Bus Bars

Tug · Posted: Fri Oct 08, 2010 10:40 am Post subject: Bus Bars

I am going to install a few bus bars to help reduce the birds nest around my batteries. What i intend to do is locate one of the bus bars behind the Port bulkhead. The question is this......i am going to attach the aux.power point/fishfinder/bilge pump etc. to the pos/neg. bus bars and then run a #8 Marine wire to the battery...each of the items have there own in-line fuse of different amperage. If i will be merging these wires and only running one wire to the battery terminal what size in-line fuse do i have to use. Thanks Tug

Captains Cat · Posted: Fri Oct 08, 2010 10:43 am Post subject:

Both CD's that I have had have one big (like 50A) breaker (not a fuse) back by the battery on the positive lead that runs forward to the bus bar for accessories. You don't need to fuse the negative side.

Charlie

BrentB · Posted: Fri Oct 08, 2010 11:04 am Post subject:

I plan to install a Power post
http://bluesea.com/category/9/38/productline/195

Wandering Sagebrush · Posted: Fri Oct 08, 2010 11:20 am Post subject: Re: Bus Bars

Captains Cat · Posted: Fri Oct 08, 2010 11:23 am Post subject: Re: Bus Bars

Mike... · Posted: Fri Oct 08, 2010 11:37 am Post subject:

BrentB · Posted: Fri Oct 08, 2010 11:47 am Post subject:

Tug · Posted: Fri Oct 08, 2010 5:38 pm Post subject:

Electricity Question

.Am i right to assume i need one common bar bus for negative wires and another bus bar for positive wires or is one side of the bus bar negative and the other side of the bus bar positive. Any suggestions on the bus bars amperage size and can anyone recommend what type of breaker to put between the bus bar and the battery.Tug

Mike... · Posted: Fri Oct 08, 2010 6:19 pm Post subject:

Tug · Posted: Fri Oct 08, 2010 8:22 pm Post subject:

Confusing...( to me )..maybe i am not explaining what i mean...i have for example ..power point outlet plus fishfinder plus bilge pump switch installed on the Port helm bulkhead. I want to installed POS/NEG Bus on the inside of the Port helm bulkhead.The pos/wire from these devices go to pos/bus and the neg/wires from these devices go to the neg/bus. Than i will run a #8 wire from the pos/post of the pos/bus to the pos/post on the battery. I will do the same for the neg/wire/bus. Here is what gets me, all of these devices have a different amp inline fuse for safety, how do i determine what amperage to use for the in line fuse for the single #8 wire that i will run from the pos/bus to the pos/post on the battery.Doesn't the in line fuse installed on the # 8 wire have to be compatable with all three devices **** i posted some new pictures in my album,some of my battery wires and one picture of an unknown battery connecter, any ideas what it is.****Tug

Captains Cat · Posted: Fri Oct 08, 2010 8:43 pm Post subject:

Tug, no fuse or breaker in the #8 negative wire to the battery. Put a large BREAKER, at least 30 Amps, in the positive line. Not difficult.

Tug · Posted: Fri Oct 08, 2010 8:52 pm Post subject:

Charlie thank you for clearing it up for me, will make that a winter project. Should be fun. Tug

Tim & Dave Kinghorn · Posted: Mon Oct 11, 2010 4:31 pm Post subject: Wire Size and Circuit Protection

Tug,

I assume the distance from the battery to the port bulkhead is at least 15 feet. If so, you will have a total run from the battery to the distribution panel and back to the battery of some 30 feet.

If you run 30 feet of #8 (15' positive and 15' negative), the maximum usable amps for a 3% voltage drop would be a total of 15 amps at the distribution panel; and for a 10% drop voltage drop, it would be 50 amps. A 10% drop from a battery at 12.5V would deliver about 11.25V at your distribution panel (plus additional drops in the loops off the distribution panel).

I would suggest going with a #6 wire. This would give you a usable 25 amps with only a 3% voltage drop and 60 amps at a 10% drop.

I would most certainly put circuit protection as close to the battery as possible to protect the run to the distribution panel. A conservative over-current protection for #8 wire would be 50 amps (ampacity). For #6, it could be 80 amps. I personally like the Blue Sea circuit breakers. You don't have to worry about a spare fuse, and you can get the one with a switch on it. You will find that fuse holder and the fuse will run close enough to the circuit breaker cost to make it a better choice. As others have pointed out, you only need to protect the positive (red) side.

I have used the distribution panel you are using. It can hold 12 circuits. Each of the circuits are then fused to protect that leg. The fuse on the main line from the battery only protects the circuit to and from the distribution panel .

Running lights, VHF, GPS, Bilge Pump (it should be wired separately to the battery), won't pull that many amps (20 or less). But if you wire to a 12V outlet, it could pull up to 15 amps depending upon what you plug in.

So again, for a little more money, I would go with #6 wire.

Tim & Dave Kinghorn

P.S. In our photos, you can see the electrical distribution box we use for two batteries with the Blue Sea circuit breakers.