Reddit reviews Metra MC918-20 20-Feet Nine-Conductor 18 AWG Twisted Multi-Use Cable

In my experience, there are two schools of thought on wiring in accessories. The first and most common approach is to tap into the vehicle's existing wiring to power all your stuff off the main battery. This is a terrible thing to do, though, especially with modern vehicles as they can be very sensitive to voltage drops and changes. Plus, it introduces the potential for countless gremlins that will ruin a trip, and may cause your vehicle to not function.

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The second and better school of thought is to design a secondary electrical system from scratch, that is connected only once to the main vehicle and that is at the battery OR the alternator (Battery is easier and way more common). The second way gives you a lot more freedom to build your system, because it all comes down to math. First, start with your power source -- how are you going to power your stuff?

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If you are going to do a second battery, then that's your answer. Find a place to put it that is near the chassis (as in, keep the weight low) and make sure you can secure it so it does not become a projectile. Connect it to your main battery using a DC to DC Charger (CTEK is good, Redarc is great and priced to match, Renogy is good but cheaper and not as widely tested). Then, install a fuse block near the second battery and run your accessories to that. If you want to run everything off the main battery, then instead of finding a place to install a second battery, just do the Fuse Block.

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The Fuse Block then becomes what you wire everything extra to -- literally everything that didn't come with the car should go through this fuse block. It's only connected to the main battery by two wires. By starting with this principle, if there are any problems at all with your accessories, your vehicle should still run without any electrical gremlins causing your rig to sit down, and if you need to totally isolate the system, 5 minutes to disconnect those two wires is all it takes.

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As far as the accessories themselves, the rest then becomes pretty easy -- figure out the energy required to run the accessory (quality manufacturers will supply this info), figure out where you are going to physically install the accessory, and how long the run of wire will be to power it. Select a wire that will be appropriate for the current, and you are good to go.. If you have many accessories in one place -- lets say you want to have a dash panel with 4 switches in it -- then I recommend getting multi-strand cables, like this:

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https://www.amazon.ca/Metra-MC918-20-20-Feet-Nine-Conductor-Multi-Use/dp/B004H1KAMQ/ref=sr_1_2?keywords=vehicle+wiring+multi+conductor&qid=1563898763&s=gateway&sr=8-2

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This allows you to route one "Master" Cable to your switch block rather than running 10 individual wires. Obviously you'll need to buy the right gauge wire for your application.

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A few other pointers:

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• Grommets anywhere the cables pass through any hard surface.
  
• Shield cables as much as you can from wear and tear so that they don't short out.
  
• Put fuses in so that if you do have a short, power is killed immediately. I usually put fuses as close to the power source as I can. For instance, if I put a fuse 6" from my battery, and run that cable to my rear bumper, it doesn't matter where in the length of the vehicle I get a short -- the fuse will blow at the battery. If I were to put the same fuse at the bumper end, I could have a short anywhere along the length of that cable which could start fires.
  
• Make friends with dielectric grease and use it on every connector you see -- stock and accessories. Exposure to moisture (and the corrosion that comes with it) is the enemy of good electrical systems so this helps prevent that.
  
• Make sure you only use multi-strand automotive grade wire. Some folks I know have wired up things using household wiring, which is usually insulated solid core wire. That works fine in stationary applications but in a vehicle, the wire will move and bend and the multi-strand wire has way more flexibility.
  
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  We are hoping to use the ARB Linx system in our new rig to limit the number of wires we have to run. It's a fairly new option though so not a lot of people are familiar with it -- it might be worth a look though as it could save you some work.

Infinity Reference 5 channel amp - $239.99

[4 AWG amp kit] (https://www.amazon.com/Rockville-RWK4CU-Copper-Complete-Installation/dp/B019Z3RCG2/ref=sr_1_6?ie=UTF8&qid=1550159767&sr=8-6&keywords=4+awg+amp+kit) - $49.95

9 wire - $24.95

Additional RCAs - $19.99

4 channel LOC - $23.34 - You need this because you're keeping your factory radio

RCA splitter - $7.45 - To get the 4 channel LOC to 6 channels for the amp's input. There's maybe other ways you could do this, but this is what I would do because it'd be the simplest to swap the radio in the future.

Infinity Reference 6.5" for the doors - $56.95/pair x 2 = $113.90

Infinity Reference 3.5" for the dash - $48.70

= $528.37 + Installation which will easily run between $200 - $350

If you'd like to spend a bit more you might ask about sound dampening on the doors. Or you might save the extra and put it towards replacing the radio in the future.

You can make that existing wiring work for a 4 or 5 channel amp. You would just need to run the outputs back up to the radio harness or to each door. This makes it easy: https://www.amazon.com/dp/B004H1KAMQ/ref=cm_sw_r_cp_apa_i_uP6rDb766M3Y5


https://www.amazon.com/dp/B07N8KKR6X/ref=cm_sw_r_cp_apa_i_VS6rDbY2JVNC1
I just used this for a budget build recently. It would work with your speaker choices. At a 400$ budget you could do it and the 4 speakers and the speed wire. It will be loud. But you'll want to add a sub to it at some point for the low end that youll be missing

https://www.crutchfield.com/p_113DDX374B/Kenwood-DDX374BT.html?tp=20217&omnews=14403470

https://www.amazon.com/gp/product/B00XLXHVVE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B004H1KAMQ/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

You can absolutely connect all this to the factory head unit. The Pioneer amplifier that I linked to you can accept speaker wire inputs. No need for RCAs or line output converters at all. It's the white square 8-pin plug on the end of the amp. You'll clip each factory speaker wire in two, connect the side coming from the head unit to the white square 8-pin plug on the amp, then connect the output of the amp to the other side of the factory speaker wire going to each speaker. I'd recommend some 9-wire to help you with this. Easily connect all the head unit outputs to that, run to the rear in one small jacket, and into the amplifier.

Will do! I want to make sure im doing this right, I would take the RCA outputs and ford head and feed those into the amp, and then use this wire to connect the amp output to the cars factory wiring to feed the 4 cabin speakers?

https://www.amazon.com/Metra-MC918-20-20-Feet-Nine-Conductor-Multi-Use/dp/B004H1KAMQ/ref=sr_1_3?ie=UTF8&qid=1542597755&sr=8-3&keywords=9+wire+speaker+wire

Or should I wire the 4 speaker outputs from the ford head into the amp, and then have it amplified, and feed the output of the amp back into the speaker side of the harness?