when to make + and - wires larger ?

[blazer2007]

I was wondering when to increase the size or wire when you are connecting several pos. and neg. wires into one wire. Say you have 5 toggle switches at 18 gauge and you wire all 5 pos. wires together and connect them to one wire to run to your fuse box,is there a formula to tell what you you should increase the one wire too.and the same for the neg. side

[kwmech]

Ohms law. I cannot recall the formula at the moment, but I'm sure it can be found on Google

[toolboxchev]

a larger wire will allow more juice to be pushed through it. It will also have less resistance. You will also have to use automotive grade or even better marine grade.

Look to the ASTM standards.

[Bigdav160]

There are charts on the internet that will tell you the amperage a particular wire size can carry at a certain voltage.

You can think of resistance (measured in ohms) and amperage (the amount of electricity) as opposites on a teeter-totter. If resistance goes down amperage goes up and vise versa.

Lets pretend that each of your 5 circuits is carrying 10 amps of current. That means you need a wire (and fuse/terminals) large enough to handle 50 amps. When wired in parallel, the resistance goes down so the current goes up.

to add, in DC electricity all the electricity travels through the + and the - so the wire gauge should be consistent on both sides of the circuit.

[blazer2007]

thank you