Bus Bar question ???

[bluedolphin]

I'm not very good with marine electricals, so my question is - I want to add another bus bar because I have a few pos. and neg connections direct to the battery that I want to clean up. The bus bar I purchased said "100 amps", and it had 5 pairs of connectors. The sales person told me that the 1st connector on one side of the bar will be positive to the battery pos. On the other side will be the neg. connecor to the battery neg. If I have 4 or 5 different equipment to hook up to this bar, does the 100 amp mean I can not exceed that with the equipment I'm conencting to the bar? Thanks.

[RickK]

The rating is how much current the "bars" will handle.  I can't imagine that anything you connect to the bus bars - in total - will draw even a fraction of that rating.
Here is an example of non-power limited current - place your best pair of pliers across the buss bars so that it touches the + and - terminals and then the bars might melt (sorry about your pliers being welded to the terminals).  This is because there is nothing to limit the current except the pliers.  Again, as I said above, your equipment won't draw that much and if they start to, the fuse will blow before you toast the bars.

[bluedolphin]

Thanks, RickK. You mentioned a fuse - what amp fuse should I use? All the individual equipment have fuses. Do I need a fuse between the bar and the battery?

[RickK]

Nope.

[warthog5]

Yes you DO!

You need a fuse/CB [circuit breaker] CB is better that will handle ALL the current that all the load's combined will draw.

This CB will protect that wiring. That's what it's for.

This main feed wire should also have a ON/OFF switch in the circuit close to the battery.

[RickK]

You know, I stand corrected - I don't know what I was thinking - or wasn't.  I do think that you'll find more without inline fuses than ones with and certainly without the inline switch (mine included).

[bluedolphin]

Thanks, warthog5 and Rickk. So if the total amps of equipment on the busbar is, say 25 amps, should I have an inline fuse to the battery of 25 amps? You say CB, but I don't know how I could put a CB for just this application. If I was rewiring the whole boat, maybe.

[RickK]

This might help.  
http://www.powerstream.com/Wire_Size.htm
Depending on the size wire that is feeding the buss bar (and I don't know if there is a standard size or not), I would definitely fuse it smaller than the amp rating of the wire.  Example  according to that chart - 16ga can carry approx 22amps (and they say that this is conservative), so fuse it smaller than that - ie, 20 amp.
In the example of dropping the pliers across your buss bar that I posted earlier, the feed wire(s) would have smoked for sure, unless it was 0000 size  

[warthog5]

A lot of older boat's have a 10ga wire running forward to feed all the acc.

On a rewire I take that out and use 8ga. You have some different way's to do what I'm about to say here.

Just hook to the outfeed terminal of the battery switch with 8ga aprox 12in long or shorter. Then have a Blue Seas Bulkhead mount 30amp CB that, that cable hook's to. Come out of the CB and go forward to the POS buss bar.

The problem with that is it will be tied to the start battery. With electronic's connected to the POS buss bar and turned on, then you start the motor it will spike the electronics.

Not good for them and they will go thru a reboot.

This is where a house battery come's into play to stop that spiking problem.

See the post I did on installing a Blue Seas ACR.
http://www.classicaquasport.com/forum/v ... php?t=1583

This is a Blue Seas bulkhead mount CB.

[John Jones]

Good info Wart.

Not good for them and they will go thru a reboot.

Or like my father-in-law with an old GMC diesel with a generator, not alternator.  In a senior moment he turned all the electronics on before starting.  Smoked the radar, loran, and sounder in one shot.   :cry: