MXT500 MIDLAND RADIO

I guess I could cut the wire somewhere between the fuse and the jack that plugs into the radio, feed it through the firewall and reattach, right?

 

I have had to cut and re-splice wires to get through the firewall. I don't especially like the extra joints, but it seems to work fine. I solder, use waterproof shrink tube, tape, and corrugated wire loom. I don't want to worry about connections coming apart or corroding so I kind of over do it, but beats looking for short circuits later. I want my lights and radios to work when I need them!

 

I was able to push the wire harness through the main harness firewall grommet without too much trouble. It required untaping the end of the grommet hole around the harness but that's just electrical tape if you want to replace it after wiring. You can push the power leads through that grommet from either direction so pushing the fuse blocks through that hole isn't necessary.

 

Also, since nobody mentioned it, standard practice is having the fuse closer to the battery than the item you're powering...just an FYI.

 

If I had to cut wires and rejoin them I was planning to do this:
https://www.youtube.com/watch?v=tQjfXwJkNLk
Is this reasonable in a vehicle

 

You could do that but I'd change one major thing; rather just wrap it in electrical tape; I'd use weatherproof heat shrink to cover the connection.
Something like this:

$17 Wirefy Heat Shrink Tubing Kit 180 PCS - 3:1 Ratio Adhesive Lined, Wire Shrink Wrap Tubing - Industrial Heat-Shrink Tubing - Black - Shrink Wrap Tubing | Trusted UL Certification

https://www.amazon.com/dp/B084GDLSCK

Personally? I'd use these with a good ratcheting crimping tool and a heat gun:

$35 250PCS Yellow Heat Shrink Butt Connectors AWG12-10,haisstronica Marine Grade Heat Shrink Wire Connectors,Tinned Red Copper 1mm,Waterproof Insulated Crimp Butt Splice Electrical Connectors

https://www.amazon.com/dp/B09B9NP9F4

Now take all of this with a grain of salt...I'm not a 12V installer by any stretch of the imagination but I've used these methods before and none of the vehicle's I've worked on have burnt to the ground lol. YMMV. If you really don't feel comfortable, enlist the help of some local HAM's or (if you don't mind paying) reach out to a local emergency vehicle upfitter. But if you do it right and not cut corners (like running power cables through door jambs lol), I don't think you should run into any trouble.

 

I’m wiring mine the same as you’re planning to. You can cut those fuses off since you’re wiring to an aftermarket fuse block. Just wire directly from the radio to the fuse block and use a 15amp fuse in the fuse block. You can keep the fuse holder on the negative wire if you want but it’s not necessary unless you are connecting the negative wire directly to the batteries negative post, which isn’t recommended anyways. You’ll want to run the ground wire to a bussbar if you have one on your PowerTray or to the inside of the fender, where the battery’s ground cable is attached.

 

I assume the a5A fuses are standardized? Like could I use these?:

$6 Bussmann BP/ATM-15 15 Amp Fast Acting Mini-Fuse, Blue

https://www.amazon.com/Bussmann-BP-...t=&hvlocphy=1021085&hvtargid=pla-568657539528

Edit: Maybe I should get these since they are from Blue Sea Systems (the maker of my fuse block)?:
https://www.bluesea.com/products/5242/ATO___ATC_Fuse_-_15_Amp

 

One other question: it looks like the smaller fuses just plug in to the fuse block? I assume the fuse should go into the slot on the fuse box where I intend to put my radio positive wire ahead of my putting in that wire?

 

Blade fuses are standardized but there are multiple standards so just be sure to get the physical size that fits the fuse block you will be using. Each size standard is available in a range of amp ratings.

The first link you posted looks like a "mini" which is designated by ATM in the fuse part number. The second link is a "regular" size, aka "ATC" or "ATO". There is also a larger size, but those are not common in the fuse ratings that would be found on most vehicles.

 

correct. The bottom of the fuse block that you will use should have a common wire or buss bar that connects all (or sometimes half) of the fuse outlets on one side and your wire powering whatever circuit/device you want to install will connect to the other side of the fuse slot that you want to put the fuse in, often via a small threaded post with a nut or a socket with a setscrew to clamp onto the wire. There are probably other designs, but they should all work the same way electrically.

 

The description of the block (https://www.bluesea.com/products/5026/ST_Blade_Fuse_Block_-_12_Circuits_with_Negative_Bus_and_Cover) says is accepts ATO or ATC fuses. Cool. Thank you.

 

Do you have a sense of what size terminal eyelet would be appropriate for that fuse block? Thanks

 

The specs tab on the link your sent says the buss stud size is #10-32 and the terminal screws are #8-32.

A #10 screw uses a 3/16“ nominal hole diameter so I would get terminals with that size hole if possible.

A #8 screw uses a 5/32" nominal hole diameter, but that's so close to 3/16“ that I wouldn't worry about trying to find a smaller terminal eyelet to fit those, if they even exist.

You could probably go as large as ¼" on the eyelets if you had to without any issues

 

Do you have wire strippers and good ratcheting crimpers to attach the terminals to the wire? Insulated terminals can not be crimped securely with pliers or the wrong crimper die, the nylon jacket prevents the metal conductor from closing securely with the wrong crimping tools.

 

You don't need to keep them if you are going into your aux fuse block then to the battery. Those fuses are if you are going directly to your battery. There really isn't a need for you to have pos + and neg - from the radio to your aux fuse block... then to have that line fused between the battery and the aux fuse block. You only need one fuse between your equipment and the source.

Remember, the blue sea can handle UP TO 30 Amps. Your radio is rated for much less than 30 AMPs -- 30 amps would fry the circuits so just be sure to look at the instructions for how many amps it is rated for then fuse appropriately (probably 5A or 7A).

 

The MXT575 factory harness uses a 15amp fuse, so that’s what I’ll be using in my fuse block. Per Midland, the max power it will pull is 10amps, so a 15amp fuse sounds right.

 

I got these for stripping and crimping:

$25 ENGINEER precision wire strippers for thin gauge wire, professional grade, super sharp carbon steel jaws. Made in Japan. pa-06

https://www.amazon.com/dp/B001HQMWNY/?coliid=I200KTL0Q53NVD&colid=6QWZTAZD5F4P

$80 Wirefy Crimping Tool Set 5 PCS - Ratcheting Wire Crimper - For Heat Shrink, Nylon, Non-Insulated Connectors, Ferrule Terminals

https://www.amazon.com/dp/B07Q32PYP3/?coliid=I1K00DYNQ3E8LI&colid=6QWZTAZD5F4P

 

Those should do the job nicely

 

Thank you!