Wiring upgrade case study

[DanielI]

So I’ve got a wiring diagram which I will post soon, but I realize that how the battery selector switch is wired is not my main question (which I took to be the reason people were asking for a wiring diagram).

Looking back at the picture of the panel wiring are there any red flags I should be concerned about that I need to replace? I know about the AC circuit separation and it is not on the top of my priority list because I do not use AC power at all currently. I was concerned whether the use of one circuit breaker for multiple circuits is an issue. I also have certain several circuits where multiple wires are coming into a single crimp connector going to the switch. For the one I was working on, I wanted to move it to a terminal block, but is there a reason to move them all, or is that mainly aesthetic?

If so what’s the best way to attach the terminal block to the fiberglass behind the panel?

[DanielI]

So, here is the wiring diagram. The red wires are the way the system is set up now, the black wires are what I'm thinking of doing about the 1-2-Both-Off switch. For whatever reason, this seems to be the subject people are most interested in. I'm more interested in the subject of my previous post (namely, whether and how to add a terminal block).


But, for those of you more interested in battery switches, here is my thinking: I would like a dedicated start battery (yes, I know that is not necessary). I was also thinking I would like my house loads to run off the LOAD output on my MPPT. It seems to me that requires two selector switches, one for START and one for HOUSE, but the latter one is running a smaller load, and therefor should be fine with a 20A SPDT switch, rather than a full battery selector switch.


So the idea is I remove the RED wires on the diagram, and add the BLUE wires. The original 1-2-Both-Off switch is now a battery selector for the starter. This switch would normally be left on "1", which is the START battery. The other switch would be HOUSE-COMBINE-OFF, where COMBINE means connect the house to whatever the engine is using. Any comments on this arrangement?

[DanielI]

Originally Posted by Cheechako

Hey Stu, fiberglass isn't resistant to battery acid? Aren't there large fiberglass battery boxes sold out there? Or am I having a brain fart?

Yes, I was concerned about Stu's concern, but now I found this post from MaineSail:

https://forums.sailboatowners.com/th...05/post-914404

I've started to learn who on CF needs to be listened to, and who can be safely ignored, but when Stu Jackson and MaineSail disagree, then people like myself are in a real quandary. Luckily, it doesn't seem to happen too often!

[DanielI]

Okay, reviving this thread. Maybe this means I’m actually making progress, maybe not. A man can dream.

I have a tank water pump and a lake water pump both on the same circuit. The wire goes first to the tank pump, and then tees off to the lake pump. I want to separate these into two circuits. I’ve run a red (+) back to the panel for the lake pump. Do I need to run separate lines for the (-), or can I use the old tee connection?

[JoeRobertJr]

Daniel,
Things to consider when deciding whether to continue sharing the existing ground wire:
1. Condition of the wire. Is it old enough or of a poor type that it should be replaced?
2. Voltage drop. Add the current of both pumps together. Measure the round trip distance from panel to pumps. Use a wire sizing chart to compare your existing ground wire size against the recommended size given the current and wiring length. If the wiring chart says your ground wire is good enough for one pump, but not both, then perhaps run a second ground wire in parallel, or replace with one wire from panel to tee that is large enough to hand both loads.

[CharlieJ]

@DanielI # 34: Reviewing this thread, it appears that you are trying to rewire your Catalina correctly and in compliance with Standards. For ease of troubleshooting in the future and to alleviate possible voltage drop in the two circuits and overloading the common B- return and because it is the correct way, run a separate B- return for the lake pump.
BTW, the tank water pump and the lake pump need to have OCPD sized to meet the manufacturers' instructions to protect against circuit failure during locked rotor condition.

[Statistical]

Originally Posted by DanielI

Okay, reviving this thread. Maybe this means I’m actually making progress, maybe not. A man can dream.

I have a tank water pump and a lake water pump both on the same circuit. The wire goes first to the tank pump, and then tees off to the lake pump. I want to separate these into two circuits. I’ve run a red (+) back to the panel for the lake pump. Do I need to run separate lines for the (-), or can I use the old tee connection?

The proper thing would be separate negatives back to the negative busbar. It may seem a small thing and honestly it is but wiring ends up a rats nest of cables not from one big decision but a hundred small ones.

As for safety and voltage drop that would depend on if the two pumps will ever be used at the same time. If they can then all wiring in the circuit (both + & -) should be sized for the combined amperage.

[DanielI]

Thanks. You are both correct, my question was how to do it RIGHT, now how to make it work. I pulled a second wire, so now both pumps run back to the panel.

[DanielI]

Originally Posted by CharlieJ

BTW, the tank water pump and the lake pump need to have OCPD sized to meet the manufacturers' instructions to protect against circuit failure during locked rotor condition.

I googled OCPD, and came up with obsessive-compulsive personality disorder. Took me a minute to realize you weren’t just making a joke.

Both pumps were installed by PO, so if he didn’t size them right, I guess that’s a project in my future.

[CharlieJ]

LMAO
It appears that you arrived at Over Current Protection Device; i.e., fuse or circuit breaker.