All about switches; post, throw, terminal Q's

I am looking at these carling switches because they go with my ARB switches. i see Waytek offers several different types, trying to figure out what all these acronyms mean in english and what they mean to the layperson (ME)

http://order.waytekwire.com/scategory2/M50/260/200/Carling%20Contura%20Rocker%20Switch/Switches/

SPST - single post, single throw?
SPDT- single post, double throw?
SPTT - single post, thriple throw?
DPST - double post, single throw?
DPDT - double post, double throw?

1. What exactly does "post" mean when referring to a switch or toggle?

2. What do they mean by "throw"? is that the stages of the switch, like "on" and "off"? why would you need a triple throw?

3. Are there any advantages to SP or DP?

4. do i need anything over a 20 AMP to run my fan, fuel pump, fuel pump switch, aux lights?

switches

this will help.your fuel gauge switch is a doubble pole doubble throw

Thanks for the diagram oleguy.

if i am understanding this correctly, i can use single pole single throw for most of my switching needs?

Elec Fan: SPST
Fuel pump: SPST
Fuel selector switch: DPDT
Aux lights: SPST

single pole single throw is just off-on.you gotit

Looks like oleguy74 picture covers it pretty well.
- Number of Poles is the number of positive wires connected to
the switch. Basically the number of independent circuits switched.
- Number of Throws is the number of switch positions that
complete the circuit. So Single Throw (ST) is On-Off. Double
Throw (DT) can be On1-On2 or On1-Off-On2.

In your examples if each switch is controlling a single electrical
circuit, that means Single Pole (SP). For any device that is
On-Off then ST is sufficient, however if for example your lighting
or fan has High/Low positions then a DT could be used with one
position for Low and one for High.

For the Amp draws you'll need to lookup the stats on the motors
(fan, fuel pump), I don't have any general experience on what
range of power those typically suck up. Also I have no idea
what the fuel pump switch is. Lighting is typically specified in
Watts, which is (Amps * Volts). So for instance a 100W light
is going to pull ~8Amps @ 12V (100W/12V=8.33A), in that case
you could wire two 100W bulbs through a 20A circuit.


good luck & have fun! danny