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Typical wiring to / from battery selector switch??

8K views 18 replies 9 participants last post by  pegasus1457 
#1 ·
Hi folks,

Just tracing out some wiring, as I don't think my DC feed from battery selector switch, to DC panel, is sized large enough. It looks to be about 14 ga, where most individual circuits are 14 - 16 ga.

I am trying to determine where all of the wires go , from the battery selector switch. This is a 30 ft, 30 year old sailboat.

Of course, I have 3 connections on the back of the switch: (swich is a make b4 break, off, 1, both, 2 type of switch.

1. battery 1 pos connection
- has battery cable and a small gauge wire that goes to DC panel voltmeter

2. battery 2 (2 batteries inb this bank) pos connection
- has battery cable and a small gauge wire that goes to DC panel voltmeter

3. common - have 1 red wire that goes to alternator
- have 1 red wire that goes to feed DC panel (believe to be too small guage)
- have another red wire, small gauge / style as feed to DC panel..........Where do you think it would go?????

Other than the common feeding the DC panel, and being connected to the alternator, for charging either bank, where would this other wire likely go??

Thanks in advance for the help!!!!
 
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#5 ·
Actually, the Bilge pump is wired from the DC panel, which gets shut off as well! Perhaps not smart, but it was like that when i bought the boat a couple of years ago.
My bilge was quite dirty / oily after years of neglect, and I did not want a permanently wired / auto bige pump, that would put out oily water.
I now have the bilge to a pretty clean state, so I could likely rethink this now.
However, I have a traditional stuffing box / hose in good repair, and close all 3 seacocks if I am going off the boat for more than an hour, etc, so, for me, I don't really see the need for a directly wired / auto bilge pump.

Back to the original question, where else could that other wire go, from the common battery switch post???

PS. Bill - my Iota 45 amp charger has been working well. Great recommendation, and great price as well.
 
#7 ·
The wire size from the disconnect switch to the panel will depend on how much power your are pulling when everything is on. Total up your amperage and the check that against the ABYC chart for the distance your are travelling. I would guess that if your panel is like mine, you likely will need 8ga or possibly 4ga.
 
#8 ·
ScottyT- no, it does not go to the charger. I put the new Iota charger in this spring. It goes connected to the AC panel, and then directly to one of the batteries in bank 2.

The wire may even have been an old bilge pump, for example, that is no longer there / in use. Who knows. Whereever it goes, it is getting DC voltage, that is not wired through the panel, and it looks like original wiring.

Patrick - thanks for the advice on the wiring chart. I will calculate things before replacing. I still may ot go with the "proper" size though, as I will not be having all of my DC lights, water, bilge, pumps, etc on at once, and even a jump from 14 Ga to 10 Ga would be a huge improvement. Getting a larger wire over there may be very difficult!
 
#10 ·
Therapy - you are right , of course.. it is better to make it perfect. However, it has worked for 30 years with the current wiring, and is still floating. If I improve things by changing the feed from 14 ga to 10 or 8 ga, for example, it will ceratinly be better than it has been (for 30 years).
re: emergency, yes some things like running lights, steaming light, bilge pump and electronics could all be used at once. But I doubt that I would also "need" to turn on the water pressure pump, anchor light (assuming we are moving), all five or six cabin lights, etc, during an emergency as well. So I think that some common sense can be used in determining wire size.
 
#14 ·
You know..........

You are absolutely correct.

I should not have used a cursury blanket statement like that.

Let us know what that last pesky red wire went to.

A friend of mine bought an old Catalina and when we disconected one of the batt hot wires the shower sump pump came on. :eek:

I did not figure that one out as he sold the boat a few months later.
 
#16 ·
Therapy - I didn't mean to sound like an a$$. Juts meant that, alothough I usually do try to do things right, any improvemnt is still better than it has been for 30 years (ie from 14 ga to 10 ga, etc)
Of course, I am putting more electrical demands on it than it had 30 years ago, when new!


Well, the other red wire (positive lead from Common post of battery switch) went to a small unfused distributions block, which feeds the VHF radio, an who knows what else. I will be trying to trace out the other wires at some point. Or at least disconnectting them, and seeing what doesn't work. Most items are accounted for on the DC panel, and now I know how the VHF is powered.

Next I will be looking at how big of a DC feed to use to replace the other red wire ( the main feed for the DC panel).

Thanks to everyone for their help. I have worked each of the last 2 winters on more important projects. Now, I would say that cleaning up / replacing alot of the wiring will be this winter's project. There are alot of butt connectors used to lengthen wire runs, and I am afraid to pull too hard on wires to trace them as I don't want to pull them apart. Will replace any of those wires when I have a chance.
 
#18 ·
Pegasus - thanks for the reply. You are correct, that one red wire does go to the alternator. However, the one that I could not account for went to a non-fused distributionb block for things like my VHF, stereo, etc, that were not wired to the fused / toggle switched DC panel. These devices all have in-line fuses. I guess they wanted these devices to come on, as soon as the battery switch was turned on, without having to flip on certain panel toggle switches.
 
#19 ·
Pegasus - thanks for the reply. You are correct, that one red wire does go to the alternator. However, the one that I could not account for went to a non-fused distribution block for things like my VHF, stereo, etc, that were not wired to the fused / toggle switched DC panel. These devices all have in-line fuses. I guess they wanted these devices to come on, as soon as the battery switch was turned on, without having to flip on certain panel toggle switches.
More likely the DC panel ran out of breakers before they ran out of boat bucks :D.
 
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