I'm believing that someone here can answer this for me. Why do they make those blade fuses in 3 different sizes? The trailer wire for the stop light got smashed against the hitch frame and shorted the fuse on my 2000 Chevy C2500 pickup. The fuse that shorted was a 30 amp maxi fuse. I'm just wondering why they put 30 amp fuses in the truck that are 3 sizes-maxi, regular and mini. I am thinking if it takes 31 amps to melt the fuse material, what difference does it make whether it is a maxi, regular or mini. I understand the need for 40 amp and higher in the maxi configuration and the mini to conserve space. I just don't understand a need for a 30 amp in all three sizes. Thank you in advance for your opinions.
- Thread starter kito169
- Start date
Steve@Advance
Well-known Member
I don't think there is a logical answer for it either. Several factors, cost being the most important. The engineers go with the most cost effective product available that will get the job done.
There is also a "service factor" (I guess that would be the proper term), the maxi fuses would be used on circuits that carry heavy current for prolonged periods where heat can build. For the minor branch circuits, they may have a 30 amp mini fuse, but would not normally carry any where near capacity load, but are oversized to prevent incidental, nuisance failures (like the trailer light circuit).
Unlike high voltage circuits in a residence or industrial application where there are industry wide standards, there are no real rules when it comes to low voltage or automotive applications. If it works, and meets the DOT or where ever it's made, then it's pretty much up to the manufacturer to put what they think will work out there, and hope they don't get bit by warranty or recalls.
There is also a "service factor" (I guess that would be the proper term), the maxi fuses would be used on circuits that carry heavy current for prolonged periods where heat can build. For the minor branch circuits, they may have a 30 amp mini fuse, but would not normally carry any where near capacity load, but are oversized to prevent incidental, nuisance failures (like the trailer light circuit).
Unlike high voltage circuits in a residence or industrial application where there are industry wide standards, there are no real rules when it comes to low voltage or automotive applications. If it works, and meets the DOT or where ever it's made, then it's pretty much up to the manufacturer to put what they think will work out there, and hope they don't get bit by warranty or recalls.
MarkB_MI
Well-known Member
- Location
- Motown USA
Are all three sizes of 30 amp fuse in the same fuse block? Or are they in different blocks? If they're in different fuse blocks, then I'd say it's just an artifact of re-using parts from different vehicles, or coming from different design houses.
If they're all in the same block, the use of different sizes must be intentional. My guess is they use the maxi size when they need to crimp heavy gauge wires to the fuse terminals, and the smaller sizes to save space. It could have to do with whether the load is expected to be continuous; a brake light would need to support continuous loads while the vehicle is sitting at a light, for example; that would require heavy gauge wire. An intermittent accessory, such as power door locks, wouldn't need heavy gauge wire, even though the momentary current is high.
If they're all in the same block, the use of different sizes must be intentional. My guess is they use the maxi size when they need to crimp heavy gauge wires to the fuse terminals, and the smaller sizes to save space. It could have to do with whether the load is expected to be continuous; a brake light would need to support continuous loads while the vehicle is sitting at a light, for example; that would require heavy gauge wire. An intermittent accessory, such as power door locks, wouldn't need heavy gauge wire, even though the momentary current is high.
Jim in Ma.
Well-known Member
Seems to me, I read somewhere that the Maxi fuse is a slow blow and a mini is a fast blow regular is normal blow. With that set up you can't put the wrong one in a circuit.
MarkB_MI
Well-known Member
- Location
- Motown USA
> Seems to me, I read somewhere that the Maxi fuse is a slow blow and a mini is a fast blow regular is normal blow.
Good call. Per the Littlefuse site:
Micro2 blows in .75-120 secs @ 135% rated current
Mini 32V blows in .75-600 secs @ 135% rated current
Maxi 32V blows 60-1800 secs @135% rated current
Littlefuse automotive blade fuses
Good call. Per the Littlefuse site:
Micro2 blows in .75-120 secs @ 135% rated current
Mini 32V blows in .75-600 secs @ 135% rated current
Maxi 32V blows 60-1800 secs @135% rated current
Littlefuse automotive blade fuses
Ken Macfarlane
Well-known Member
Wait until you get a newer dodge and they have another bloody fuse format in multiple sizes that aren't hardly available anywhere.
Thank you to everyone who replied. I did not know about the time required for the fuse to blow. The 30 amp maxi fuse is under the hood in a fuse box with other maxi's that range from 40 to 60 amps. The mini fuses are on the side of the dash where the door opens. I really enjoy this site because of the wealth of knowledge here. Thank you all again. Rick
jimg.allentown
Well-known Member
I'll take a guess here.
I suspect that the size of the "service panel" would have something to do with it.
The maxi fuses in the underhood panel range from 20 or 30 to 60 amps. So, the space and gauge of wire needed for the 60 amp fuses would require a larger panel to accommodate the wire and fuses.
The "regular" blade fuses would be replacements for the older round fuses.
The "mini" fuses seem to be better suited to the smaller panels inside the vehicle that have many more circuits. Saves a lot of space.
I also notice that you usually do not see all 3 sizes in the same vehicle.
I suspect that the size of the "service panel" would have something to do with it.
The maxi fuses in the underhood panel range from 20 or 30 to 60 amps. So, the space and gauge of wire needed for the 60 amp fuses would require a larger panel to accommodate the wire and fuses.
The "regular" blade fuses would be replacements for the older round fuses.
The "mini" fuses seem to be better suited to the smaller panels inside the vehicle that have many more circuits. Saves a lot of space.
I also notice that you usually do not see all 3 sizes in the same vehicle.
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