1. A HUGE switch may be able to handle the current.
2. You have to have that switch's wiring into and out of the cab.
3. These wires have to carry all the current.
4. If one of the wires shorts.... the ciruit's toast.
a. Safer not to run high current wiring into/out of the cab.
b. It's a cleaner circuit.
c. It's easeir to lay out.
d. Using all the same relays means you have parts if one relay fails.
e. The relays are cheap and standard.
6. Take at look at the attached schematic:
There is only a need for seven (7) wires to come into the cab and into the console. This lets you put all the relays, fuses, etc. in a convient and centeral area under the hood. It's easier accessed an MUCH safer.
The MASTER swtich in the schematic can also be used as the basis of the kill switch...
A kill switch should enable or disable electric devices by also eabling or disabling relays. [img]images/graemlins/grin.gif[/img]