How To Make A Power Relay / Fuse Block | Automotive Wiring

How To Make A Power Relay / Fuse Block | Automotive Wiring

alright guys yall have been asking for this one so I am going to do it and that is the power relay block

About the Author: Michael Flood


  1. Does the circuit breaker have to go next to the battery or if I'm going to run my power cable from the starter can I put it by that? My battery is in the trunk is why I'm asking

  2. I have done this but how do I allow current to power the new fuse box via ignition and not while the car is off because my battery dies after no start up for 1 week.

  3. Is the "switch wire" providing power to the actual cab switch? Or does the toggle switch need power supplied to it from another source???

  4. Pretty sad you didn’t saulder those butt splices. Yeah yeah it’s not necessary Bla bla. One day it’ll fail as is.

  5. This is exactly what i wanted to do to my car. Glad i found this easy install video. Right now i just have wires running all over with fuses inline cause i had no idea how to have a clean setup. Also that plastic is a great idea, i was looking into sheetmetal cause i wanted something to bolt my ecu on to as well as relays. Thanks for a great how to video.

  6. THIS IS FAIL CITY>… Running a 300a breaker on that tiny wire??? That wire will catch fire before that breaker goes. The amp rating is BASED on wire size and length, NOT what its hooked up too. 300A is rated for 25 FEET with 1/0 GAUGE…. so how the fuck is that 300a gonna work for a wire that small?

  7. Finally!!!! I have power watched countless videos that say they’re gonna explain relays and fuse box’s but all they do is tell me how they’re installing it their car and don’t explain shit about how to to wire the actual relays and how it all goes together. I had pretty much said this is the last video and I’m giving up. I’m so glad it was your video. You should do a how to video on how to do a how to do video. I finally get it. Great explanation. I had it all wrong in my head. I do have one question that I still can’t find an answer to. I have a 4awg cable ran to an lc7i LOC and amplifier using a distribution block. Can I run a wire off that same block to the fuse box? If so, what size wire? Thanks for the video and any help?l
    -White Boy

  8. Thanks for posting the video; you did a nice, clean job on the mounting.

    And really good choice on the tunes as well 🙂

    Happy New Year from The Great White North

  9. Is there a way a beginner can find crank and run power in a 92 mustang? I’ve been researching for two weeks and electrical is like another language to me. I don’t know what to do and I can’t find any local mechanics willing to come to my garage where the car is in pieces. Thank you!

  10. will this work for off road trucks? like pods, light bars etc? will the 40A relays be too much? This is awesome btw thanks !

  11. How to I connect this to my ignition switch? I dont want it to be constantly powered only with switch on. 1971 el camino

  12. 🤔 why common ground, most instances ground activating is better. Especially if you want more professional wiring.. yes building a car you are going to have your 12 running everywhere that you can “tap” into. “Tapping” into wires is not professional, and makes the all so fun game of “find what’s wrong” fun… only professional way to do it would be to run a positive from your central circuit, to the switch and would have to go back,

    Or ideally you’d want one nice block where everything is right there, fused and circuits all isolated. You want it that way, you don’t want to run your trigger for a switch from a random constant around, ex from like the radio. That block should have a constant, acc, and on terminals, for most things you would only have to run one wire out because ground is everywhere. If there is anything that gives off plus activation sure you can use it because again one wire, it’s outputting + and you don’t have a choice in that, it seems you are trying to make your job easier but in reality you’re not, and making it difficult for future people who may need to find what’s wrong.

  13. I think of the process like a TV remote. You sit in the big chair (drivers seat), you hit the power button on the remote(headlight switch), The TV comes on (headlights come on). No where in that did the 110v cable connect to the remote in your hand. It goes from the wall to the TV. You triggered a relay that connected the TV to the wall plug, turning it on. The switches on your dash are like little remote controls and the relays are THE REAL switches that turn shit on.

  14. I know this video is from a few years ago but would there only be one circuit breaker (ie between panel and battery) needed or should you run more than one?

  15. man, I've been trying to figure this out for two weeks. I'm stumped. How are you getting power to your relay white wire (86 – 85 black) with a switch located on the dash to energize the RELAY coil, which moves electro mag switch from 87a to 87 that closes the power to pin 30/pin 87 to activate your accessary?

  16. Sir when you say I’am going to run these yellow wires over here and red ones over here could you tell me what # that is on the relay???😁

  17. Curious if the type of fuse panels in any car are similar. Its hard to tell because of a lot of plastic paneling/molding around them (hard to see the screw down terminals in manufactured cars) . But if there like the ones you used in this video the install of the different gage wires is pretty much screw down terminals. Similar to the ground and white wire bus terminals in a home breaker box. Though i think there is a difference between the hot rod or hobbiest cars to the ones mass produced still…the fuse boxes just seem different perhaps they uses manufacture specific crimp on terminal ends / connector inserts into back of fuse box still a little confused.

  18. Also how are you tieing the 10 way fuse block to the bigger gage 2 , 6 , 8 gage battery wires you only show an important part of the entire electrical system of a car your missing the battery cables to fuse block to your 10 way fuse block. And any fusible links , circuit breakers you add. I have pretty good idea how it goes now but like to see the complete wiring from battery cables to the 10 way fuse block you created/addon as well.

  19. Love this video, will definitely refer to this! One thing was concerning me however, is a standard car battery capable of handling up to four different LED light bar connections?

  20. At 11:30 you mentioned things like this make you look like you know what you're doing… Everything except for the soldering part. Totally no needed with the proper crimp. Definetly wouldn't solder the ring terminals to the distribution block either.

  21. Nice job! I do prefere the panel mount Hella relay sockets though because you can mount those to you panel and then insert your relay. If you ever need to replace the relay, they are replaceable without having to unscrew anything.

  22. So what do you do if you want to use ground to tiger on the relay?
    I use ground to turn on my relays because vehicle has ground everywhere and if it shorts to ground no blown fuse and almost half the wiring.

  23. Do you have to run a seperate ground out of each relay? Or can they be just stacked on the same common ground? Also if I would want to run switched a d constant power could I do the same thing with this setup? Thanks

  24. Just a question, but why not run a single fused power to the coil on the relay from the fuse block? Then all you have is a single wire to your switch to control the ground side of the coil. Basically you control the ground with the switch, instead of the power. Then any shorts in the control side result in the relay being on, instead of arcing and blown fuses…

  25. Where 99% trying this will get it wrong is proper wire size to match correct fuse/breaker. If this is mismatched your wire could become the fuse/breaker. Seen this time after time. Great video my friend!

  26. Sorry to sound like a newb; does this basically create a central point to hook up multiple accessories (lights, etc) for a vehicle?

  27. amazing video, just one question I'm begging you to answer. The switches provide power to close the relay but where would the switches get power from. I was thinking the battery but then what would be the point of the relays, you could just have the power go straight to the switch after the fuse.

  28. Was about to install my newly built relay board (just like yours) and discovered I don't know where "both" my toggle switch ends connect to….help!?…do they "both" go to the switch side of the relay board?

  29. I have been all over the interwebs searching trying to figure out how to wire up a power windows conversion and add electronic door locks to my standard truck. thanks for the educational video.

  30. You are amazing. Learned a great deal in just a short time. Will put it to use on my 67 Bonneville. There are just too few circuits for today's gadgets.Really need to upgrade. Thanks for sharing.

  31. Perfect Video! No "blah, blah, blah", no BS, clear, concise & straight to the POINT! Even went out of your way to list all parts needed to build this! What else could you ask for?! Thank You!! #AmeriCuh

  32. Might I suggest you using rivets for the mounting of the relays and power distribution blocks to eliminate the need for long screws sticking out on the back side, even plastic rivets if plan to be making changes. They are easy to cut, cheap to buy and look clean. Other than that, extremely nicely done.

  33. I had a question about a 5 pin relay. the relay for my fans is 4 but my fuel pump kit is 5. is there a suggestion for the 5 pin relay?

  34. great video and very professional end product. If I might make two suggestions to improve the final outcome if only marginally, first I always use marine grade awg rated wire it is tinned copper and will not corrode in normal automotive use and only costs a few cents more. Second I use aviation style ratcheting crimpers they work much better and do not require soldering which will prolong your wiring life by not removing flexibility from the wire.

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