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Old 26-02-2016, 19:59   #1
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Best ( or preferred ) location for Bus Bars both +ive & -ive

Hi all,

I'm seeking advise on the best possible location for Bus Bars?

I've rebuilt my boats Distribution panel as the old one was showing signs of heavy corrosion (as was the wiring at it). This has meant relocating the new distribution panel thus also the new bus bars.

The old distribution panel was next to the stairs leading down into the cabin, thus, it was a highly susceptible area to seawater splashing. I've now relocated the new distribution panel higher up and more inside the cabin to protect it was being highly susceptible to salt water splashes.

My question is, should the bus bars be closer to the distribution panel or closer to the battery area (approx 1.5m or 4.5ft from batteries to distribution panel)

Bus bars closer to battery area require multiple 1.5m runs of wire up to distribution panel from bus bar.
Bus bars closer to distribution panel only require battery cable run to panel.

or is there a better option.

The new distribution panel I've made out of left over perspex. I've also included a new 6 gang switch, added an extra 3 gang switch (to separate Nav equipment from accessories such as lights) and a separate auto bilge. I've also added 2x 12-volt cigarette adaptors for USB charging and 12V items. Lastly, I've also built in the Volvo diesel Tacho and switching.

The new distribution panel

The old distribution panel area, (To the RIGHT of the bottom step into the cabin). NOT the best place for it, as water spray comes over, rain falls directly down to it and wet weather clothing drips on it.

Under the tool box to the right is the dual battery compartment, which is approx 1.5m / 4.5ft from the new distribution panel.

I'm just trying to figure out best or preferred placement for the bus bar (-ive) and a spare (+ive)

Cheers, Peter

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Old 27-02-2016, 11:30   #2
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Re: Best ( or preferred ) location for Bus Bars both +ive & -ive

Distribution bars can be used for various purposes and to give you a good answer you should say what specifically the purpose of the distribution bus is for. If you are powering the new panel you would just need one (fused at the battery) lead to the panel. If you also want to send power to the windlass, and to something else not powered from the circuit breaker panel, or, to take the charging input from the alternator or solar panels it would be best to put a heavier duty bus near the battery (with fuses) and the one fused wire to the panel.

If you need to distribute power to various lights in the cabin from the panel circuit breaker, you would want the bus to be near as possible to the place where you need to split the wires out to both sides of the boat, overheads, or cockpit, or wherever. Usually that is done near a panel but doesn't have to be. You do need to make sure that your circuit breaker is sized for the smallest gauge wire on that bus though, or, you have to put a fuse on the smaller wire at the bus.

If you are talking about DC negative cables/wires then those can be at the battery with a shorter big cable from the battery to the bus, or to wherever you can save the most wire away from the battery with a longer big cable from the battery to the bus.

Wherever you put a bus, make sure it is reasonably easy to get to to check wiring/terminals/screws/nuts and to put on new or take off old wires. Sometimes, in fact, you may decide to put a bus someplace just because of this even if it takes more wire sometimes. You need to be able to get a wrench and/or screwdriver readily to work on the bus. And label every single wire on the positive and negative buses. Every time I think I will just remember I don't, or the next guy won't know for sure. Just as important for positive and negative to trace problems easily.

You may be thinking of something different than this so give more info for more feedback. Your panel, and bilge switches, etc. looks to be DC only. If you are talking AC you need to be considerate of making sure it is someplace you can make sure you won't touch it under maintenance situations (a cover, etc.).

Let us know more specifics if this doesn't cover it. It's a good question. I am taking great care to place the distribution buses for my large battery rewire as it makes a big difference in access and ability to run the cables. And to make it all tidy and easy to understand later or while doing the work. I actually screwed down one big bus that I am going to move after looking at a couple of issues (no room for the big cables to have nice runs and interference with other gear nearby).

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Old 27-02-2016, 13:19   #3
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Re: Best ( or preferred ) location for Bus Bars both +ive & -ive

Both. ex-maggie gave a more detailed answer.

The trick is to put them where you NEED then, first, then if necessary, where you want them for convenience.

It's all part of the overall design.
Stu Jackson
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Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
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Old 28-02-2016, 23:58   #4
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Re: Best ( or preferred ) location for Bus Bars both +ive & -ive

Originally Posted by Stu Jackson View Post
Both. ex-maggie gave a more detailed answer.

The trick is to put them where you NEED then, first, then if necessary, where you want them for convenience.

It's all part of the overall design.
Thanks, exMaggieDrum and Stu Jackson,

Really good replies, luckily for me the previous owner labelled every (every) wire at the old distribution panel and before the wires 'disappeared' into the boat cavity/walls roof etc and then at the equipment

Unfortunately, his fantastic labelling is not continued to the quality of installation/wiring choice/ganging' of irrelevant wires e.g. (AWG 16 running from battery to power the old distribution panel, hence, explains why the whole panel flickered and dimmed when 4 our of 6 switches were used) or his (running the VHF radio, Bilge, GPS Plotter and 12V cigarette off 1 (one) switch) :-(

I'm waiting for my tinned marine cable to arrive, but I'll locate the positive bus at the distribution panel and the negative bus at another location that's close to the battery.
I'm running separate wires for +ive and -ive so the wires do not need to be 'together' per say.
However, before I start I'll probably sit down, look at the run of the soon to be installed cable, look over my diagram and then make a final decision.

Cheers, Pete
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