electric fan wiring caught on fire

[GetBoost]

I have dual flex a lite fans wired with the control box. The other day the wiring that goes from the battery to the control port B caught on fire. I have it wired with 12 gauge wiring running through a 30fuse and then into the control box. When I opened the hood the fuse was not blown, but the wiring around it was cheery red and smoking. I need some advise how to wire this a safer way. Im wondering if that inline fuse is the problem, because that is where it started at, and the fuse did not blow. Should I just get like 8 gauge wiring and go straight from the battery to the control box?
thanks,
John

 

[s383mmber1]

Do you mean the Fuse box?

 

[MDCmotorsports]

Pictures or diagram on how you have it wired would help.

IIRC 30 amp on the fans is a little high.

 

[GetBoost]

No I have an inline fuse relay in the wiring between the battery and the electric fan control box. I believe 30 amp was what the fan called for, but I will double check. I will try to get pictures up tomorrow.

 

[NashMan]

what type of fuse you got in there sounds like slow blow to me

but all i can remmber is you have to run 12 guage wire at lest do nto tie both fans in to one lead

but tellyou give me an idea on how your setup is then i cna not help you

 

[figgie]

cherry red on 12 gauge?

Are you 100% positive that it was 12 gauge wire? I never had any issues with 12 gauge wire into the FAL 220?

 

[NashMan]

cherry red on 12 gauge?

Are you 100% positive that it was 12 gauge wire? I never had any issues with 12 gauge wire into the FAL 220?

i am thinking he taped them both togetter and used 12 to 12 then to 12 = fire or melted fuse not eghough to blow the fuse but eghough heat to melt



really the best way to do it is use 2 relay's 25 amp one should do but ti all about the draw that the fans pull

 

[GetBoost]

okay I tried to take some pictures so hopefully this helps. I dont want to drive it to I get this fixed

 

[jetjock]

Do you know how many amps you'd have to pull through 12 awg in open air to make it cherry red? And the wires in the photo look pretty good for having done it .

 

[GetBoost]

Well this happened at work so I had to rewire it so I could make it home. Its wired the same way before except I had the relay on the battery side, with the blue wire connected on the other side of the relay. If you look at the battery near the black wire you can see where the wire was so hot it cut through the battery plastic.

 

[jetjock]

Ah, I see now. Well, the little part of it I can see seems wired right. Sloppy but right. I'd have that fuse closer to the battery but I'm splitting hairs.

12 awg will easily handle 30 amps in open air so the fuse will open before the wiring burns. Did the entire wire get hot or just the connection near the battery? Any high resistance connection will get hot so be sure all those crimps are well done. If the everything is wired right that's the only reason I can see for your symptom. It also explains why the fuse didn't open.

 

[GetBoost]

okay the fuse was right next to the battery before, and it is the problem I think. When I opened the hood the fans were still going which means the fuse didnt blow, but the fuse holder (the black part) was cherry red and smoking. The wiring started to burn but it was never red or anything, just smoking a little. After it cooled down I opened the fuse holder to check the fuse and it was pretty much ash. it just crumbled when I touched it.

 

[jetjock]

Bad connection in the cheapie fuse holder. Not enough clamping pressure on the fuse blade. Typical of those things. It explains why the fuse didn't open because excessive current wasn't flowing through it. Get better stuff. I see several things in those photos that could cause grief down the road. Too many crimps, the faston quick disconnect, ect. In a high current low voltage circuit resistance is the enemy. You must have good integrity at every connection. Keep them to a minumum and solder after crimping. Use a better quality fuse holder or a fusible link instead.

 

[GetBoost]

okay thanks jj. I had a feeling it was the relay causing the problems. where would be a good place to get one? Obviously places like advance auto and pep boys arent the place to go because this is all they had. Would running one 12 or 10 gauge wire from the battery to the control box be safer then running with this fuse?

 

[jetjock]

The fuseholder was the problem, not the relay. If it was the relay or a problem in the circuit it would've blown the fuse. I suppose you could've gotten a mislabled fuse but what are the odds? That the fuse burned but did not blow indicates a bad connection at that point.

The wiring, connections, and every device in the entire circuit needs to have enough ampacity to do the job. If the fans draw more than 30 amps or cycle often 10 awg would give an added measure but you'd have to use it throughout. Of course, the relay must also have enough capacity but since I'm assuming it came with the fans it must.

The fuse must be sized to protect the wiring, not the fans. 12 awg should be fine. Since you have a new fuseholder the problem may never repeat itself or if it does it'll be at the next weakest connection point.

 

[GetBoost]

thanks for the information, I understand it more now. I will redo the wiring a little neater now that Im not rushed to get out of work. I'll start looking for a different type of fuse holder also. Hopefully it doesnt happen again, but I feel better knowing what caused it. I've been thinking about going back to the clutch fan here lately so that might still be an option.

 

[jetjock]

As I said, resistance in a high current low voltage circuit is bad news. It's like trying to suck hard through a straw while pinching it. In a circuit with such a restiction the electrons start bumping into each other and cause heat. It's no different than rubbing your hands together.

It's localized heat though, only at the restriction. That's not the same as trying to suck too much through a straw that has no restrictions but is simply too small to begin with. In that case the wire will get hot along it's entire length. Any fuse in the circuit will also get hot and open. That yours didn't is a sign you had high resistance at only one point.

 

[NashMan]

that and some frans will draw more then they say they will flex alight is know to this

ps butt connect's = getto wireing

i have wired one of these up befor useing 2 relays and it worked like a charm and it's the the proper way of doing it

1 relay per fan i used 25 amp relay's as well

if you want i can make you diagram


oh yae if you ever use butt connect's or sleav's all ways use soder and flux and torch or small mini torch push both wire in the sleav tell they tuch each other do not leav a air gap at all this will cause heat build up on high draw systems then use shink wrap after words

 

[GetBoost]

yes I could use a diagram nash, thanks! So what the best way of wiring it without the butt connectors? Is soldering both wires together without any connector the way to go? Ive never soldered before

 

[jetjock]

Well, something like AMP PIDG terminals and an AMP ProCrimper are a far cry frm the crap bought at hardware and auto stores and the toy crimpers most people use. Fwiw crimped connectors are employed all over aircrat while soldering is not permitted in other than avionics. Also, a properly selected and terminated crimped connection is gas tight. It won't corrode internally and will always have equal to or greater ampacity than the wiring it's connecting. It all comes down to using the right stuff. The relay for each fan is a good call though.