beaterX project thread

[Matt D.]

To be clear, the boost just happened to go this high, my goal is to keep it right around 30. It was a good test of the fuel system though, so I am happy with it.
Just happened to go that high... Yeah, right! ;) Are you worried about the stock wiring being the weak point with such a large fuse in there now?

[Murlo26]

That is the idea of many fuses, to protect wiring, not protect devices. Basically anti fire device :)

[Kracka]

Basically anti fire device :)
Yes, but only if they're properly sized for the gauge of wire they're being used on. Going from a 20A to a 30A doesn't sound like that big of an increase, but it's still 50%.

[Murlo26]

Well what gauge wire is the fuse on? 14 awg maybe? 14 is good for 15 amps, 12 awg for 20 amps...and so on.

I am an electrical engineer, done plenty of fuse sizing in my day.

[Kracka]

So say it is 12 awg since the factory fuse was 20A, wouldn't running a 30A fuse on it become a fire hazard?

[Murlo26]

Possibly yes, depending on the wire rating. Some are rated for higher temperatures. What I quoted was the 75 degree C wire rating. There is also 60 degree and 90 degree and really high temp stuff that you can get away with a lot more.

75c is the norm typically though at least for industrial use, I am guessing auto is similar.

It honestly all depends on what kind of current he is actually drawing. If I knew that it would be easy to tell you. And it also depends on the type of fuse. There is an entire icky thing called fuseology...basically you have fuse curves that depending on current levels and length of time at those levels the fuse will be fine or blow. It gets messy.

[scheides]

Yea I would put in a 25A fuse but all I had was 30. I don't expect it to be a fire hazard as it's not going to continually run at the full 30a. The kit itself includes an upgraded 40a fuse so anyone that has installed one has likely run into this same problem.

If it ever is a problem, I make sure to carry a fire extinguisher at all times in the trunk.

[Murlo26]

^I am going to start carrying one myself. I think it makes sense with the level of modification I have.

[scheides]

FWIW I had done probably 10+ pulls w/o blowing the stock fuse so I'm guessing it's running right around 20A. The weird thing is that it blew right as I was getting on it, not like at the top of 4th gear or something (after a looooong pull at high amperage).

[Kracka]

Probably due to a quick spike as it turned on I bet. Like turning on a light, the initial surge is always greater than constant draw.