Electrical Wizards Needed...

[nutt7]

So I think I have an understanding about wire size and length but I would like to get more input.

I bought an F150 fuse box and plan to use it for under hood power distribution. Not all the wires are as large as I want, and finding the correct terminals to redo these wires is impossible. If I want, lets say, a 10ga wire to run to my lights, but my only fuse or relay option has a 14ga lead, would it be bad to have 6 inches of 14ga wire in there? My understanding is that it will be fine since it is so short, although I should fuse the circuit for the 14ga wire. Am I right?

Some say it will bottleneck the current, others say it will be fine because there is insignificant voltage drop over a wire of that length (think fusible link or fuse element) What do you think?

I have also compiled a series of charts of wire size to recommended current, fuse size, max current etc if anyone wants to see it. (of course not one chart reads the same, but all are ballpark close in numbers)

 

[Blue85]

What are you proposing is sort of OK, but from 14 to 10 might be a stretch. It's true that the resistance of a few inches of wire is not that big. Of course you should solder and heat-shrink the wire-to-wire interface. Crimp-on connections will be crap and ruin the whole project unless you have some fancy equipment. When I spliced a Ford electrical center into mine, I spliced a lot of wires into the stock wires by soldering. In some cases I was jumping up a couple of AWG.

If you are planning a lot of current, you need to consider the terminal contact area and the crimp area. The terminal to fuse is probably the same for all of the fuses of the same package size, so this is a non issue. However, the core crimp may heat up at higher current levels (this is what makes these interfaces melt and fail). Unlike crimps that come on aftermarket stuff, you can trust the original factory crimps. However, the science of connector current rating is based partly on the cross-section of the copper to wick away heat generated by the contact resistance. If I was doing this, I would extract the terminals with wire "a lot smaller" than what you want, pry open the crimps and insert your larger wire there. Then crimp the best you can and solder. You want enough solder to flow into the strands and terminal, but not enough to wick down to the insulation crimp, which would make the interface brittle. Normally the terminals can be extracted with a small pick tool.

 

[Fordum]

Well, there will be a slight voltage drop even over that short distance but it would be unnoticeable at any rational current level.
But it should be fused for the 14 gage wire.
I assume that you are using the 10 gage for less voltage drop instead of current handling capablites.

But, there might be a way to get the bigger wire hooked directly to the box. There should be larger wires in some circuits, so the connectors exist. You might find some in a junkyard with the larger wires already attached.

Instead of a fuse block like you have, you might have better luck with an aftermarket fuse block.
There are some nice ones out there.
Also, don't forget the relay option. You can use the smaller wire to control a relay that has larger wire direct from the battery to run heavy loads with less voltage drop.

 

[nsxxtreme]

I think your creating more work for yourself then you need to. I would ditch the fuse box idea. I would just buy an inline fuse holder that is about 6 inches from the battery post. Go to www.the12volt.com I believe they have a wire guage calculator depending on the current and length of wire you intend to use.

 

[nutt7]

If I was doing this, I would extract the terminals with wire "a lot smaller" than what you want, pry open the crimps and insert your larger wire there. Then crimp the best you can and solder. You want enough solder to flow into the strands and terminal, but not enough to wick down to the insulation crimp, which would make the interface brittle. Normally the terminals can be extracted with a small pick tool.

I will try to pry open some of the smaller ones...it seemed they might not have enough metal to grab the wire...we will see. I also plan on soldering connections.

But, there might be a way to get the bigger wire hooked directly to the box. There should be larger wires in some circuits, so the connectors exist. You might find some in a junkyard with the larger wires already attached.

Instead of a fuse block like you have, you might have better luck with an aftermarket fuse block.
There are some nice ones out there.
Also, don't forget the relay option. You can use the smaller wire to control a relay that has larger wire direct from the battery to run heavy loads with less voltage drop.

I looked today...the relays in this box have what seems to be a unique connector (I need larger relay wires, not fuse wires). I spent a couple hours looking in all types of vehicles and I couldn't find many compatible terminals with a wire over 14ga in size. I snagged a few though. I might try punching a hole in a couple other connectors so the plastic tab will engage them, but I doubt that will work.

I think your creating more work for yourself then you need to. I would ditch the fuse box idea. I would just buy an inline fuse holder that is about 6 inches from the battery post. Go to www.the12volt.com I believe they have a wire guage calculator depending on the current and length of wire you intend to use.

I really want to keep this box since I will be running a few circuits out of it (e-fans, power to firewall, headlight mod, a couple more later) and eliminating a fusible link or two. This box has standard fuses, maxi fuses, circuit breakers (maxi style), and bosch type relays. It should keep everything nice and centralized. It will mount nicely to the fender well too.

 

[coloradoblazers]

I looked today...the relays in this box have what seems to be a unique connector

What do the connectors look like?

I found an aftermarket VEC that I am going to use for my K5 and it took some google-fu, but I was able to track down connectors, terminals, etc from a few companies on the web.

Here are the connectors I needed for my app, perhaps they are similar to what you need? http://www.cci-products.com/VECconnectors.html

If not, here are some links I found when chasing my connectors down:
http://www.davisbus.com/C2 Accessory Manual/18_C2 Multiplex Connectors.pdf

http://www.agdirectusa.com/index.ph...150-16-pin-modular-plug-kit-package-of-1.html

http://www.mouser.com/Connectors/Automotive-Connectors/_/N-1ehb5?Keyword=ford&FS=True

If you can find out who supplies Ford with the connectors, then you can see if you can track them down (a dealer might even have the part number in their wiring schematics.)

NSX is right, you are creating alot of work for yourself, but in the end if it is worth it to you, then I think you are on the right path.

HTH

 

[nutt7]

I've searched and searched but can only find one type, and it's the wrong one. It is damn near impossible to open up one of the connectors to add a new wire too, unless I crimped the wire to the insulation crimp and soldered the rest, but I am not sure if that's a proper way to do it.

 

[Stomis]

Running a 14gauge wire in a 10gauge circuit is just about the same damn thing as having a fusible link. Except obviously wire doesnt have the necessary jacket for the weak spot to safely burn up and break connection.

 

[Blue85]

Running a 14gauge wire in a 10gauge circuit is just about the same damn thing as having a fusible link. Except obviously wire doesnt have the necessary jacket for the weak spot to safely burn up and break connection.

Not necessarily. If the fuse is sized for the 14AWG section, everything is safe. Having most of the run out of 10AWG will keep the voltage drop minimized. Fine for something like your low-beams. Not sufficient for a rack of off-road lights or a pair of big electric fans. Factory installations can have as much as 15A though 14AWG.

 

[Mcsjr454]

I know this isn't an answer to your question, however I thought it should be of note in the conversation. In the past I have done such projects as you are doing now, with some good results, and some bad ones as well. Since I have switched to my new mentality of building it right the first time, I now use painless pre labeled, prewired kits on all efi applications, and painless 18 circuit ato fuse center for all carbed and off roading projects.

It makes life easier during installation, and you will have far fewer wiring incidents down the road. I know the pricing seems to be on the high side, but after you take the plunge as I have, you will quickly find the cost no longer optional.

Wow I just reread that and it sounds like I am a spokes person for painless. I am not affiliated with them in any way shape or form, I just like to give credit where credit is due.

 

[nutt7]

I know this isn't an answer to your question, however I thought it should be of note in the conversation. In the past I have done such projects as you are doing now, with some good results, and some bad ones as well. Since I have switched to my new mentality of building it right the first time, I now use painless pre labeled, prewired kits on all efi applications, and painless 18 circuit ato fuse center for all carbed and off roading projects.

It makes life easier during installation, and you will have far fewer wiring incidents down the road. I know the pricing seems to be on the high side, but after you take the plunge as I have, you will quickly find the cost no longer optional.

Wow I just reread that and it sounds like I am a spokes person for painless. I am not affiliated with them in any way shape or form, I just like to give credit where credit is due.

I appreciate your advice, but I am still going to try it this way (for now). It's kind of fun, in an annoying way.