My layout was on fire!

[nomad]

If power is measured in watts, why are throttles and dcc controllers rated at how many amps they put out? Shouldn't it be watts?

Loren

[TCWORLD]

The voltage output is constant, so there is no need to put it in Watts.

[nomad]

Thanks.

Loren

[BR60103]

It depends on what you're concerned with. Amps is the load and you can add them up. You can buy an ammeter but I've never seen a watt-meter (maybe on the outside of the house!).
The load on your circuit is constant in watts (allowing for losses). Toy train transformers are rated in watts; Lionel used to rate loads in watts (so many for loco, lighted car, coal loader), possibly on the assumption that trans would be run full out.
In Britain, wire is rated by amps. A given wire will carry n amps no matter what the voltage. (Applies also to fuses.) 5 amps at 12 V is 60 watts which is 1/2 amp at 120 volts (and 1/4 amp at 240V).
Have I confused myself enough already?

[sgtcarl1]

Been there, done that! (wrench and battery.) Only with me it is always wrench and fender of vehicle being worked on.

[Sumpter250]

yeah, a typical car battery can deliver 100+ Amps "starting current". It won't do it for very long, but yes, long enough to weld a wrench to whatever.

[nomad]

You can also fry the radio and meter in a taxi. I found out the hard way. :oops:

Loren

[nkp_174]

This hasn't been mention...so...

voltage is the ability of electricity to jump...analogous to the height of a waterfall. If you've ever seen a bed sheet or towel spark...that is a buildup of thousands of volts but spark has very little amperage.

Amperage is the quantity of charge moving...analogous to the size of a river. (note that the word "current" is used both to describe the flow of electricity and the flow of water)

Because amperage is the quantity...it is what requires larger wires...not the voltage. If you think about this, you'll realize that wiring for DCC involves house wiring even though only 1/10th the power is being used. That is because the amperage can be the same...even though the voltage is 1/10th the size.

The square of the current multiplied by the resistance is how much heat will be given off at any point in a circuit. Copper is great because of its low resistance...and hence it can handle more current without getting fried than aluminum or steel. In the words of one of my former professors, we in the US have the luxury of using 110V instead of 220V due to our ability to use more copper in our homes. 220V has a greater ability to jump out and grab you...but doesn't need as large of wires (as much metal).

If you had a small enough saw, you could actually make the gaps in your rail so short that the electricity would jump despite the gap. Or, if you raise the voltage sufficiently, it would jump with your current gaps.

As a footnote...if you understand the fundamental equations for electricity, you also understand the fundamental equations for fluid mechanics and mass transfer...one of the cooler aspects of science!