New Electrical System Questions

[ramblinrod]

Originally Posted by Frankly

Dan,

Good point you just don't have all the info. Output side Silicone Bronze bolt, G10, SB nut, SB flat washer, fuse blade, lug, flat washer, SB lock washer, SB nut. Don't know about getting a wrench to that bottom nut though.

The high amp fuse block is homemade but that is only because nobody had/ has chosen to produce such a beast. You could make it up from commercial components but not enough room in my case.

As to the feed for the BS fuse block, I admit to bending the rules a bit. I could have installed a say 50 amp fuse but what purpose would it serve. That fuse block is such an odd duck and I am using it in an odd fashion just didn't make sense. The total for those 6 ATO fuses is less than 40 amps and that assumes that all loads were at the fuse rating and on at the same time (none of which is true).

If some later nut comes along and loads it up with 30 amp fuses then let him swim home from the fire.

Yes, Sorry. I should have mentioned that in general, this is pretty good work (much better than what I usually see).

I was responding only to the specific query of another poster about fire risk, without being sensitive to the pride of the creator. It is abundantly clear that you have exceptional wiring skills.

The issue with the Blue Sea Fuse Block, is that if the positive side became short circuited to ground, the 8 AWG jumper could instantly light up. There should be protection against this possible occurrence.

To me, I'm not too concerned about the positive buss you created, but am about the risk of the insulation wearing through one of those wires at the bottom left corner should it contact the "Feed" stud or bar.

This is assuming that there is normally an insulating cover over the whole shebang, that is just temporarily removed to take the photo, else that is my biggest concern.

ramblinrod
About Sheen Marine

[Maine Sail]

Originally Posted by ramblinrod

The issue with the Blue Sea Fuse Block, is that if the positive side became short circuited to ground, the 8 AWG jumper could instantly light up. There should be protection against this possible occurrence.

In testing I have blown a 300A fuse with 15' of 8GA wire. The fuse blew in milliseconds and the wire never even had a chance to get warm to the touch.

In Frankly's case there is a 250A fuse ahead of the positive distribution fuse block, so in a dead short, even the 8GA wire is capable of taking out the 250A Class T. Ideal, no, but considerably safer than about 98% of the boats I set foot on...

[transmitterdan]

Originally Posted by Frankly

Dan,

Good point you just don't have all the info. Output side Silicone Bronze bolt, G10, SB nut, SB flat washer, fuse blade, lug, flat washer, SB lock washer, SB nut. Don't know about getting a wrench to that bottom nut though.

Thanks for posting the pic that shows the lower nut. That's very important as you obviously know. I'm sorry I didn't see that in the first pic. I see several times a year high current connections made where plastic is squeezed to get the pressure on the terminal and can't help pointing it out.

I agree with Mainesail, the really short jumper wires don't need another fuse. Those wires will blow a 300A fuse without melting.

[Nicholson58]

Originally Posted by transmitterdan

Frankly,

In the second photo where there are several fuses leading away from the main DC bus there appears to be a serious fire risk due to the design. Can you spot it?

I suspect the cover required by good sense & the usual surveyor is temporarily removed. Otherwise there is spark potential between the orphaned red on the right and the buss.

[Nicholson58]

Originally Posted by Frankly

Not sure I understand all the shunts. I decided to group all my battery negatives together and then use a single shunt feeding my link 10.

My charger tracks both battery banks simultaneously and can charge one, two or both and at different rates. Shunts are one per bank. Likewise, by Bogart battery monitors track power on each bank using the same two shunts.

There sure are a lot of ways to skin this cat.

I wonder if the OP ever got a satisfactory answer

[Frankly]

I will flip the black cable clamp around to put a little distance between the bus bar end and cable bundle. Distance is your friend where ground faults/ short circuits are concerned.

There is a lexan panel that swings down to cover the fuse area.

Blue Sea started in the right direction to help this problem with their Safety Hubs, but came a little light IMO. With the larger battery banks or Lithium whatevers (don't even want to think about the fault currents from 600AH worth of LION) somebody needs to give this a go (Blue Sea are you awake).

10 years messing with the Navy Seals helped shape my anvil mentality.

I think we solved all the worlds problems with this can of worms, but maybe a few good seed(s) got planted.

____________________

And when I fired off the Yanmar today "my Balmar was still putting out", so life is good.

Frank

[mitiempo]

Originally Posted by jongleur

I want to have
a house bank that is used for everything
including starting, and another battery used
exclusively if there is a problem with the house
bank. I went to Blue Seas's website and there
are two almost identical ACRs priced alike. I
have read their specs and neither one stands out.
Which one do I need, the SI or the Batterylink?

As jeepblue posted it makes no real difference. The price is similar. I think the SI will be stocked more commonly.

Make sure you run the alternator output as well as any other charge sources directly to the house bank, properly fused of course.

[jongleur]

Originally Posted by mitiempo

As jeepblue posted it makes no real difference. The price is similar. I think the SI will be stocked more commonly.

Make sure you run the alternator output as well as any other charge sources directly to the house bank, properly fused of course.

Will do.

[ramblinrod]

Originally Posted by transmitterdan

Thanks for posting the pic that shows the lower nut. That's very important as you obviously know. I'm sorry I didn't see that in the first pic. I see several times a year high current connections made where plastic is squeezed to get the pressure on the terminal and can't help pointing it out.

I agree with Mainesail, the really short jumper wires don't need another fuse. Those wires will blow a 300A fuse without melting.

Well, I'm gonna disagree. I should not have stated "instantly". But if those 8 gauge wires the max current they can, they will get hot. Maybe a dead short will trip a fuse, but higher impedance short will not, and they most definitely will light up.

Per ABYC every branch circuit off a main circuit having lighter gauge wires, requires independent current limiting, if the main circuit current limiting capability is too high for the branch circuit wiring. In this case, 250 A into 2 x 8 AWG ~ 3" wires, is too high. They will get hot and burn.

This most certainly is a potential electrical fire hazard. On the scale of likelihood, perhaps low, but that doesn't matter if the conditions exist to make it happen. There should be a fuse between.

Ramblin Rod

[ramblinrod]

Originally Posted by jongleur

I want to have
a house bank that is used for everything
including starting, and another battery used
exclusively if there is a problem with the house
bank. I went to Blue Seas's website and there
are two almost identical ACRs priced alike. I
have read their specs and neither one stands out.
Which one do I need, the SI or the Batterylink?

I would not recommend what you are planning.

If you wish to start the engine off the house bank (and have no dedicated, isolated start battery), that is a solution, running the risk of not being able to start the engine if the house bank is run down. (It never should be if the house bank is being monitored properly, but stuff happens.)

A better way is to have a dedicated start battery connected directly to the alternator, and the house bank combined via a diode isolator, 1/2/both switch, or ACR (in order of lowest to highest preference).

This way, the starting battery is dedicated to starting and used (successfully tested) every time the vessel is started. When (not if) the start battery fails, the house bank can be switched over to start the engine (assuming it is wired to do so).

It really doesn't make sense to have an isolated start battery, but to keep it as a back-up and use the house bank to start. (At least, I can't think of a valid, practical reason for doing so.)

I recommend connecting the alternator to the starting battery, and the house bank via an ACR. This way, the dedicated starting battery is tested every time you start the engine. When (not if) the starting battery fails, you can manually combine the house bank, to get you out of trouble.

The Blue Sea SI-ACR (start isolator) is the one I recommend to customers.

Ramblin Rod
About Sheen Marine

[jongleur]

Originally Posted by ramblinrod

I would not recommend what you are planning.

If you wish to start the engine off the house bank (and have no dedicated, isolated start battery), that is a solution, running the risk of not being able to start the engine if the house bank is run down. (It never should be if the house bank is being monitored properly, but stuff happens.)

A better way is to have a dedicated start battery connected directly to the alternator, and the house bank combined via a diode isolator, 1/2/both switch, or ACR (in order of lowest to highest preference).

This way, the starting battery is dedicated to starting and used (successfully tested) every time the vessel is started. When (not if) the start battery fails, the house bank can be switched over to start the engine (assuming it is wired to do so).

It really doesn't make sense to have an isolated start battery, but to keep it as a back-up and use the house bank to start. (At least, I can't think of a valid, practical reason for doing so.)

I recommend connecting the alternator to the starting battery, and the house bank via an ACR. This way, the dedicated starting battery is tested every time you start the engine. When (not if) the starting battery fails, you can manually combine the house bank, to get you out of trouble.

The Blue Sea SI-ACR (start isolator) is the one I recommend to customers.

Ramblin Rod
About Sheen Marine

Do you disagree with this:

1/BOTH/2/OFF Switches Thoughts & Musings | SailboatOwners.com Forums

[transmitterdan]

Originally Posted by ramblinrod

This most certainly is a potential electrical fire hazard. On the scale of likelihood, perhaps low, but that doesn't matter if the conditions exist to make it happen. There should be a fuse between.

Ramblin Rod

I am not an ABYC expert and don't want to pay to read the specifications. But most electrical codes make a distinction about short wires or bus bars from high current feeders to lower current branch circuit protection. Quite often the lower current protection device simply cannot handle the wire size otherwise required by the supply capacity. This example is like that. The runs are short and highly unlikely to ever have a "dead short" in the jumpers from the bus bar to the lower amperage fuses. Even batteries are allowed a short run of unfused wire according to the ABYC from what I have learned.

The bottom line is the solution is practical and not likely to ever be a problem. And there is no good way to make it better. So that's why I would leave well enough alone.

[darylat8750]

I'm not a professional but I think FRANKLY's solution is a beautiful thing. I certainly would not feel a need to change it. But for my education would making the connectors between the heavy bus and the Blue Sea out of fusable link make sense? Maybe make up a couple of extra to keep with the extra fuses?

[jeepbluetj]

Originally Posted by jongleur

Do you disagree with this:

1/BOTH/2/OFF Switches Thoughts & Musings | SailboatOwners.com Forums

I agree with that. Heck, that's how I wired my boat as I mentioned above. I sometimes have other folks using my boat and "Just leave it on 1 all the time" is far easier to communicate than the switching nonsense. And because my reserve battery is always charged, I can always start the engine in an emergency.

Some caveats: my aged Catalina 30 has an Atomic 4. Does not take a lot of power to start it. But as Maine Sail points out, neither does a small diesel.

And it's horses for courses. You're not jamming in 5 batteries in a Catalina 30. The reserve was hard enough to find a spot to put it in. Go to a 50 ft boat and a dedicated start, dedicated house, dedicated windlass setup starts to make far more sense.

On another point, I wouldn't loose a tiny bit of sleep over that feed to the blue sky box. Yea, it could be fused but the likelihood of a short that doesn't blow the battery fuse but does heat the wire for a long time is very very very small.

I'll admit that my boat has a much more dangerous situation - the first 6v isn't fused at all. My main battery fuse (ANL) is between the batteries, so it's a tiny bit safer than on the + output of the bank, but the +6v point could be described as dangerous. I'll bet dollars to doughnuts that everybody with 6v batteries has the same situation (unless you put a MRBF on the + terminal of every battery).

[exMaggieDrum]

I was an ABYC certified electrical tech for many years, blah blah blah, so I appreciate the safety of fusing every smaller cable that comes off a bus fed by a bigger cable. Certainly the bigger cable absolutely should be fused appropriately. And every cable, within practical reason, that is fed off the bus should be fused.

There is once case where that is not feasible or practical though. And that is when you are jumpering to another bus or terminal block in a very short space. In that case there may not be room for a fuse (the fuse block might be longer than the space available). If the jumper wire is the same size as the appropriate fused first bus feed cable, then no problem. You don't have to fuse every wire just because you have a bus or terminal in between, but the fuse has to be no larger than recommended for the total length of that size wire, i.e. before and after the intermediate bus/term.

There will be some times where you will only go off the feed bus with a short smaller feed wire to the next bus or term block. Then, the safest approach is to make the fuse on the big cable be the recommended smaller size for the smaller jumper. (Hope this makes sense.) But, so long as the other wires coming off the close bus or term block are smaller than the intermediate wire, and they are individually properly fused, then IMO it is OK to not have a fuse on the intermediate wire. But I'm talking small distance here.

Remember that in the recent past, ABYC did not recommend to fuse the large cables coming off the batteries much less in this situation. I don't have the current ABYC book so don't know the exact specs now, but so long as you properly secure the cables so that they cannot move nor vibrate loose off the bus then that can provide an appropriate level of safety, have good chafe protection (as needed), is the correct type of wire, blah blah blah. How long the unfused cable can be is critical as well.

So there will be times you just can't fuse every single wire in a circuit but you can and should mitigate that will other proper installation techniques.