Does fuse 8 really need to be 15A ?

[duncsuk]

Having routed new wiring from the second battery to connect to fuses 6,7 and 8, I see that the wire out of fuse 8 (cold side) is small diameter (couple of amps?) and I assume therefore it connects to a relay which in turn feeds the power to the cigar sockets & mirrors.
1. If there is indeed a relay, is that fed from the main battery/alternator circuit ?
2. If so, even with the new wiring, using the cigar sockets without the engine running will run down the MAIN battery ?
3. No need to worry about feeding a high-amperage wire to the 'cold' side of fuse 8 ?

Am I right ? Does this make sense ?

TIA ...