1. You need a way to turn off power to the 802 because the radio
draws power even when turned off at the radio
2. A 30-amp toggle switch isn't easy to find and is usually expensive.
3. Since 30-amp circuit breakers are relatively cheap
and very easy to find, there is the tendency to hook the radio up to a CB on the panel.
4. This is usually a bad idea because the wiring
to most CB panels
isn't heavy enough to properly power the radio, hence Icom's recommendation that the radio be connected "directly to the battery
The simplest but most expensive way is to use one of the Blue Sea remote
switches. You can control it remotely with a simple momentary toggle switch. Costs about $130 in the US. It's a mechanical solution without the problems of the CH solid-state switch.
The cheapest way is to buy a high-current automotive type relay (Panasonic makes one rated at 70 amps). I use one in my refrigerator
and the replacement from Digi-key was under $8. This has a coil that draws about 200ma when the radio is turned on. It can be installed in place of the CH and probably use all the same wiring
If you can't find it, send me a private message and I'll see if I can find the complete part description.