I have just upgraded my trunk wire from my second battery to the "trunk" ha ha ie load compartnmment of the RRC, from a 12 and 8 AWG combined to a 4AWG as I have now put a compressor there.

The wire goes from the second battery , is very tightly stuffed into a "maxi" blade fuse ( 30 amp currently but 40 spare and up to 60 are available) about 20CM from the battery and then through the firewall to across the floor to behind the rear wheelarch where I have placed one of those gold Doof Doof wire distrubutors with a 8AWG to a 70 amp relay for the compressor and finer wires for the Engel and merit plugs for the camp lights.( the gold doof doof distributor has been there for years)

Is the fuse the best solution considering voltage drop for the circuit , seeing my plans include a compressor which may draw 30-40 amps intermittently. I currently have a 70 LPM compressor which draws about 18?amps.

If you recommmend a circuit breaker , what amps? and what is available to fit 4AWG wire. The wire is the multi strand Jaycar nice flexible stuff.

Regards Philip A