My brother was the one mainly worried about it. I told him, there are a lot of other things to worry about on this turd...
CK5
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'86 Jimmy 4in Lift, 40’s, tons, 8.1 Swap- 700r4 said PNNNNN
- Thread starter GWeakland620
- Start date
This is not a dedicated trail rig, but does trailer to the destination usually. I am currently in the planning phase of doing a 52/56" spring swap, and getting back to being more road worthy.
My brother was the one mainly worried about it. I told him, there are a lot of other things to worry about on this turd...
It's a philosophical difference. Personally I prefer to avoid switching the ground leg, because that means that the rest of the wires are always energized, and so the potential for starting a fire when they break is always present. Or even worse, if the ground side shorts, you might have the fan turn itself on randomly.
If you switch the hot side than the circuit spends all of its downtime dead, and the shorting potential on either leg is only present when the switch is flipped. Which, for a wheeling rig that sits in the back yard, has gotta be less than 1% of the time. Does it matter? No, it's mostly a question of style. But I wanted to present the flip side of the coin. I don't think it's worth worrying about, particularly if you already have a list of worries.
Whatever matches the thermostat you plan to use is the easiest way to go.
The current (power) flow is identical, regardless of which side you switch. The energy is not "spent," it's an endless loop flowing back to the battery. It's like trying to say that the caboose goes slower than the passenger car. It's nonsense, they're all coupled together and the whole train (circuit) goes the same speed.
Unless you're trying to split off power to a second circuit from the return leg, then you can have different amounts of current flow between the 2 circuits. But for a single circuit it can't matter which side you switch (current-wise).
Well I will say this. When my buddy and I originally wired up the fans, we had it with switched power. So it was a lot less work to add the relay and fuse, and keep it the way it was.
I would say I'm shocked, shocked to hear this, but unfortunately I've seen a lot of unfused wiring mods on vehicles.
On my Blazer I found a wire plugged into one of the fuse holders (in place of the fuse) running straight to the 12V junction on the firewall, feeding power backwards into the fuse block!
On a side note, I haven't had any headlights since I unplugged that one.
I had my buddy come over that night to help me with the wiring, as I do not get along well with electrical work. Needless to say, he threw a lot together to wheel for the weekend and I was not aware of that (this is also the same guy that disconnected my ground for the headlights and did not tell me...).I would say I'm shocked, shocked to hear this, but unfortunately I've seen a lot of unfused wiring mods on vehicles.
Last night I spent an hour on the phone with my brother, and he shared much knowledge on electrical. I felt confident enough afterwards to attempt it myself, and I am now proud of myself. So no more letting someone else do the work without double checking it.
For the sake of not taking all your time while visiting, I think I'll leave the hood shut.....I'll double check it for you.
If energy s not spent than why do we have to keep recharging the battery with the alternator?
I agree that flow is present on both sides of the circuit, but the electrical energy (pressure) is being converted to movement (fans) or illumination.
When you connect things in series, the amount of available energy drops for each item.
I am not an electrical engineer by any means, but I have had switches get hot while in the positive side of the circuit, and stay cool when moved to the ground side. There are plenty of times that things have to be switched on the hot side (starter) because they ground through the case. It definitely is ok, you just need to be sure to use a switch rated for the amperage and voltage.
This is simple.. current follows the path of least resistance, the body is a larger ground path vs the switch.. if you switch on the body side it doesn't generate the heat because there is little to nothing stopping the electrons flowing to their target, the other way you present a switch and wire etc which has a much higher ohm/resistance value thus creating a more resistive path for the current to flow. Resistance generates heat..
Both of your statements are true, but I'm talking about current flow. Energy is a static concept, it's like a weight hanging over your head. What's driving the fan is the release of energy, which we call power. Power is the rate of energy release. People often abuse these terms (I even did so in my 3yr old example to keep things dirt simple), but they are not the same thing. DC circuits operate kinda like water flowing in a hose. The voltage of a circuit is the pressure of the water, how hard it's pushing on the hose. The power is the total rate of water flow, how many buckets you can fill in a minute. The current, which is what I was talking about, is the speed of the water flowing through the pipe. This is what makes wires hot, when you draw more current (which is a function of power and voltage) through the wire than they can safely handle. This is how wires fail and also how electrical fires start.
My comment was that, regardless of where you place the switch, in a single circuit, the current is equal no matter where you put the switch. You can put the switch on the positive leg, the negative leg, or somewhere in Kazakhstan, the current will always be the same. Going back to the hose example, if you have more water flowing into the hose than you have flowing out of it, you will have a serious problem very quickly. Wires don't "store" electrons (at least, not until you get into AC and RF circuits), they always flow through them and back to the positive side of the battery. If you split the wire and drive some second circuit, then you will have a balance of current flowing through each circuit (and there are a few simple laws governing that if you wanna get into circuit theory). But moving a switch from one side to the other does not affect the flow rate any more than moving the hose valve from the end of the hose to the middle. It's still the same hose driven by the same water pressure, the location of the switch does not change that. It just changes how much of the hose is always pressurized vs. only being pressurized when the valve is open.
If your switch magically stopped overheating when you moved it from one leg to the other, my best guess is that you had a crummy connection (high resistance) that was fixed when you rearranged the circuit. Because the math doesn't work out that way if location is the only thing you changed.
Yes, Greg, I did just say "math," get over it. 
V/I*R
I am referring, of course, to the rig at the far left.
I keep telling him it's seriously tail-heavy, but he won't listen to me because I use this magical thing I call "math." Evidently he doesn't believe in such deductive wizardry.
Says the guy who can only count one tree in Kansas, it looks like an entire row of trees under that REA line......
Martin
The high resistance / bad connection thing makes sense. It has been a very long time since I had any issues with hot temps in any of my wiring jobs...
Likely was a product of being too careless with my wiring jobs when I was younger.
Seems as though we are debating personal preference here. The only reason that I even came back to comment was your statement of energy not being spent, when you were actually talking about current flow. Had me confused.
Likely was a product of being too careless with my wiring jobs when I was younger.
Seems as though we are debating personal preference here. The only reason that I even came back to comment was your statement of energy not being spent, when you were actually talking about current flow. Had me confused.
I'm pretty sure Greg isn't reading any electrical theory talk.
It's not that complicated.....
It's not that complicated.....
Yeah, where the switch goes is definitely a preference. And you'll find both methods used in factory applications. Sometimes it's easier to switch one, sometimes the other.
