s unlikely, in the event of a dead short, you could wind up trying to pul that through a wire and fixtures only meant for 30. A certain way to let the magic smoke out!
    Enigma8246 likes this.
  4. Apr 29, 2021 at 12:59 PM

    whatstcp currently drunk so don't listen to me

    Aug 3, 2018
    First Name:
    Fontana, CA
    2006 Tacoma Regular Cab 2.7l 4x4
    King + Archive Relocation Wheeler's bumps +hydros
    ^ what he said. Keep them separate. One option you can do is run a thicker gauge wire with a 50 amp inline fuse close to the battery that then runs to a add on fuse distribution block. These have inline fuses for each circuit you add on. Sort of like this one. There are many options so choose whichever one is right for you.

    Also, I would suggest to anyone, including OP, to try and measure how many amps your devices actually pull. Most wiring harnesses come with generic 30 amp fuses, but often the devices won't pull any more than 10-15 amps. For example, most ditch lights pull about 3 amps each max. That's about 6 amps total so you can swap out that 30 amp for a 10 amp fuse. Leaves 20-30% wiggle room just in case but there's no reason for that circuit to pull more than 10 amps at most (at which point the fuse pops) so why run the risk of letting up to 30 amps run through it. Depending on the light bar, then you might see somewhere around 15 amps depending on the brand (Amazon 30 inch light bars usually pull less than 10 amps :anonymous:)

    edit: reading your post again it seems like you are already planning on doing what I suggested, that's my bad for reading too fast. Now from what I understand from reading again is that you want your ditch lights and light bar to be triggered by one switch, therefore splitting from a single spot on the distribution block? Possible, but you would have to take wire gauge into consideration for the whole circuit amongst other things. Not the idea you wanted to hear, but if you're unfamiliar with wiring up aftermarket stuff then getting a prefabbed panel like switchpro/spod/etc. will make life a lot easier. Just my opinion
    Last edited: Apr 29, 2021
    VirusCage likes this.
  5. May 3, 2021 at 3:36 AM

    Wyoming09 Well-Known Member

    Apr 24, 2015
    New Tripoli Pa
    2000 Work truck 5 speed 4x4 3.4
    Super Springs
    Increasing that Circuit to 60 amps means it will not open till the current draw hits 60 amps most likely long enough to melt the harness.

    unless both circuits wire is increased in size.
  6. May 3, 2021 at 4:06 AM

    Enigma8246 Well-Known Member

    Mar 25, 2014
    First Name:
    Central Arkansas
    2007 4Runner Limited 4WD V8
    I would start by verifying that you actually need a 30 amp fuse for each of those lights. You have to have a pretty big light bar to need 30 amps (Rigid 50" pulls 25) and I would be very surprised if your ditch lights actually need that.

    Having said that, even if you can do it, it's still somewhat of a 'best practice' to keep them separate. For example assume they're on the same circuit (switched separately) and your ditch lights pull 10 amps (conservative guess). If your ditch lights but not your light bar are on and something in them malfunctions, the fuse being much larger than what they need could allow them to damage themselves before the fuse blows. This is unlikely and given that the ditch lights came with a 30 amp fuse the manufacturer probably agrees but it's why the best practice is to provide separate fuses.

    Like others have said you would have to verify that the wiring could handle whatever you increase the amperage to.

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