LED Strip Light addition -- battery power?

RandACampin wrote:

tenbear wrote:

RandACampin wrote:
Current is the same in the entire circuit...therefore a fuse anywhere in the circuit will afford the same protection.

"The current is the same in the entire circuit."

That is true in normal operation, but if a short develops in the wire, the current will be very high between the battery and the short. The fuse will only protect the circuit if it is located between the short and the battery. Shorts can happen anywhere that the wire rubs against something, especially the metal frame.

And the fuse will protect it no matter where it is in the circuit. Car fuse panels are nowhere near the battery, RV fuse blocks are often at the other end of the trailer from the battery on the tongue.

Ohms law means that no matter where the short is the current is the same throughout the entire circuit whether the short is at or near the battery the entire conductor (circuit) will see the same rise in current.

1. Every single modern-ish car not designed by the British (poke) has a main battery fuse mounted as close to the battery as possible, usually the main fuse block next to it. Example:



The wire leading to this is rated for the total load of the vehicle's electrical system except for the starter (which is generally unprotected). After this, each sub-circuit has a fuse rated for its total load as close to the main battery fuse as possible. This is because any length of wire prior to the fuse it unprotected.

2. Ohm's law specifically states: "the current through a conductor between two points is directly proportional to the potential difference across the two points."

BETWEEN TWO POINTS. So, from point A to B, current will be constant. If the fuse is between A and B, then current generally (fuses/relays can fail) is regulated by the fuse. If the fuse is not between A and B, the current can and will reach whatever it wants until the wire itself becomes a fuse (generally resulting in burning of some sort). A circuit is not a wire. A circuit is the flow of electrons from positive to negative (DC). If the ground is 1/3 of the way down the wire, and the resistance is low enough, the circuit is 1/3 of the wire, plus whatever the shortest path back to the battery is. Anything powered on after that is a different circuit with the same source.

Don't believe me? An experiment (which would be at your own risk) would be to take a fuse holder, connect one end to the positive, and some other point in the wire (stripped bare) before the fuse and touch it to the negative. I'd suggest a good burn ointment, but I know how electricity works. :D