I'm guessing there was a lot of advise given without fully understanding the application. The various wire sizes were obviously the previous owners whacked out idea - I doubt there was any rhyme or reason for the 10 gauge wire, or even the 12 gauge. I really doubt it had anything to do with the original installation or the current requirement for the pump. If the pump was fitted for 16 AWG wiring then I suspect that this minimal size was all that is necessary for all 3 wire connections (for normal round-trip length of wiring). The diagram didn't make any sense ... did that come with the pump packaging or was it from some other source. It seems to me that the pump is one of those models that has an internal float built into the housing, not a separate float switch. I never liked those for a sailboat hanging out in the water. I had one of those pieces of crap in my ski boat that lived on a trailer or a dock lift, but not on a sailboat.
Some key things that
@SailingFree44 should understand:
1. Based on Post #53 ... somethings not wired correctly.
2. Why is there a seacock on your bilge discharge? That doesn't make sense.
3. The wire selection is based on the amperage and the length of round trip run from the panel to the pump and back. Round trip is your red positive from the panel to the pump plus the negative from the pump to the negative buss (which is also probably at the panel).
4. "Critical" vs "Non-Critical" is the difference between the tolerance for 3% voltage drop (critical) and 10% voltage drop (non-critical). I suppose in this case it is subjective. It depends if you want your pump to run at full capacity or something less than full capacity. If you accept low capacity, you can use 16 AWG wiring for up to 50' of wire length round trip. If you want full capacity, then limit your wire length to 15' or switch to 14 AWG up to 20' or 12 AWG for up to 30'. Learn how to read the chart ... it tells you.
4a. Don't believe the stated capacity of the pump. It probably won't be close - so it's best to wire it for "critical" - 3% voltage drop limit.
5. The circuit breaker at the panel protects the
wire. If you want to protect the pump at no more than 5 amps then you can add a 5 or 10 amp in-line fuse ... but nobody does this for a bilge pump. We protect expensive electronics with fuses, but typically we select circuit breakers (or fuses) at the panel only to protect the wire that is feeding the loads. Typically, 16 AWG wiring can be protected with 15 amp circuit breaker (or fuse), unless it is an unusually long run.
6. I thought I read that you wired the automatic but by-passed the manual? Or was it the other way around? This doesn't make sense. Learn how a bilge pump is intended to operate. There are various ways that we wire them as well. I suppose the 3-position switch is most common. The automatic position is intended to run through the float switch when you are away from the boat. The manual position on the switch is intended to run the pump at will. I don't know why you would by-pass your manual switch position ... that just makes your pump in-operable on demand.
7. Follow the instructions from the installation manual that came with the pump. If it is not understandable, then I would question the pump ...
8. Just do a solid crimp connection and heat-shrink protection. Don't over-think it. You can use some di-electric grease for good measure, but don't solder. Keep the wires high and dry as you can at the connections.
