How many cables fit on a busbar?

[Bycrick]

Storm along — Relax. It’s not that people are ignoring your advice. But your suggestion is ALWAYS the best answer. If I buy a four-stud busbar from PKYS, add $10 to ship to Miami. Another $10 shipping to Panama. Plus a cab ride out to pick it up. So, call it $100. 10 minutes to order it, an hour to pick it up.

The last time I built some, the 5/16”x1-14” real copper bus bar cost $100 for a 3” piece, bought locally because of time pressure. I built several and it was probably about equal cost to just shipping them in.

I can maybe buy it at the local chandlery for $125, plus cab fare. 10 minutes to buy it. Maybe $10 taxi if it’s a special trip.

With your approach, $12 for the metal, $10 shipping to Miami, $10 to Panama, 6 bolts/nuts/washers $6, find and cut mounting plastic/wood, drill the holes and assemble, two cab rides $20. So about $60 in parts, plus at least 4 hours time.

That is a low estimate all the way around. It values my time at maybe $10/hr. So, if the bar were open, I might well just figure it’s worth it to just buy the bus bar and spend my time drinking.

[Bycrick]

Above post, corrections. NOT ALWAYS and $100 for a 3 foot piece.

[chowdan]

When it comes time to sell or survey the boat, non-homemade bus bars won't be called out as well.

[stormalong]

Originally Posted by chowdan

When it comes time to sell or survey the boat, non-homemade bus bars won't be called out as well.

I doubt that a good surveyor would call out a properly made buss bar. The surveyor won't know if it was made by a marine electrician, boat yard, or the owner. What are the ABYC standards that would be violated?

[Fuss]

Double nuts on the studs. I don’t like it without double nuts on the studs.

[RaymondR]

Originally Posted by Singularity

FWIW...an aviation perspective.
FAA allows 4 lugs per stud, but:
-there needs to be a physical divider between studs
-some type of locking device required (lock washer/nut, not just Loctite)
-2-3 threads should show above nut after all torqued on (standard aviation practice)
-current should be carried by terminal bar (or sandwiched components, not relying on stud; maybe this is was addressed differently up-thread)

Not saying the above is required, and planes +/- have more vibration issues. Here's an FAA best practices document, terminal strips starting at page 101 (obviously references to aluminum and steel don't apply to boats):
https://www.faa.gov/training_testing..._printable.pdf

I found the aircraft recommended practices very interesting in that they address aluminium conductors.

A couple of years ago I expanded my solar farm and when it came to rewiring the new installation I became very dissatisfied with the amount of wiring and connections required. Consequently I decided to utilize aluminium bus bars. I was unable to find much information on the use of alloy in this application other than to find that it's use therein is becoming more common.

Being a suck it and see sort of bloke I decided to forge ahead and just see how it turned out. There is little risk in doing so as the solar farm is an all alloy construction.

I was concerned about potential dissimilar metal problems until I went to an electrical warehouse and found a paste used to prevent the problem with alloy bus bars.

I've not had any problems with the solar farm and am now considering rewiring the mess of cables in the battery box using aluminium bus bars. It is heartening to see that alloy is used in aircraft. I believe it has about 64% the conductivity of copper but is much more readily available and much lighter and less expensive.

[Manateeman]

Peaceful greetings to all. OK. The post on tin pox was great but now I’m more confused than ever. I’ve been told...don’t put any stuff between the lug and the bar. Then someone posted a list of anti corrosive pastes and what they are made of but I lost the thread. So I have new Blue Seas bars and two new BEP bars and some silicon bronze connector bars. So, put some Tef-Gel on the lugs to prevent tin pox? Nothing on the lugs, just spray anti corrosive after assembly?
I pulled apart some silicon bronze buss bars I made and used Ted-Gel on, and they looked like new. I used bronze bolts and heavy nuts and I’ve used 316 ss
bolts and nuts and t gel and I don’t see much of a difference.
Problem #2
My new main bank is 24 volts, four 6 volt Rolls FLA = 700 amp hours. Starting and nav stuff is a separate 12 volt system.
I like the way Vectron came off the bank with a big t class then on/off switch then buss bars to smaller fuses and loads. I’d like to place the on/off switch in the pilot house but that requires four feet of cable between the t fuse and the switch and more heavy cable to return to the buss bars. So...one one hand I gain a nice safe way to shut the main bank off...on the other hand, longer heavy cable and more connections. The USCG wants you to be able to shut the fuel off in a safe position but I’m not sure what they think is best for a battery disconnect access. Solenoid? Lot of juice under my pilot house floor. Opinions gentlemen?
Well, Happy trails to you.
Mark and the bemused and confused manatees

[GordMay]

"Tin Pest":
Below about 13.2 degrees C (±56F), tin can change to a brittle semiconductor, "grey tin" (or alpha tin), with a cubic (diamond) crystal structure.
“... Ordinarily, tin’s crystal lattice is tetragonal, with two square faces and four rectangular ones. Cooling the tin down reduces the amplitude of the atoms’ vibrations, and they can pack together into a more complex and space-efficient shape, shown below ...
This changes the way the electrons flow from atom to atom, rendering the tin useless as a conductor ...”
More ➥ Allotropy: Why Winter Spells Trouble for the Tin Man

[s/v Jedi]

Originally Posted by GordMay

"Tin Pest":
Below about 13.2 degrees C (±56F), tin can change to a brittle semiconductor, "grey tin" (or alpha tin), with a cubic (diamond) crystal structure.
“... Ordinarily, tin’s crystal lattice is tetragonal, with two square faces and four rectangular ones. Cooling the tin down reduces the amplitude of the atoms’ vibrations, and they can pack together into a more complex and space-efficient shape, shown below ...
This changes the way the electrons flow from atom to atom, rendering the tin useless as a conductor ...”
More ➥ Allotropy: Why Winter Spells Trouble for the Tin Man

When these black spots appeared, the busbars have never been under 20 degrees Celsius, let alone 13.2 degrees. So it may not be tin pest... they have been in a battery compartment where corrosive fumes from FLA batteries has been present. I used Trojan L16’s at the time. This also was a wet/humid space.

The new space will be dry and free from fumes as we don’t use FLA anymore.

When Scotchbrite the spots, the pest/corrosion/contamination or whatever it is goes all the way through the tin but the copper is unaffected. Liquid tin does not work on the spots while copper is tinned instantly. Logic dictates to remove the unknown spots and tin again.

Would Boeshield T9 be the best to spray the busbars and connections with after installation? Other options would be CRC corrosion block or even a conformal coating spray...

[s/v Jedi]

My first recommendation is an easy one: use a Blue Sea Systems 500A remote battery switch. It is a latching solenoid and gives you the option to switch from anywhere (even multiple locations) without even an inch extra cable.

I would not use TEF gel between lugs and busbar, nor any other compound. The tinned components are to be clamped tight, with the malleability of the tin creating a tight contact surface and the copper the conductivity. Best protection is probably the NO-OXID paste but I don’t want that on my busbars...

Originally Posted by Manateeman

Peaceful greetings to all. OK. The post on tin pox was great but now I’m more confused than ever. I’ve been told...don’t put any stuff between the lug and the bar. Then someone posted a list of anti corrosive pastes and what they are made of but I lost the thread. So I have new Blue Seas bars and two new BEP bars and some silicon bronze connector bars. So, put some Tef-Gel on the lugs to prevent tin pox? Nothing on the lugs, just spray anti corrosive after assembly?
I pulled apart some silicon bronze buss bars I made and used Ted-Gel on, and they looked like new. I used bronze bolts and heavy nuts and I’ve used 316 ss
bolts and nuts and t gel and I don’t see much of a difference.
Problem #2
My new main bank is 24 volts, four 6 volt Rolls FLA = 700 amp hours. Starting and nav stuff is a separate 12 volt system.
I like the way Vectron came off the bank with a big t class then on/off switch then buss bars to smaller fuses and loads. I’d like to place the on/off switch in the pilot house but that requires four feet of cable between the t fuse and the switch and more heavy cable to return to the buss bars. So...one one hand I gain a nice safe way to shut the main bank off...on the other hand, longer heavy cable and more connections. The USCG wants you to be able to shut the fuel off in a safe position but I’m not sure what they think is best for a battery disconnect access. Solenoid? Lot of juice under my pilot house floor. Opinions gentlemen?
Well, Happy trails to you.
Mark and the bemused and confused manatees

[s/v Jedi]

Originally Posted by RaymondR

I found the aircraft recommended practices very interesting in that they address aluminium conductors.

A couple of years ago I expanded my solar farm and when it came to rewiring the new installation I became very dissatisfied with the amount of wiring and connections required. Consequently I decided to utilize aluminium bus bars. I was unable to find much information on the use of alloy in this application other than to find that it's use therein is becoming more common.

Being a suck it and see sort of bloke I decided to forge ahead and just see how it turned out. There is little risk in doing so as the solar farm is an all alloy construction.

I was concerned about potential dissimilar metal problems until I went to an electrical warehouse and found a paste used to prevent the problem with alloy bus bars.

I've not had any problems with the solar farm and am now considering rewiring the mess of cables in the battery box using aluminium bus bars. It is heartening to see that alloy is used in aircraft. I believe it has about 64% the conductivity of copper but is much more readily available and much lighter and less expensive.

I am firmly against the use of aluminum for conductors in wiring as well as busbars. The only reason to use it is lack of budget for copper but plenty fires have started and people have died because of aluminum conductors.

[Bycrick]

Comments given without being able to cite sources.

The Blue Sea remote battery switches are great. And given 2/0 wire prices here, if I can eliminate 8’ of wire run, they’re the same or less cost. With shorter runs, they’re often just easier to install.

Aluminum conductors? I personally wouldn’t use it for wires on a boat. But for bus bars? They’ll be bigger, twice the cross sectional area, maybe corrode more if they get wet, but you don’t want them wet. If they’re big enough not to get hot, you shouldn’t have problems with thermal cycling.

I’m of the school that says that you clean the contact surface and lug, then assemble. If the lug is clamped tightly, there’s no space between the surfaces. The resistance of that connection ought to be about 1. -2/10,000 of an ohm or less. I can't see that anything between the surfaces is going to assist in reducing that number, and can potential increase it. After assembly, spray with something thin like T-9. If there happens to be a gap, it would wick in. Otherwise it just lays on the exposed surface and it’s cleaner and easier to remove than some other sprays. I’ve been known to put a little anti-seize on the SS stud to avoid galling with the SS nut. By comparison to the clamped surface, the washer, nut and stud carry almost no current, thus the grease there has little effect.

Just opinions.

[Frankly]

Originally Posted by Bycrick

I’ve been known to put a little anti-seize on the SS stud to avoid galling with the SS nut. By comparison to the clamped surface, the washer, nut and stud carry almost no current, thus the grease there has little effect.

Just opinions.

Use silicone bronze studs and avoid galling and dissimilar metals issues. Another advantage to the copper bar do it yourself version.


Frankly

[Bycrick]

If I were building them myself (see earlier post) and could find could find bronze bolts locally, I might. But Blue Sea and BEP use SS studs.

[Frankly]

They always have $$ as part of the equation, my thinking focused on quality (30 years with DOD will warp your perspective).

Bought my SB from Jamestown Distrubutors when all they sold was hardware.

Frankly