Bus Bar size

[RVG8tor]

I have looked in several places including the bible AC43 and can't find out how to size the buss bar. One of the books from Tony Bengalis shows some diagrams with copper bar .032 x 3/8". Is there some formula or way to determine the size, is copper and brass the same? B&C sells .025 x 1/2" brass but 1/2" seems a little big for the application. Maybe some of you professional panel builder can tell me what you use.

[guccidude1]

The professional builder, avionics tech with a CNS router, connected my circuit breakers with the pre-punched 1/4" bar. I don't know what the material is but it is very thin and can be purchased at electronic stores very reasonably. It spaces the breakers at the correct spacing. Dan

[mburch]

You could figure out what the equivalent wire size would be based on the current requirements, then find a piece of bus bar stock with a cross-sectional area equal to or greater than that of the wire. If I am doing the math correctly, a 0.5" wide piece of 0.062" copper bus bar stock has a bit more copper in it than a piece of #6 copper wire.

mcb

[az_gila]

Originally Posted by mburch

You could figure out what the equivalent wire size would be based on the current requirements, then find a piece of bus bar stock with a cross-sectional area equal to or greater than that of the wire. If I am doing the math correctly, a 0.5" wide piece of 0.062" copper bus bar stock has a bit more copper in it than a piece of #6 copper wire.

mcb

...and you use the Vans copper strip as mentioned above --

Part Number = ES BUSS BAR-063X.5X12

-- it is 1/16 inch thick and is just less than a #4 wire.

The better practice is to use two of these strips in parallel if the starter current is running through them, and then you are equivalent to a bit better than a #2 wire.

[Canadian_JOY]

Not having a handy supply of buss bar material I decided to improvise and used (I shudder to admit it... LoL) 3/4" copper water pipe, sawed down to an appropriate width to fit the breaker attachments - each buss bar is likely 3/4" wide, and since it hasn't been hammered flat or otherwise bent it remains in its original ductile state. Areas not in contact with the breaker tabs are insulated with heat shrink tubing.

The array of breakers is set up to provide 4 rows of breakers. The main battery connection is virtually in the center of this array. Each row of breakers is tied together with its own copper buss bar and that buss bar is fed from the central feed point with a large-gauge wire (I have less alternator output than most RV's so my feed wires are 10AWG).

I wondered how well this setup would work so I tested it using battery power as my source of energy and then applying a large resistive load to the circuit supplied by the breaker the located furthest from the central feed point. That particular breaker is a 5 amp breaker and at full rated load and a battery voltage of about 12.2VDC I had difficulty measuring any voltage drop between feed point and the breaker. This made me feel my solution was workable.

Never too content with going on trust, I've been re-torquing the circuit breaker screws at each annual inspection, and at the same time looking for any signs of heat distortion, arcing, etc. So far, 2.5 years after initial installation, all is well. None of the CB screws have experienced a drift in screw torque and other than some slight discolouration where my fingers touched the bare copper, the buss bars look the same as the day they were installed.

Net cost for these home-brew buss bars was about two bucks...

[Mike S]

I did almost the same thing, used 1" copper pipe coupling.

I would band saw off a ring 3/8" wide, cut it open, and straighten it out flat.

Instant buss bar, 3" long.

In the ten, no buss bars in the starter circuit.

[RVG8tor]

What does this mean? Isn't that the way it is set up in all of the Z diagrams, no bus bar in the starter?

Signed confused!