DC wiring for Inverter/Charger

[sailingharry]

So, I am in the midst of an LFP upgrade, so some wiring rework. I recently replaced my 1kW inverter/charger with a 3kW one, and knowing this was coming I didn't upgrade my wiring (I kept the old fuses, and just didn't use the extra capacity). Time to upgrade. And it looks like ABYC has changed in the 26 years since my boat was built.


I need to re-do two ground wires. One is the groundED conductor (the one that runs it), and it needs to be a 4/0 going eventually back to the battery. The other is the groundING conductor, and it is also a 4/0 (technically, it can be a 3/0 if you can find such a thing) and it also goes eventually back to the battery. ABYC says "engine ground or it's bus."


I don't like the way it's laid out right now. See attached pic. The ground wires go 2 feet to a terminal post (a big single-stud binding post). This post is under 1' from the negative shunt. The terminal post then sends a ground wire about 5' away to the ship's ground bus, a really hefty big bus in the engine room. It then goes 5' back to the shunt, and then to the battery. So, 8 terminal connections and about 14' feet of wire. UGH.


Putting aside ABYC for a moment, I'd love the negative wire to go either 3' to the shunt (I can put it on the shunt, and since it's far and away the biggest load on the boat, the fewer terminals and the shorter the wire, the better). Or, run it 2' to the terminal post, and then another 1' to the shunt. It drops from 8 terminals and 14' to 4 or 6 terminals and 3'.



So the groundING conductor, the case ground, is the issue. From a simple electrical view, a 1' conductor from the case to the spare negative terminal in the inverter would do it. But clearly, that's not really the ABYC intent. If I run the two ground conductors 2 feet to the terminal post, and then to the shunt, I'm not sure why that is safer/better than going to the terminal in the inverter. I could also run both to the shunt, but things start to get crowded (still legal, but crowded).


So, questions.
- What safety compromise is breached if I run the groundING conductor to the inverter terminal strip? I don't see it, but I do recognize that it seems like cheating.
- If I run both wires to the terminal stud, then to the shunt, then to the battery, is that legal? How is it different than treating the terminal block in the inverter as a terminal block?
- What is a "the engine or its bus?" It's not defined anywhere in E-11. I have a massive bus strip (2' long, with 9 cables over #2 and probably a dozen smaller), but if built from off-the-shelf components it would be multiple linked components, much like my shunt, bus bar, and terminal stud are all linked.

- I guess a fundamental question is, how far do the groundED conductor and groundING conductor have to stay discrete? It's impossible to stay separate all the way to the battery, because they have to stop before the shunt, regardless.

- And as an aside, 11.15.2.1.2 requires the groundING conductor to be green. I think (but it's not clear) that can be satisfied with green heat shrink on the ends -- but I've never seen green 4/0 cable!


This whole headache starts with the snarky "why can't I simply run it up to the inverter terminal strip" but when I say "duh, NO" I can't then figure out where I can go that is fundamentally different.

[sailingharry]

A bit of a follow up. ABYC A31 requires the battery cables to be supported within 6" of the device. At least on my Victron MultiPlus, the cables leave the box more than that distance from the mounting surface (and on mine, my cables go another direction. They even leave more than 6" from the side of the unit (at least, the side where my cables go). Meeting this 6" support rule bascialy requiries building a "support tower," a 7" high stack of wood right in front of the inverter box, to put a cable clamp on.


One solution would be to attach a block of wood the frame of the inverter, but that seems to present the same questions about the intent of A-31 that the ground wire presents -- does a support integrated into the inverter add value beyond what the inverter already provides?



What solutions have others come up with to meet this requirement? In a zero-base installation, you could mount the inverter with the output 4" from a bulkhead, and cable clamp the wires to the bulkhead.

[sailingharry]

I'm kind of surprised on one has struggled with how to comply with ABYC on these issues. Or even what ABYC is intending.

[newhaul]

Originally Posted by sailingharry

I'm kind of surprised on one has struggled with how to comply with ABYC on these issues. Or even what ABYC is intending.

On small things most just give the ABYC a coursery read and follow close just not letter of the recommendation. Now on the big things we'll they did the reserch so why not follow recommendations.

Read the section of lifepo4. It's even more confusing than the ISO section of European regulations concerning lifepo4.
Easy to follow just not easy to read .

[sailingharry]

So, NewHaul, where did you run the grounding wire (not the negative power wire, the 4/0 safety wire that carries zero current)? I can't even begin to figure out the intend of ABYC.


While I really can't get on board with the importance of this wire, they give several paragraphs to it and require it to be massive (same size as the power wire, although they allow one size under). So where do they want it to go? They use a term ("the engine or its bus") without defining it anywhere. I'm leaning heavily toward making it 16" long and going from the case to the spare lug on the negative input to the inverter -- I can't make a case for how this is different than anything else. But it feels terribly "wrong."




And how do you support your power wires within 6" of the unit, when they are 6" in the air (at least on a MultiPlus).


In this case, it's the reverse of your "easy to follow, just not easy to read." I'd say it's "easy to read, just not easy to follow."


I've just today come across an interesting similar problem with extremely poor definitions in the standards. The wire from the battery to the fuse cannot be over 7" long -- super easy to read. Except. My 4/0 lugs are almost 3" long each. Two lugs are close to 6" in lug. If the 7" standard is "tip to tip" you can have under 2" of cable between the lugs! That's not a cable, that's a bus bar! Sure you can sheath it (and I'm going to have to, because the cable part alone will be 9" for my installation), but I honestly don't know what ABYC means with the standard.


I'm intrigued by your comment that ABYC E-13 is even more confusing than the ISO standard. Have you read the ISO standard? It's not free, and unlike ABYC there doesn't seem to be an easy way to get them for free. Since I'm active on the ABYC committee revising E-13 (and hope to be a voting member early next year), and I'd love to see (or understand) the differences. My concerns about E-13 have little to do with readability or implementation, but mostly about the mixing of LFP and other chemistries in one standard. I do know that the ISO standard (ISO/TS 23625:2021)
has the same issue with combining chemistries -- it is titled "Small craft — Lithium-ion batteries."

[donradcliffe]

I agree that AYC has come off the tracks with resect to both fusing and grounding. It is like the NEC; we can't afford this level of belt and suspenders safety.

[newhaul]

Originally Posted by sailingharry

So, NewHaul, where did you run the grounding wire (not the negative power wire, the 4/0 safety wire that carries zero current)? I can't even begin to figure out the intend of ABYC.


While I really can't get on board with the importance of this wire, they give several paragraphs to it and require it to be massive (same size as the power wire, although they allow one size under). So where do they want it to go? They use a term ("the engine or its bus") without defining it anywhere. I'm leaning heavily toward making it 16" long and going from the case to the spare lug on the negative input to the inverter -- I can't make a case for how this is different than anything else. But it feels terribly "wrong."




And how do you support your power wires within 6" of the unit, when they are 6" in the air (at least on a MultiPlus).


In this case, it's the reverse of your "easy to follow, just not easy to read." I'd say it's "easy to read, just not easy to follow."


I've just today come across an interesting similar problem with extremely poor definitions in the standards. The wire from the battery to the fuse cannot be over 7" long -- super easy to read. Except. My 4/0 lugs are almost 3" long each. Two lugs are close to 6" in lug. If the 7" standard is "tip to tip" you can have under 2" of cable between the lugs! That's not a cable, that's a bus bar! Sure you can sheath it (and I'm going to have to, because the cable part alone will be 9" for my installation), but I honestly don't know what ABYC means with the standard.


I'm intrigued by your comment that ABYC E-13 is even more confusing than the ISO standard. Have you read the ISO standard? It's not free, and unlike ABYC there doesn't seem to be an easy way to get them for free. Since I'm active on the ABYC committee revising E-13 (and hope to be a voting member early next year), and I'd love to see (or understand) the differences. My concerns about E-13 have little to do with readability or implementation, but mostly about the mixing of LFP and other chemistries in one standard. I do know that the ISO standard (ISO/TS 23625:2021)
has the same issue with combining chemistries -- it is titled "Small craft — Lithium-ion batteries."

First my comment saying not easy to read part is all the extra words that describe everything . They are not concise and to the point . Makes it confusing just like your example. The wire to fuse length imo it should state specificly like thus . The wire shall be no more than 7 inches between lugs inclusive. Which in your case the wire would be a total of 13 inches tip to tip.

Now the grounding safety wire ? On what? I have not read the ABYC recommendations in well over 2 years.

The iso was posted in one of the threads I'm a contributor to from 3 or 4 years ago I forget the specifics. ( to concerned with wife's health and cancer treatment. She's all good now just getting back to normal health)
As to supporting the wires within 6 inches of the unit I use the trace 2512 inverter charger whose power connections are 4 inches off the deck I have the unit mounted on so wires come from unit downtown the deck and are secured there with screw lug zip ties.
What is stopping you from doing similar on your multiplus?
The unit is mounted somewhere so connections are no more than 2 or 3 inches from the bulkhead you are mounted on.

If you have any other specific questions I can ask my youngest to get me a copy of the ABYC recommendations that he has to follow as a lead installer/ engineer for delta marine here in Seattle.

[sailingharry]

Originally Posted by newhaul

First my comment saying not easy to read part is all the extra words that describe everything . They are not concise and to the point . Makes it confusing just like your example. The wire to fuse length imo it should state specificly like thus . The wire shall be no more than 7 inches between lugs inclusive. Which in your case the wire would be a total of 13 inches tip to tip.

The exact words are "Ungrounded conductors shall be provided with overcurrent protection device within a distance of seven inches of the point at which the conductor is connected to the source of power measured along the conductor." I read that as centerline of hole to centerline of hole. They could (should!) have added words as you've suggested. The issue is that the words are TOO simple, not that they are too verbose! In practice, it is essentially impossible to comply -- unless you then follow Exception 2. "if the conductor is connected directly to the battery terminal and is contained throughout its entire distance in a sheath... not to exceed 72 in." This is easy -- buy some of that split loom material and sheath it. But the 7" rule is just a few inches too short for "reasonable."

Originally Posted by newhaul

Now the grounding safety wire ? On what? I have not read the ABYC recommendations in well over 2 years.

The case of any inverter (unless it is a plastic case) must be grounded with a safety wire to "the engine or its bus." This wire must be no smaller than one size smaller than the power wire (in my case, with a 3kW inverter, it needs to be a 3/0). The question is, where does that wire need to go? In my case, my wiring is laid out similar to the attached diagram (better than my last one!). The black wire is the current ground wire. The new ground wire is the yellow one. The best (but perhaps tongue in cheek) safety wire is the green one. The issue is, What is the "engine or its bus?" If I can't use the green wire as shown, where SHOULD it go? I really don't know. The attached drawing has possible choices labeled A through E -- what is the difference between them, if any, and what does ABYC want me to do? I'd prefer A as the cheapest and easiest, but only if it also is a compliant and safe way.

Originally Posted by newhaul

As to supporting the wires within 6 inches of the unit I use the trace 2512 inverter charger whose power connections are 4 inches off the deck I have the unit mounted on so wires come from unit downtown the deck and are secured there with screw lug zip ties.
What is stopping you from doing similar on your multiplus?
The unit is mounted somewhere so connections are no more than 2 or 3 inches from the bulkhead you are mounted on.

The MultiPlus is not quite so convenient. Here is a picture of the unit (found on the web). The battery cables come out of that slot at the upper right, and that slot is 6" above the floor (so the floor isn't the answer. In my installation, I have a shelf even with that outlet to the left which my wires run on, but again that's more than 6" away. Which is why I'm thinking a couple of 2x6 screwed together to make a 4x6 (actual 3x5.5), and mount it on edge in front of the inverter. UGLY! Or, screw a 2x3 to the unit crosswise just below the outlet, slightly cleaner but not sure it meets the intent. Even your 4" above the deck takes some tight bends to keep below 6".

[newhaul]

Originally Posted by sailingharry

The exact words are "Ungrounded conductors shall be provided with overcurrent protection device within a distance of seven inches of the point at which the conductor is connected to the source of power measured along the conductor." I read that as centerline of hole to centerline of hole. They could (should!) have added words as you've suggested. The issue is that the words are TOO simple, not that they are too verbose! In practice, it is essentially impossible to comply -- unless you then follow Exception 2. "if the conductor is connected directly to the battery terminal and is contained throughout its entire distance in a sheath... not to exceed 72 in." This is easy -- buy some of that split loom material and sheath it. But the 7" rule is just a few inches too short for "reasonable."




The case of any inverter (unless it is a plastic case) must be grounded with a safety wire to "the engine or its bus." This wire must be no smaller than one size smaller than the power wire (in my case, with a 3kW inverter, it needs to be a 3/0). The question is, where does that wire need to go? In my case, my wiring is laid out similar to the attached diagram (better than my last one!). The black wire is the current ground wire. The new ground wire is the yellow one. The best (but perhaps tongue in cheek) safety wire is the green one. The issue is, What is the "engine or its bus?" If I can't use the green wire as shown, where SHOULD it go? I really don't know. The attached drawing has possible choices labeled A through E -- what is the difference between them, if any, and what does ABYC want me to do? I'd prefer A as the cheapest and easiest, but only if it also is a compliant and safe way.







The MultiPlus is not quite so convenient. Here is a picture of the unit (found on the web). The battery cables come out of that slot at the upper right, and that slot is 6" above the floor (so the floor isn't the answer. In my installation, I have a shelf even with that outlet to the left which my wires run on, but again that's more than 6" away. Which is why I'm thinking a couple of 2x6 screwed together to make a 4x6 (actual 3x5.5), and mount it on edge in front of the inverter. UGLY! Or, screw a 2x3 to the unit crosswise just below the outlet, slightly cleaner but not sure it meets the intent. Even your 4" above the deck takes some tight bends to keep below 6".

Ok the first one says " overcurrent protection device within a distance of seven inches of the point at which the conductor is connected to the source of power measured along the conductor."
Which to me means exactly what it says within 7 inches of the source . No mention of the distance to the load .


Second the inverter.
Mine is case grounded to the ships grounding buss. Which includes a grounding strap from the engine as well .

Cables on inverter mine are vertical stids out the back of the case so leads are pointed straight down I have them restrained on the mounting shelf at the back base of my inverter.
I oriented the leads straight down and not sideways.

This is a screen grab of one at the chandler near me .

[sailingharry]

Originally Posted by newhaul

Ok the first one says " overcurrent protection device within a distance of seven inches of the point at which the conductor is connected to the source of power measured along the conductor."
Which to me means exactly what it says within 7 inches of the source . No mention of the distance to the load.

Yes, I am talking about that first short wire, between the battery and the Class-T. ABYC aside, it's going to be short (24" would be way too long). But how is it measured. And this isn't "just semantics." A surveyor who has this as his "hot button item" could look at a 9" wire and write it up as an "underwriting issue" and then it is no longer a question of "is it really OK" and becomes a "must be fixed to keep insurance" issue."

Originally Posted by newhaul

Mine is case grounded to the ships grounding buss. Which includes a grounding strap from the engine as well.

Going, as you did, to the ship's grounding bus, is a logical interpretation. In my case, that's a 7' long run, followed by another 4' to the battery. That first run, a 4/0 7' long, is $70 in cable! It also results in a total run to the battery of 11', with 8 terminations. Or, I can run it 16" up to the negative terminal on the inverter, for $15 in cable, with a total of about 6' of run to the battery and 6 terminations. Or even better, to the shunt, with a cable of 3' ($30) and a total run of 4' with 4 terminations. The bus bar "seems" by far the worst option, but "seems" to be what ABYC requires. The bus bar run is almost 3 times as long, with twice as many terminations. But is this what ABYC actually requires, and why?


I know we have ABYC certified electricians on this site. I know we have skilled surveyors who inspect for this stuff on this site. I know we have folks who are active in ABYC committees on this site. These questions should be seen/implemented on a regular basis, and aren't exactly oddities. Every single MutliPlus installation has the issue with support. Every single inverter deals with where to run the grounding wire. Every single large battery cable (4/0) has to consider the 7" rule. I'm surprised the "accepted answer" hasn't been given.

[newhaul]

Originally Posted by sailingharry

Yes, I am talking about that first short wire, between the battery and the Class-T. ABYC aside, it's going to be short (24" would be way too long). But how is it measured. And this isn't "just semantics." A surveyor who has this as his "hot button item" could look at a 9" wire and write it up as an "underwriting issue" and then it is no longer a question of "is it really OK" and becomes a "must be fixed to keep insurance" issue."




Going, as you did, to the ship's grounding bus, is a logical interpretation. In my case, that's a 7' long run, followed by another 4' to the battery. That first run, a 4/0 7' long, is $70 in cable! It also results in a total run to the battery of 11', with 8 terminations. Or, I can run it 16" up to the negative terminal on the inverter, for $15 in cable, with a total of about 6' of run to the battery and 6 terminations. Or even better, to the shunt, with a cable of 3' ($30) and a total run of 4' with 4 terminations. The bus bar "seems" by far the worst option, but "seems" to be what ABYC requires. The bus bar run is almost 3 times as long, with twice as many terminations. But is this what ABYC actually requires, and why?


I know we have ABYC certified electricians on this site. I know we have skilled surveyors who inspect for this stuff on this site. I know we have folks who are active in ABYC committees on this site. These questions should be seen/implemented on a regular basis, and aren't exactly oddities. Every single MutliPlus installation has the issue with support. Every single inverter deals with where to run the grounding wire. Every single large battery cable (4/0) has to consider the 7" rule. I'm surprised the "accepted answer" hasn't been given.

My grounding buss bar is less than 12 inches from my inverter.

The main reason is that the ABYC is not a governing body so it's all up to interpretation and most owners really don't give a s. T about it .
I have never had a surveyor really get that deep into the vessel .

Myself I really don't dig that deep into the specifics of the boats I'm surveying.
If the installation looks good and neat then I'm usually satisfied. ( unless they are way out of spec. ) in other words I'm not breaking out a tape measure)

[smac999]

Battery - shunt - main neg bus bar. Neg and chassis wires to bus bar.

Not that hard.

[newhaul]

Originally Posted by smac999

Battery - shunt - main neg bus bar. Neg and chassis wires to bus bar.

Not that hard.

Exactly and that is best practice
However

That is not what the ABYC has written.
and that is the problem we are discussing . How the ABYC committee has written their recommendations.

[sailingharry]

Originally Posted by smac999

Battery - shunt - main neg bus bar. Neg and chassis wires to bus bar.

Not that hard.

So, as I've said, that results in a 12' run for something that can be done in 4'. And in the case of the grounding wire, something that can be done in 16 inches.


Remember, the entire power system is basically designed for the inverter. Nothing else on the boat even comes close to that power draw. So, the bus bar is neatly mounted on the side of the quarter berth structure, in a place that is easy to run wires to -- but results in an incredibly long run for the inverter, wisely mounted inches from the battery.



The negative wire (the black wire, properly called the grounded wire) can go pretty much any way I want it to. I'll run it to the shut, cutting the cable run by 66% -- a notable goal in 300A cable runs!



The grounding wire (the green one), is specified to go to the engine or its bus. That's the one that makes no sense. How is a 7' wire (to the bus) followed by a another 5' to the battery, better or safer than going to the spare terminal on the inverter? And what exactly IS the "engine or its bus?"


That last bit is the crux of the matter. ABYC wants it to go to the "engine or its bus." I have 6 places I can send that wire, all electrically connected (and electrically connected to the engine too!) -- are they all "the engine or its bus"


Since there is no fundamental difference between any of those 6 points (and since I can't even see a real purpose for that wire anyway), I'm leaning really strongly on the cheap/easy/clean solution, of a 16" wire from the case to the negative terminal.

[newhaul]

Originally Posted by sailingharry

So, as I've said, that results in a 12' run for something that can be done in 4'. And in the case of the grounding wire, something that can be done in 16 inches.


Remember, the entire power system is basically designed for the inverter. Nothing else on the boat even comes close to that power draw. So, the bus bar is neatly mounted on the side of the quarter berth structure, in a place that is easy to run wires to -- but results in an incredibly long run for the inverter, wisely mounted inches from the battery.



The negative wire (the black wire, properly called the grounded wire) can go pretty much any way I want it to. I'll run it to the shut, cutting the cable run by 66% -- a notable goal in 300A cable runs!



The grounding wire (the green one), is specified to go to the engine or its bus. That's the one that makes no sense. How is a 7' wire (to the bus) followed by a another 5' to the battery, better or safer than going to the spare terminal on the inverter? And what exactly IS the "engine or its bus?"


That last bit is the crux of the matter. ABYC wants it to go to the "engine or its bus." I have 6 places I can send that wire, all electrically connected (and electrically connected to the engine too!) -- are they all "the engine or its bus"


Since there is no fundamental difference between any of those 6 points (and since I can't even see a real purpose for that wire anyway), I'm leaning really strongly on the cheap/easy/clean solution, of a 16" wire from the case to the negative terminal.

Potential short in the ac side grounding the cabinet. Is the reason but that side also has the white and green wire d es to the ac grounding system . So imo should not even involve the dc side . Take it to the ships bonding ground . And doesn't need to be a large wire either.