ATV Electrical ?'s

[LMITOUT]

I thought that resistance changing with temperature was basic enough for the crowd and help expand from the standard thinking box, but then again I am an engineer and tend to go off on tangents every once in a while...

[Roofer]

In my field of work, I have heard some really funny things from engineers and architects. They usually like to think rather than do, if that makes any sense. It's easier on paper than it is the real world. No offense LMITOUT.

Example, one engineer stated that we needed 14 bolts down a 2x10 ledger board, 1 1/2" apart.........ummmm, it's only 9 1/4" wide, how can that even happen.

We had two 2x10 ledgers bolted together, and he thought we were using 2 1/2" screws........well, that wouldn't even make it through the 2x10's, let alone hold it up.

On top of this he wanted $250 for his "thinking". And yes, he had a blue print.

Sorry to stray from the topic, but just thought I would share.

[sparkydm]

I thought that resistance changing with temperature was basic enough for the crowd and help expand from the standard thinking box, but then again I am an engineer and tend to go off on tangents every once in a while...

I feel that the heating/resistance issue is important to understand with regards to wire size. For example, let's say your adding a sprayer system to your atv. You add a circuit to run the pump. It's a large pump and you use too small a gauge wire to start with, and you over-fuse it. That skinny wire gets hot from over-amping it. Higher heat means more resistance. More resistance means more current. More current means even more heat. More heat, more resistance. See where I'm headed? Hopefully the fuse rating is low enough that it blows before the wire melts.

[sparkydm]

By the way LMTOUT, there's a saying in the trades that says there's a point in every job when you must shoot the engineer and get on with production

[LMITOUT]

That's often the case when people are intimidated by someone else's smarts or level of authority. They always try to prove the engineer wrong, and in some cases they are, but it seems to be the case more often then not that the engineer has to repeatedly prove him or herself to be correct and mostly because the other person doesn't have a complete understanding of the entire scope of the project or problem and just see it for face value. It goes all the way down the ladder though...the new guy on the job always thinks they're smarter than their supervisor and so on. Someone always believes they're smarter than their boss, and it's the same with engineers who disagree with their engineering manager. Kids always think they're smarter than their parents too! Just the way the world works!

Oh well, I've come to expect it at this point. Like water off a duck's back....

Engineers have a saying too: Arguing with an engineer is a lot like wrestling in the mud with a pig.....after a while you figure out that he's enjoying it.

[BobT]

Originally Posted By: LMITOUT

I thought that resistance changing with temperature was basic enough for the crowd and help expand from the standard thinking box, but then again I am an engineer and tend to go off on tangents every once in a while...

I feel that the heating/resistance issue is important to understand with regards to wire size. For example, let's say your adding a sprayer system to your atv. You add a circuit to run the pump. It's a large pump and you use too small a gauge wire to start with, and you over-fuse it. That skinny wire gets hot from over-amping it. Higher heat means more resistance. More resistance means more current. More current means even more heat. More heat, more resistance. See where I'm headed? Hopefully the fuse rating is low enough that it blows before the wire melts.

Actually, if the resistance is increasing the current should be decreasing, should it not? Ohm's law.

The thing is, in your analogy you used undersized wire and oversized OCPD. Both of these conditions lead to the ability to over-current the circuit and this will overheat it to breakdown.

Bob