Hello,

Something that has confused me a bit, and now is dictating some components I select, is how a components max current rating compares to the voltage going through it. An example I am dealing with:

http://www.mouser.com/pdfdocs/AmphenolSine_ATPFlyer0911.pdf
These connectors are rated for 25 Amps, and some sufficiently high voltage rating.

What happens if I put 40 Amps as 3.3 Volts through them? How about 20 Amps at 480 Volt AC? It seems like the power between 40 Amps at 3.3 Volts is WAY lower than 20 Amps at 480 Volts AC. And isn't power loss where the heat comes from? Is there a formula or curve for this?

What about cable itself. I'm familiar with house wire gauges 14 being 15A and 12 being 20A. But can I put 40 amps of 3.3V through 14 gauge wire? If not, how come?

Specifically I am speccing out connectors, cables, switches and such and trying to make sure I am appropriately sizing them for the high amperage. The system runs on 12V for anywhere with current that is above mA levels.

 

Voltage rating:
Things like connectors and wires have a voltage rating which is governed by the insulation they use. Exceeding the voltage rating can risk damaging the insulation. This does not depend on the current flowing in the connector/wire.
A current flowing in a wire or through a connector dissipates power depending on the resistance of the wire or connector according to the formula P = R * I^2. That power will cause heating and, ultimately, damage.

Current rating:
The permissible current in a wire depends where you put it:
Out in open air allows a higher current as the heat can escape from the wire.
In a conduit, especially if bundled with other wires, the current allowed is lower as the heat cannot escape, particularly for wires in the middle of the bundle.
None of this is affected by the voltage on the connector or wire.

Note: The above is not the general case. Things like relay contacts and transistors have a more complicated relationship between maximum voltage and current.

 

The current will be determined by the thickness of the conductor pins and wires, the voltage will be determined by the insulation around each conductor and the casing.

 

The current will be determined by the thickness of the conductor pins and wires, the voltage will be determined by the insulation around each conductor and the casing.

And the amount of power will be determined by the whole assembly's heat dissipation capabilities.
EDIT: Which is also related to its internal impedance.