Im trying to figure out some wiring (again). I have my sub-panel how I likes it, and I just upgraded the main feed lines from 8 AWG to 4 AWG so I feel very happy feeding the sub-panel more amps that my alternator could possibly supply.
So I got my sub
Woo! I can’t tell you how long this has been coming. So now I have a decision to make for wiring. I did the math and I need 20 amps of capacity which means 8 AWG wire (at the distances involved) which I have, though my 8 awg lugs aren’t my favorites (too big a hole). Anyway, here is the situation. I have 4 paths to get the power to the sub.
1. Run it straight from the Circuit breaker (100A) that feeds the sub panel and then fuse at the source.
Pros - simple
cons - the whole point of the sub-panel was to consolidate electrical and reduce extra wiring all over.
2. Run it off the sub-panel from the A circuit, which is battery hot straight out (fuse on sub-panel)
Pros - ideal, the panel can handle 30A/circuit, though only 100A total. Granted the whole thing is on a 100A breaker so Im not worried about melting the panel.
Cons - I would have to rewire some other things on the circuit as all slots are full.
3. Run it into A Circuit then into a relay triggered by the ignition, its a small Zhong Tong mini NO 30A relay, so it can handle the current but the wiring in and out is 12 AWG. I could size up from the output to 8 but I feel like that’s a bad idea.
Pros - no sneak drain when the power is off
Cons - wiring is far from ideal and I don’t know how I feel about running 20 amps through these little relays.
4. I could run it into B circuit which is run entirely off a NO 120 amp relay ignition triggered.
Pros - no sneak drains when the power is off, open circuit
Cons - puts stress on the B circuit which isn’t the more powerful of the 2 circuits. It’s on a 60A breaker and the 8 AWG connecting the circuits only really allows for 50 or so amps and I already have about 40 on there. I want to upgrade the wiring to 4 AWG but I don’t have the needed lugs. I can do a mix of 4/6 which would let me run up to the 60 limit of the breaker no sweat. there would be 60 fused amps drawn on B if I put it here. more heat through the 120A realy.
The sub and my stereo have a remote trigger so it can power off when the stereo does so I technically don’t NEED to have its supply ign triggered. But it would give me some peace of mind knowing there wouldn’t be a sneak drain when in the boonies. I don’t know how that would affect the sub long term though to be hard cycling each startup.
Thoughts?
EDIT: I upgraded the wire to 6/4 so now the B circuit can happily handle the limit of the breaker. I’m still going to wire it hot off of A I think though.