How many cables fit on a busbar?

[Tellie]

With all due respect. This is where Sailors get their reputation for being cheap. A fire will put you in a life raft faster than a holing. It doesn't cost that much to do it right. Your boat costs a lot more than a few bucks. If I were to see this I would seriously worry about the rest of the electrical wiring on the boat. Seeing that I would drop my offer on a boat like this at least 15K.

[s/v Jedi]

Originally Posted by mvweebles

I stand corrected.
ABYC (E-11.16.4.1.11) does permit up to 4 conductors on a stud. That said, I doubt it was contemplated to have 4 heavy cables per stud with three similar companions in close proximity.

I would think a skilled electrician would be relieved you've decided to go with an 8 stud arrangement.

Good luck.

Peter

Well... I am a skilled electrician... and the only real reason not to do it is lack of expansion options.

In reality it gets crazier as some terminals will actually be terminal fuseholders but not on the busy negative busbar which is common for both 12V and 24V in our new setup.

Space is tight but we’ll make it pretty

[s/v Jedi]

Originally Posted by Tellie

With all due respect. This is where Sailors get their reputation for being cheap. A fire will put you in a life raft faster than a holing. It doesn't cost that much to do it right. Your boat costs a lot more than a few bucks. If I were to see this I would seriously worry about the rest of the electrical wiring on the boat. Seeing that I would drop my offer on a boat like this at least 15K.

This is done right and not only completely safe, it is within all codes and recommendations. A longer busbar with more studs does not reduce resistance. Stacking on a stud provides better contact between the stacked terminals than each on their own stud.

Also, there is nothing cheap on this install: it adds up to $18k

[mvweebles]

Originally Posted by s/v Jedi

Well... I am a skilled electrician... and the only real reason not to do it is lack of expansion options.

In reality it gets crazier as some terminals will actually be terminal fuseholders [emoji3] but not on the busy negative busbar which is common for both 12V and 24V in our new setup.

Space is tight but we’ll make it pretty

I have a similar situation with space and multi battery connections and feel your pain. I did not mean to deride your capabilities. I don't know you and assumed that since you asked the question, you wanted feedback. Just seemed like situation was ripe for trying to stuff 10 lbs of potatoes in a 5 lb sack.

[s/v Jedi]

Originally Posted by mvweebles

I have a similar situation with space and multi battery connections and feel your pain. I did not mean to deride your capabilities. I don't know you and assumed that since you asked the question, you wanted feedback. Just seemed like situation was ripe for trying to stuff 10 lbs of potatoes in a 5 lb sack.

Exactly, it feels like that for me too. It just shows that with engineering, feelings are not to be trusted. This is why we still have innovation: better options have often been overlooked because they don’t feel right until someone dives into it and works it out in detail, or does the experiments anyway. Look what Tesla and SpaceX are doing...

[Bycrick]

Stacking terminals isn’t a issue if they’re truly flat, good quality terminals. Otherwise, you might not get as good a connection across the various surfaces. Stacking four leaves the possibility of them moving back and forth, eventually loosening things. Maybe it’s necessary.

Using the 8-stud for the negative and the two others as 12 and 24 volt positives seems like a solution.

Since you mentioned power posts, the wire order on them isn’t the same as a bus bar. On the post, the high current connections go in the middle of the stack, with the lower current towards the top and bottom. Here, the problem is that if you have smaller wires/terminals at the top and bottom, it might be difficult to get enough even pressure on the big lugs in the middle.

[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

[chowdan]

Funny you asked this question! I was going through ABYC recommendations and also planned on doing this exact method. I'm fortunate enough to not worry about space and ended up getting an 8 stud bus bar(was going to stack 2 on 4 studs).

Out of curiosity, what sort of fusing are you going with? I'm thinking I'll likely mostly go with mbrf but not 100% sure.

[Dsanduril]

Even though this has been resolved, way back to the OP, the lock/split washers are still sitting on the desk and, except for stud #4, there are no threads left on the studs. Fully assembled with split washers or double nuts it seems the studs aren’t long enough to fit 4 terminals per stud and get the fasteners fitted.

[Factor]

Originally Posted by s/v Jedi

Well... I am a skilled electrician.:

Well then why did you bother asking?

[s/v Jedi]

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

In principal the same but for aviation it is stricter. The stud itself indeed is never relied on for conducting, it’s just for mechanical connection and clamping pressure

[s/v Jedi]

Originally Posted by Bycrick

Stacking terminals isn’t a issue if they’re truly flat, good quality terminals. Otherwise, you might not get as good a connection across the various surfaces. Stacking four leaves the possibility of them moving back and forth, eventually loosening things. Maybe it’s necessary.

Using the 8-stud for the negative and the two others as 12 and 24 volt positives seems like a solution.

Since you mentioned power posts, the wire order on them isn’t the same as a bus bar. On the post, the high current connections go in the middle of the stack, with the lower current towards the top and bottom. Here, the problem is that if you have smaller wires/terminals at the top and bottom, it might be difficult to get enough even pressure on the big lugs in the middle.

Indeed. Stacking order and strategic planning of electrical hi power connections is the norm. Hi current paths kept as short as possible, with as little contact surfaces as possible.

[s/v Jedi]

Originally Posted by chowdan

Funny you asked this question! I was going through ABYC recommendations and also planned on doing this exact method. I'm fortunate enough to not worry about space and ended up getting an 8 stud bus bar(was going to stack 2 on 4 studs).

Out of curiosity, what sort of fusing are you going with? I'm thinking I'll likely mostly go with mbrf but not 100% sure.

Yes, the mrbf fuses are great up to 300A. I am using ST blade for up to 30A, then the MRBF up to 300A and class-T up to 400.

[s/v Jedi]

Originally Posted by Dsanduril

Even though this has been resolved, way back to the OP, the lock/split washers are still sitting on the desk and, except for stud #4, there are no threads left on the studs. Fully assembled with split washers or double nuts it seems the studs aren’t long enough to fit 4 terminals per stud and get the fasteners fitted.

I tried all combinations: when all 4 terminals are 4/0 or 3/0 or a combination of the two, a lock washer can’t be used. 2x 4/0, 1x 3/0 and 1x 2/0 is the maximum size that the washer fits comfortably. In reality this is fine, but I used the big ones for the picture

[s/v Jedi]

Originally Posted by Factor

Well then why did you bother asking?

To discuss the subject. I am contributor on this forum... I do remember a couple instances where I asked for info but that is only 1 in every 1,000 posts or so