advice on fusible link to maxi fuse- what amperages

[boboli]

I found a nice 8 post Maxi fuse holder in a dodge handicap van so i decided to replace all the fusible links on my convertible and add a circuit for an electric fan. I got it all running and driving... for a while.
In the heat of the day, with all the accessories going, the car died. I checked the maxi fuses, but missed the blown 1 that controls the ignition switch / fuse #1 fusebox.After a long, hot wait for a tow, replaced the fuse and the car starts and runs again.
I tried to make a safe guess on what fuses to use based on the guide to wire amperage i found here. I had a 20 amp Maxi fuse for the ignition switch/ fuse #1, but maybe it is too small of an amperage. I obviously don't want a fire but would a 30 amp be OK. I think the 20 blew just from too much draw from all the accessories. The fusible link was not a problem when i removed it, just wanted to tidy up the wiring (maybe not the best idea in the middle of the summer). The fusible link was an 18 ga that then went to 12 ga wire to the ignition switch and fuse.
Advice on what a fusible link equates to in a maxi fuse size would be appreciated as I don't want my other fuses to be under sized as well.
Thanks

 

[jrichker]

Fuse links come with a current rating just like fuses. A clue as to what current they are designed for is to look at the size wire they protect.

Choose the fuse according to the wire size.

Wire size current table:
18 gauge wire = 5-8 amps
16 gauge wire = 10-12 amps
14 gauge wire = 15-17 amps
12 gauge wire = 20-25 amps
10 gauge wire = 30-40 amps
8 gauge wire = 50-60 amps.

Fusible link colors
Link Gauge Color
20 Gauge Blue
18 Gauge Brown or Red
16 Gauge Black or Orange
14 Gauge Green
12 Gauge Gray


Keep in mind that the wire size in the chart is for the circuit itself, not the size of the fuse link. The packages of fuse link repair material you can get at the auto parts stores also will have a current rating on them.

See Ford Fuel Injection How To Solder Like a Pro for some excellent tips of soldering wires for best electrical performance.

Aircraft type circuit breakers are designed for low voltage DC applications and would be an excellent choice to replace fuse links. They come as a push/pull to reset button, and range from 1.5 amps to 60 amps and higher.

See Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co. or http://www.wicksaircraft.com/catalogDetails.php or Home for circuit breakers and other items.

There is a store local to Orlando that does electronic surplus and has all kinds of circuit breakers. See index That's where I get most of my wiring supplies. There may be a similar type store in your area.

Diagrams courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 86-95 5.0 Mustang wiring Mustang FAQ - Engine Information Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 94-95 5.0 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/94-95_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[HISSIN50]

It's not apples to apples but if you wanna kinda see if things seem like they're in the ballpark, here's the underhood fusebox for a 94-95 Mustang GT. Note that some of the SN systems are more substantial, so larger gauge wire might have been used since it supplies a larger draw. The SN fuses would reflect this, but a same-size fuse used on an aero fox might not properly protect a give wire/circuit rating. In other words, don't assume the wiring gauges are the same in both cars and that if a given fuse is ok for a SN circuit, it's ok for an aero fox circuit.

Image:Mustang9495UnderhoodFuses.gif - Mustang-Tech

 

[boboli]

Jrichker- thanks for the info. I had seen that and thought that using a 20 amp fuse would actually be too much for the circuit. When it blew the fuse, it made me worry that maybe there is something wrong in the circuit.

Hissin50- That info does help. I also found info on another brand's site ( minimopar.com if someone wants to look at the info) about converting fusible links to maxi's and it is comparable to the fusing in the sn fuse box.

My biggest worry is to set fire to the wiring. In the diagram provided by Jrichker, the ignition switch / fuse #1 had a 20 ga fusible link going to a 12 ga wire. I figured that meant only 10ish amps would be going through those wires. To confuse me even more, the maxi fuse box I got out of the dodge van had much higher ratings on the wires it had in it. The hydraulic system for the wheel chair ramp had 10 ga wire and the fuse was labelled 60 amps.
I think I should be safe with a 30 amp fuse, but if any one disagrees, speak freely please

 

[jrichker]

Single 12 gauge wire = 20-25 amps for the fuse.

I looked over a considerable number of web sites and a fuse link to amperage rating was not to be found on any of them. If anyone comes across such a chart, please let me know.