What about fuses with the switches at point of use?

[Chotu]

Originally Posted by Carlos M

You intend to tap several “much smaller wires for the LEDs” from the 4AWG protected upstream by a 50 A circuit breaker. Then you run those tap wires to the correspondent loads where you fuse and switch them. If I understood you correctly…

What will happen when one of these small tap wires chafes, get’s bitten by a rat, gets an anchor dropped on (whatever), leading to a defect of 48 A at the point of chafe?


There is a reason electrical distribution systems follow a radicular pattern.

Let me answer your question with a question.

Does your 200 amp battery cable fuse blow when you overload a 15amp breaker downstream of it?

Or does the smaller circuit protection device blow first?

[CaptTom]

I'm not sure I'm following all of this, but one fundamental misunderstanding a lot of people share is that the fuse or breaker is there to protect the equipment. It's not.

It's for the wires. The fuse or breaker must be sized to protect the wires from carrying more current than they are rated for. So it must be "upstream" of the wiring run.

In the example above, the 200A fuse is there to protect the battery cables. From there the next thing in line should be the 15A breaker protecting the wiring downstream of that. That wiring should be rated for 15A or better. On a boat you'll often find smaller loads (with correspondingly smaller wires) protected by an in-line fuse right where it connects to the terminals fed by the heavier (in this case, 15A-rated) wire. That protects the wiring from the terminal block to the device. The circuits inside the device itself are engineered to some fail-safe standard, like being enclosed in a metal box.

[Chotu]

Originally Posted by CaptTom

I'm not sure I'm following all of this, but one fundamental misunderstanding a lot of people share is that the fuse or breaker is there to protect the equipment. It's not.

It's for the wires. The fuse or breaker must be sized to protect the wires from carrying more current than they are rated for. So it must be "upstream" of the wiring run.

In the example above, the 200A fuse is there to protect the battery cables. From there the next thing in line should be the 15A breaker protecting the wiring downstream of that. That wiring should be rated for 15A or better. On a boat you'll often find smaller loads (with correspondingly smaller wires) protected by an in-line fuse right where it connects to the terminals fed by the heavier (in this case, 15A-rated) wire. That protects the wiring from the terminal block to the device. The circuits inside the device itself are engineered to some fail-safe standard, like being enclosed in a metal box.

Precisely. That’s the answer to my “answer in the form of a question” to Carlos.

If people are having a hard time understanding this new concept, and it’s not really that new, it’s called a distributed system, Picture it like this:

It’s like having a set of really long battery cables.

So each small new panel you hook up is connected directly to the battery cables.

That should help translate it into something everyone can picture on their own boat.

And they are smaller than regular battery cables because the loads are not even close. There is no inverter tied through these. There is no electric windlass. There is no high amperage battery charger or solar charge controller.

It’s just the regular DC loads of the boat that are low, but add up.

I am thankful that I was just forced to explain it, because I forgot one thing. I do have an electric winch going into this somewhere. I have to account for that. I had nearly forgotten.

[Carlos M]

Originally Posted by Chotu

Let me answer your question with a question.

Does your 200 amp battery cable fuse blow when you overload a 15amp breaker downstream of it?

Or does the smaller circuit protection device blow first?

No, it won’t. If all goes well it will respect the calculated selectivity and only the 15 A will open.

Again, I may have misunderstood you but you were considering the 15 A breaker at the end of the “small tap wire”. Leaving said wire unprotected. Or you would have to install the 15 A breaker at the tap point and have circuit breakers all over your boat, but I haven’t read you considering that.

[Carlos M]

Originally Posted by Chotu

Precisely. That’s the answer to my “answer in the form of a question” to Carlos.

If people are having a hard time understanding this new concept, and it’s not really that new, it’s called a distributed system, Picture it like this:

It’s like having a set of really long battery cables.

So each small new panel you hook up is connected directly to the battery cables.

If you understood and agree with what CaptTom so clearly explained above, you will have to install a circuit breaker at each tap point. To protect the smaller tap wire from the tap point to the load. Correct? Is that your intention?

[Chotu]

Originally Posted by Carlos M

If you understood and agree with what CaptTom so clearly explained above, you will have to install a circuit breaker at each tap point. To protect the smaller tap wire from the tap point to the load. Correct? Is that your intention?

I don’t like to parade it out there, but I was a physicist. I think I can handle a little tiny DC wiring project. Lol

of course I understood what Tom said and of course there will be some small breaker panels after the tap. That’s what it says in all of my posts above. It talks about a breaker panel at each tap into the main bus. Just like the title of the thread says. Having the switch is right at the point of use. Like at the helm for instance. At the watermaker and water pump area, stuff like that.

this is an infinitely better and more elegant way to do wiring than having a rats nest of tiny wires going from some central area.

Just because I ask a lot questions to fill in my gaps of knowledge in areas pertaining to Boat building (how I build my knowledgebase to include everything I can), doesn’t mean that I’m a complete idiot.

I was trusted enough to wire up things that are currently still in space and make the news sending back data sometimes, so I think I can do this.

I mean, I hate to sound like a pompous jerk, but you guys are treating me like I’m stupid. This isn’t a thread where I’m stupid.

Find me in the thread about how to do the running rigging on a performance catamaran or how to sail it by the numbers. Then you'll find a thread where I'm stupid. Lol

[Carlos M]

Originally Posted by Chotu

I don’t like to parade it out there, but I was a physicist. I think I can handle a little tiny DC wiring project. Lol

of course I understood what Tom said and of course there will be some small breaker panels after the tap. That’s what it says in all of my posts above. It talks about a breaker panel at each tap into the main bus. Just like the title of the thread says. Having the switch is right at the point of use. Like at the helm for instance. At the watermaker and water pump area, stuff like that.

this is an infinitely better way to do wiring then having a rats nest going from some central area.

Just because I ask a lot questions to fill in my gaps of knowledge in areas pertaining to Boat building, doesn’t mean that I’m a complete idiot.

I was trusted enough to wire up things that are currently still in space and make the news sending back data sometimes, so I think I can do this.

I mean, I hate to sound like a pompous jerk, but you guys are treating me like I’m stupid. This isn’t a thread where I’m stupid.

OK. Sorry if I offended you. I am not a native English speaker but reading back your whole thread I really thought you were proposing to do multiple taps on a main “bus” and run small wires from there to the load, fusing at the load’s end. It looks like I was misunderstanding you and just waisting my time. Good luck with the installation.

[s/v Jedi]

You don’t see that anymore because it has been obsoleted by CZone and compatible systems like offered by Yacht Devices. Here, the switch isn’t part of the circuit or it’s even been eliminated and replaced by an app on the plotter, tablet or smartphone.

My dimmer project has both: physical switches at point of use that are just microcontroller inputs, plus wifi access.

For my navlights, anchor light etc. I will use YD as well as physical switches on the main DC panel.

https://www.yachtd.com/products/circuit_control.html

[Chotu]

Originally Posted by Carlos M

OK. Sorry if I offended you. I am not a native English speaker but reading back your whole thread I really thought you were proposing to do multiple taps on a main “bus” and run small wires from there to the load, fusing at the load’s end. It looks like I was misunderstanding you and just waisting my time. Good luck with the installation.

sorry. I’m not offended. You are doing much better with English than I would with Portuguese. Ha ha.

it’s not even just you. There have been a lot of really annoying things on the forum lately. It’s probably time for me to go dark.

A lot of really annoying posts lately in my threads.

And I have about one week left to get everything done.

so the pressure is very intense. I worked on a joint project with ESA and NASA when I was a physicist. it was pretty cool. I got to stay in Germany for quite a while. And Switzerland. We worked in conjunction with the max planck institute over there.

so I respect the cultural and linguistic differences and I mean you no harm. Sorry if I got a little bit out of control there.

The pressure is really high right now. One week to do all of this. And I am facing many many tasks at once. And I’m trying to get through them as quickly as possible. I have been working 12 hour days seven days a week on the boat for at least the past three weeks to a month. I don’t even remember anymore.

And I’m a little stressed out because my helper is not around. He went away for Thanksgiving and has not come back. And there are things that I can’t complete without some help. He was supposed to be back yesterday. I’m hoping he’s back by Monday. I think he will be here, but it’s just an added stress. It’s holding me up on a lot of things I was trying to get done this weekend.

You see, I have to have the stern of the boat out of the water for a very small project that he has to do with epoxy. We have moved a lot of things to the bows in order to get the stern out of the water. I need to move those things in order to proceed on many projects. And I cannot proceed. He’s not here.

So it doubles and triples the stress when people on the forum make tasks more difficult to complete by trying to instill doubt, fear or to have me change course half way though a project.

There have been a lot of posts like that lately. And it’s been very very annoying.

So basically, I’m kind of losing my mind at this point. I’m trying to hang in there, but the stress levels are so high that I can hardly even describe it.

I certainly could have answered your posts with more tact and patience. That is my fault not your fault.

[Carlos M]

Originally Posted by Chotu

So basically, I’m kind of losing my mind at this point. I’m trying to hang in there, but the stress levels are so high that I can hardly even describe it.

I certainly could have answered your posts with more tact and patience. That is my fault not your fault.

No harm done. Just take it easy, one bit at a time. Good luck.

[rslifkin]

I'd skip the puncturing and just put a bus bar at each of the tap points (with appropriate crimped terminals on the big wire coming in and out of the bus). It'll be much easier to keep the wiring sealed that way. Plus, it makes it easy to change anything you need in the future.

[goboatingnow]

Originally Posted by rslifkin

I'd skip the puncturing and just put a bus bar at each of the tap points (with appropriate crimped terminals on the big wire coming in and out of the bus). It'll be much easier to keep the wiring sealed that way. Plus, it makes it easy to change anything you need in the future.

Agree leaving aside the rather bad idea of pulling expensive awkward to handle high power cable throughout the boat in the forlorn hope that some day it might be useful. I agree cutting it and using proper crimp terminals And local bus bars is best.

[s/v Jedi]

Originally Posted by rslifkin

I'd skip the puncturing and just put a bus bar at each of the tap points (with appropriate crimped terminals on the big wire coming in and out of the bus). It'll be much easier to keep the wiring sealed that way. Plus, it makes it easy to change anything you need in the future.

This is a perfect job for a powerpost, especially the Blue Sea Powerpost Plus which is like a mini busbar with small screws, plus unlimited current post for the trunk cables.

[goboatingnow]

[QUOTE=s/v Jedi;3711523]This is a perfect job for a powerpost, especially the Blue Sea Powerpost Plus which is like a mini busbar with small screws, plus unlimited current post for the trunk cables.

But the issue being discussed by the op is distributed switching not power distribution

[CaptTom]

Good discussion. I'd still vote for a central breaker / distribution panel, with home runs back to there from each load, for simplicity, reliability and safety. Of course there are other options, but there are reasons it's usually done this way.

This is different from the debate about where to put the switches. To me, the starting point for that discussion is to put aside the idea of switching devices from the breaker panel. That's not what the breaker panel is for. Put each switch where it makes sense.