Breakers vs. Fuses

Breakers are not that expensive. Just order a bunch from aircraft spruce, right around $6 each. Way cleaner to install than a fuse panel, allow resetting when an intermettent problem pops up, and proves when an electrical failure is permanent. We had a window motor that would blow the fuse intermittently, and almost stopped us from starting a stage. $5 breaker would have made life much easier.

My new car will have a full panel of breakers.

I used the switch type marine breakers, two functions with one thing, a switch and current protection!

I used fuses for things that did not matter so much and breakers for things I might want to reset mid stage and see what tripped.

---

In the long run reality always wins.

Breakers have a delay as they are tripped by the heat generated from the current going through them. A motor for example might draw 3A but it will spike on startup to say 6A. A fuse in this instance would have to be a 10A or it would trip as soon as the motor starts. With a breaker you could use a 5A and it would not trip until it sustains amperage over 5A. So a breaker can give you more protection in some instances. Most fuses in cars are fast blow. An electronic device such as your ecu, diff control etc would be best to have on a fast blow fuse. Typically someone will reset a breaker without second thought and hope it stays closed. Fuses lend themself to a person looking for why it blew. But most people with limited electrical experiance will replace it and sometimes with a larger fuse... Look for the smoke boys!

its all about application. I like the new fuses that have a small LED built into them. If they blow the LED will turn on (its a very high resistance and the voltage drop across it will not hurt anything). Keith, Hardy's car has them.. Great use of them.

---

Intercom and electronics dude. www.zerodegreec.ca

Quote
zerodegreec
Look for the smoke boys!

It's what I always tell the enginerds at work;

Don't tell me I can't run XX amps through (insert gauge of wire from 12 to 18). The smoke will let me know pretty quick whether I can or not

Quote
HiTempguy

Quote
zerodegreec
Look for the smoke boys!

It's what I always tell the enginerds at work;

Don't tell me I can't run XX amps through (insert gauge of wire from 12 to 18). The smoke will let me know pretty quick whether I can or not

Haha depending on the application that's sorta true, but if you run anything over 5 feet you'll start to get a fairly significant voltage drop.

Quote
fliz
Wouldn't it have been easier to just throw a 20A fuse into the slot than have to replace a breaker? 20A fuse could be swapped out on stage.

To Steve's point about accuracy, I thought I remember somebody saying that a repeatedly tripped breaker could allow a much higher current, and increase the possibility of wiring shorts.

No Chad, the breakers I have are push button, not the little spade fuse thingies. I just pushed it back on, the swap was at a later time. No need to swap breakers if their speced right, I just didnt do it right for that circuit.





Edited 1 time(s). Last edit at 05/16/2012 07:46AM by Cosworth.

How many of you own or built yourself a shunt to test what the actual amp draw is on the circuit(s) that you are putting fuses into? Willing to bet people are running with fuses WAY over sized for the actual load of the circuit. We went through the drag truck a couple years ago and you would be amazed at how many circuits had a 15A fuse and ran only 2A at full load.

---

Intercom and electronics dude. www.zerodegreec.ca

Quote
zerodegreec
How many of you own or built yourself a shunt to test what the actual amp draw is on the circuit(s) that you are putting fuses into? Willing to bet people are running with fuses WAY over sized for the actual load of the circuit. We went through the drag truck a couple years ago and you would be amazed at how many circuits had a 15A fuse and ran only 2A at full load.

I just steal my really low amp AC/DC amp clamps from work. SO COOL

But sooo expensive.

Quote
zeerodegreec
How many of you own or built yourself a shunt to test what the actual amp draw is on the circuit(s) that you are putting fuses into?

I attempted to calcumalate the amperage per circuit - but I also tried to separate devices and put on separate circuits such that if they went down it would only affect 1 critical component at a time.

I have the same push button breakers as Casworth.

You can buy one for $10
http://www.deltecco.com/MKA-DC.html

Or make your own for virtually nothing. Instructions and a video of how to make your own.
http://www.reuk.co.uk/Make-a-Shunt-Resistor.htm




Calculating your load is ok but choosing your fuse sizes based on actual readings is the way to go. Considering the cost of buying a shunt (assuming you have a meter anyway) is nothing. Plus you can use it for diagnosing high amp draw devices like your fuel pump etc.

---

Intercom and electronics dude. www.zerodegreec.ca

Quote
derek
I used the switch type marine breakers, two functions with one thing, a switch and current protection!

Ditto....nice and simple. All sorts of used mil-spec ones on ebay for cheap. I got 25+ breakers for under $100.



Edited 1 time(s). Last edit at 05/18/2012 02:36PM by urr.

after doing an ebay search i found lots for 5 amp and up, what're you guys using for the smaller 2 amp circuits?

---

what could go wrong?

That shunt video is so easy and understandable its super cool !

However, to get exactly 1 mv resistance per amp - I think the sizing of the 8" wire would be needed?

The length of the heavy gauge wire is not important. Here is how I made mine:

I stripped a long piece of of 8ga at say 12". I then went in about an inch and soldered a small ga wire (wrap it around the wire and soldered it).

I then hooked up a known load (a load small enough that I measured earlier with my meter. it was a small motor that drew 2.3A or something like that).

Once I had the load going through the 8ga wire I put my meter on mv. One lead on the small ga wire I soldered on and found the other point on the wire that gave me the equivlent of 2.3mv.

Soldered a second small ga wire at that point and tested again (sure enough I had to move it slightly due to the resistance of the solder and wire). But lets face it, a fraction of an amp differance is not going to be detrimental for 99.9% of the jobs it is used for.

Have fun.

---

Intercom and electronics dude. www.zerodegreec.ca



Edited 1 time(s). Last edit at 05/18/2012 08:57PM by zerodegreec.

http://www.aircraftspruce.com/catalog/elpages/pbcircuitbrkr3.php

They have 1,2,3,4,5,7,10,15,20,25,30 amp Tyco breakers for around $6-7 each new.