BajaRunner

NOT IN MY 4RUNNER LUCKILY.

My buddies '73 Cj-5. We wired up a CB a few weeks ago. According to online documents, they said to run the positive wire directly to the battery along with the supplied inline fuse.

Anyways, he was driving, with the CB off, and saw smoke coming from underneath his hood. When he opened it, the power wire of the CB which was 14 gauge was smoldering. There is one other aux wire coming from the battery which powers something else (not sure what). It was not on fire... just the CB wire.

What could have caused this? Im thinking the inline fuse was too far back from the battery terminal (a good 5 feet). But, the fuse did not blow.

It does run above the engine, but, not any closer than several other wires (a good 8 inches away from the valve covers).

Bob_98SR5

did you guys check the inline fuse? you made a good observation too. i suspect taht the fuse was burned out but carrying the current. that current could have burnt the 14 gauge wire up which caused it to smoke.
had that inline fuse been within 12 inches (always recommended) of the battery pos terminal, only that short section wouldve burnt. your friend or whomever installed it, did not follow good wiring procedure

L33T35T 4Runner

Yes, most likely that wire shorted out before the fuse and went up in smoke. as bob said ,you should always have the fuse within 12 inches of the battery, i like to do it as close as possible. within 4 inches normally. your friend is lucky it didnt go up in smoke inside his cab and burn down the truck

BajaRunner

Okay, sounds good. I will make sure to tell him.

Whats funny is his dad is a professional electrician. haha

He's too lazy to ask his dad anything anyways. :/

GSGALLANT

I agree with everybody on having the fuse close to battery, but that isn't the only issue here. Having the fuse far from the battery is only a problem if your wire gets grounded somewhere between the fuse and the battery. You need to check the wire insulation (if there's anything left of it) to see where it was shorting out.

surf4runner

what size fuse (amperage)?
if an intermitant short occured, it could have smoked the wire while still not blowing the fuse. especially look around where the CB is mounted.

was it OK for a few weeks? then smoke...

wrenchmonster

Did he remember to install a grommet at the firewall?

Bob_98SR5

good points. but i think its safe to assume that the cb was grounded near the cb itself because that is where the ground wire is coming from. doesnt make a whole lot of sense to run it back to the engine bay. is that what you mean?

4x4Lamm

Well, like others said, it was prob. a short between the battery and the fuse.

And on a side note, I always ground everything (except lighted switchs) all the way back to the battery.

Lamm

GSGALLANT

Sorry Bob. Poor choice of words on my part. I agree that the CB is likely grounded inside the cab. What I meant is: "...only a problem if your positive wire gets shorted somewhere between the fuse and the battery." Thanks.

BajaRunner

The ground is actually a good 4 feet away from the CB, because it was mounted up on the ceiling, well, on the roll bar. The ground has to go down to underneath the dash, which is a good 4-5 feet of wire.

Everything was wired in 16 gauge wire...not 14 as I had previously thought.

The fuse did not blow.

So just a random short in the positive line?

GSGALLANT

You should be able to squeeze about 12 amps through 16 guage wire at the length that you've run it. What size fuse did you have on the line? The max fuse size I would put on that particular setup is 10 amps (otherwise, your wire becomes your fuse). What side of the fuse was the wire melting? (between fuse and battery or between fuse and CB?)

Finally, did you guys use new wire or wire that was laying around the house or garage for some time? If it was older wire, and if the melting was localized in a small section, you could have had some broken strands of wire at that point. If you have broken strands of wire, you're essentially reducing the guage of the wire in that small area, which becomes an added resistance in your circuit, which in turn increases the total current going through your line and can cause the wire to heat up.

BajaRunner

The wire melted from the battery, all the way up to underneath the dash. It was a good 4 feet of melted wire. The fuse was way up near the CB. It was the stock inline fuse that came with the Cobra CB, so I would imagine they would use the correct fuse. Once again, it was not blown.

We re-did the wiring yesterday. We have an inline 15amp fuse that is mounted 5" from the battery.

The wire we used was brand new. I had just bought a 100ft spool. (too much).

I see a potential problem in my truck:

I have 8ga wire that was running to my aux fusebox. I installed a 30amp inline fuse 10" from the battery on the 8ga wire. The inline fuse only had 12ga wire, and the only way to get the existiing 8ga was to really spiral it around to fit into the butt connector. I think some of the wires broke off.

Is this a fire hazard?!?!

GSGALLANT

If you're left with a wire bundle the size of a twelve gauge wire where your 8 gauge wire goes into the butt connector, then I wouldn't worry about it. The trick is simply to make sure you've got enough wire strands carrying current so that the wire itself doesn't cause a large voltage drop (high resistance to current = high voltage drop = heat). If you were only able to squeeze 10 thin strands of your wire into the connector, and you were trying to put 30 amps through it, then you could have a problem.

4Hummer

The problem is you installed a perfectly good CB into a JEEP....... Like everything else JEEP related it will either break, fall off, leak, not work or catch fire/melt.

Had that CB been installed into a Toyota with the exact same setup I dought there would have ever been a problem.

Tanto

4chucker

FINALLY!!! someone with the right answer. dude, always put the fuse as close to the power source as possible.this protects the device,the wire and your health.

BajaRunner

Hhahah thats pretty funny

boogyman

actually, having the fuse close to the source doesn't really matter in low voltage/current applications like this. From the symtoms described (with the wire going before the fuse) it sounds like the fuse amperage was too high for the circuit/device. When that's the case, the wire burns out like a fuse before the fuse because it's the weaker part of the electrical link.
Russell

Granted, having the fuse close to the power source won't have any effect on the circuit itself, but it might reduce the risk of shorts for the person wiring up the circuit if they aren't taking time to wire everything properly.

4x4Lamm

I don't think so boogyman.

I really doubt the STOCK fuse that the CB company used was too high of an amp rating, In fact, I bet it was one amp.

Electricity is like water in pipes. If the battery is the pump and the wire is the pipe, the fuse is the shut-off valve. A break in the pipe between the pump and the shut-off valve cannot be shut off with the valve (fuse). This is why you put the fuse close to the source.

I'm not trying to be a jerk, but yotatech sort of has an anti-misinformation theme we are trying to enforce.

Lamm