Fuses are there to protect the circuits in your cab. If an over sized fuse is in place the circuit in the cab will burn up before the fuse if there is a problem. This means that you will be sacrificing the circuit to save the fuse. It is like putting a penny in an old fuse box in a house. The house will burn but the penny will not.
I got a funny story about that.
I used to work at Rat Shack in a slummy part of the city. The kind of customers we tended to get were lonely house wives trying to connect up their crappy VCR's (my co-worker got a lot of action from that). Lots of abused women trying to fix the computer their boyfriends smashed. People trying to use inducting cell phone antennas in place of proper full sized whip antennas. Lots of theft. Lots of dumpster divers (requiring us to take a sledge hammer to anything we threw out). That sort of thing. It was a pretty good neighborhood.
Anyhoo, this guy comes in and starts asking us a bunch of questions. Claims he's in the, "microwave repair business." I think he thought he could have us sell his surplus microwaves or some stupid ---Cleveland steamer---. This spans a course of several days, usually with him leaving with some small purchase, like a switch, a spool of wire, whatever.
One day, he starts bragging about how he's come across a dozen microwaves (this is right before trash day). On this day, I was trying to repair one of my toys. The fuse kept popping and I was futzing with the multimeter trying to locate the problem. As he's eyeing the toy, he made a comment that he didn't understand why fuses were necessary. I carefully explained it's to prevent the circuit from frying. Conversation proceeded to go something like this:
Idiot: It won't fry.
Savannah: What? Of course it would, that's why the fuses keep popping.
Idiot: No, trust me, it won't hurt anything.
Savannah: What? You're telling me to put in a bigger fuse?
Idiot: No, you don't even need to do that. Just wrap the fuse in aluminum foil and stick it back in.
Savannah: Aluminum foil? What the ---fudgesicle--- are you talking about?
Idiot: Just wrap it in foil.
Savannah: Where did you get this idea?
Idiot: Look, I know what I'm talking about, I found twelve microwaves today and half of just had a blown fuse. I put aluminum foil around the fuses, put them back and voila! I got a microwave I can sell!
Savannah: .... (a photograph of my face at this point might be appropriate. My co-worker said I looked like I was playing poker.)
Idiot: I sell lots of microwaves after I
fix them.
Savannah: What's the name of your business again?