electrical panel question

[azazzera]

I have just installed a blue sea dc only panel. Im studying the installation instructions and have a question on running the negative wires. There is a negative bus on the panel but I don't see the need to run the wire from each load directly back to the panel bus. my plan was to run them to a location close to the panel on a separate wire block then have that block connected back to the battery with a wire that can handle the current of all the wires. I think it will be cleaner and less congested on the panel doing it this way. Is there a problem with doing it this way.

[ndutton]

There's no electrical reason not to do it as you described BUT you may still want to run each circuit negative as far as possible along with the positive, even twist them together, all the way to the distribution panel. The reason is so the current flowing in the conductor pair (equal but opposite) cancels out the Gauss field surrounding the single conductors. Your compass will be happier.

[hanleyclifford]

I have just installed a blue sea dc only panel. Im studying the installation instructions and have a question on running the negative wires. There is a negative bus on the panel but I don't see the need to run the wire from each load directly back to the panel bus. my plan was to run them to a location close to the panel on a separate wire block then have that block connected back to the battery with a wire that can handle the current of all the wires. I think it will be cleaner and less congested on the panel doing it this way. Is there a problem with doing it this way.

No problem; just make sure the negative runs are sized the same as the positive. I use a similar panel and a #6 works well for the negative home run.

[joe_db]

You can use a ground bus elsewhere, but you still need to run a ground wire to the panel, if for no other reason then making the backlights and indicator lights work

[BunnyPlanet169]

I did something similar, although I used breakers, not a pre-made panel.

Here's the negative side: http://www.moyermarine.com/forums/al...pictureid=1561

Because all my house loads are on this terminal block, the feed and return are sized at full design current, with a healthy margin.

Remember that the size of the conductors have to account for the full length of the circuit, both positive and negative. And while the cable is expensive, you may add loads in the future and you only want to do the feed and return once. Be conservative in your calculations, and then go bigger.

[Al Schober]

Remote ground bus is no problem. Don't forget that the positive lead from the battery to the panel needs circuit protection - the fuse has to be close to the battery (not sure of the max distance).

[azazzera]

One more question. At least for now

Thank you for the responses so far. This panel has a shunt for an ammeter. My thought was to as per the blue sea app use a #4 wire to the shunt then a 4 from the other side to the first bus bar of the panel. The panel is a 100 amp. Then use jumpers in a series to the secound buss bar and then another to the third and final positive bar. My question is, is this electrically kosher, and if it is can I reduce the size of the wire with each subsequent jump. I would assume that the second jumper would need to be sized for any current down stream of it. And so on. I would make sure that the bus bar screws were long enough to capture two ring terminals. There are also positive and negative wires for a led back lights. Could I simply conect the positive wire back onto the positive bus bar. Trying to make all wire runs as short as possible.

Thanks again for all your advice.

[BunnyPlanet169]

I'm surprised Blue Sea doesn't provide a factory buss bar option to tie the positives together. They do for ganging their switches.

Where's the fuse that protects the #4 positive wire? Should be very close to the battery (nominally <= 7").

That fuse protects everything after, so no, the jumpers should all be #4. You're correct in knowing the nominal loads probably decrease with each subsequent buss bar, but the circuit protection is for full load (E.G. Imagine a dead short from the last bar), and each jumper is only protected if it can also support the full load.

[hanleyclifford]

Please post the item number of that Blue Seas panel. If we study it for a bit I think we can give more useful answers to your questions.

[ndutton]

Jeff is on it. The fuse protects the downstream wiring, all of it up to the point of the next overcurrent protection so to be Kosher, all wiring protected by your 100 amp fuse should be 100 amp rated.

[azazzera]

Didn't think about a dead short. That's why I its so good to ask questions. So if my knowledge is sufficient a dead short on tha last bar in the series will get full amp of whatever battery it's connected to. Hence the fuse <=7 inches away. And the fuse size should be larg enough to handle full load from the panel. I think I can go 150% of the load on the fuse. Not sure about that one. The wire of course needs to be large enough to handle the current I plan to pass through it. Must always remember that's what I'm trying to protect not the load or device. As far as led back light wires the simply emerg from under a circuit board. The tag on the wires state to hook positive to positive and negative to negative. I may decide to hook them up to a switch so the lights are not always on but I'm still thinking about that one. The closest positive source is the positive bus bar to the beakers. So I guess that they don't pre wire them because they may want to be switched. My plan was to go from battery to battery switch then from common from switch to panel and to starter stud. Two wires off of the common stud of battery switch. How am I doing so far. My one concern is where to place the fuse for panel. Only place is after common stud feed wire but may violate 7 once rule based on place of my battery's. Plan on using #2 wire from battery's to battery switch. And from common to starter. Understand it my be excessive.

[hanleyclifford]

Didn't think about a dead short. That's why I its so good to ask questions. So if my knowledge is sufficient a dead short on tha last bar in the series will get full amp of whatever battery it's connected to. Hence the fuse <=7 inches away. And the fuse size should be larg enough to handle full load from the panel. I think I can go 150% of the load on the fuse. Not sure about that one. The wire of course needs to be large enough to handle the current I plan to pass through it. Must always remember that's what I'm trying to protect not the load or device. As far as led back light wires the simply emerg from under a circuit board. The tag on the wires state to hook positive to positive and negative to negative. I may decide to hook them up to a switch so the lights are not always on but I'm still thinking about that one. The closest positive source is the positive bus bar to the beakers. So I guess that they don't pre wire them because they may want to be switched. My plan was to go from battery to battery switch then from common from switch to panel and to starter stud. Two wires off of the common stud of battery switch. How am I doing so far. My one concern is where to place the fuse for panel. Only place is after common stud feed wire but may violate 7 once rule based on place of my battery's. Plan on using #2 wire from battery's to battery switch. And from common to starter. Understand it my be excessive.

Use of #2 as you describe is not excessive. Since the panel uses a shunt type ammeter, which will be in the negative loop if it is like other Blue Sea meters, why not put your protection (150 amp breaker) right next to it?

[azazzera]

Just to be clear the #2 will be from battery to battery switch. Thinking about a post style fuse for those main branch #2s. I would be pleased to put the panel fuse next to the shunt but that would be about 2-3 feet away from battery. In violation of that 7 inch thing. And the instructions I have on this panel instructs to place the shunt on positive side. What's the difference.

[hanleyclifford]

Just to be clear the #2 will be from battery to battery switch. Thinking about a post style fuse for those main branch #2s. I would be pleased to put the panel fuse next to the shunt but that would be about 2-3 feet away from battery. In violation of that 7 inch thing. And the instructions I have on this panel instructs to place the shunt on positive side. What's the difference.

Shunt on the positive side would be new to me, but I do welcome the change if Blue Seas has made it. I would like to study the details on your panel since it seems my knowledge is out of date. Could you say the model number? I will get the instructions on line and refrain from any more statements until I get up to speed.

[azazzera]

https://www.bluesea.com/products/8378/DC_18_Position

That sould get you to the panel with a link to the instructions. If the link is bad the panel # is 8378. What is the difference between positive and neg loop placement. To my thinking the shunt on positive whould "see" everything after it and after would see before it. I would think intuitively it would be better on positive feed. You would see complete current draw of each load in use.

Now for the caveat. I'm pretty sure I read the schematic correctly.