Examples where excess cables are zip tied in a loop on my boat are Airmar transducer cables, GPS coax, BMS wire harness, RJ45 network cables.

I think what we got hung up on was the language of the ABYC which I now see that it must be read in context of the full section (11.17). The context is that the ground needs to be sized for the possible fault current (11.17.1.1). No possible fault current, then we can use the minimum ground wire size.

I now see the reasoning as similar to circuits within a house originating from the same panel: the light circuits do not need to have the same size ground conductor as a high current stove circuit as it is very difficult for a stove circuit to fault through a lamp circuit ground.

BTW, very good advice to place a battery disconnect switch in the thruster circuit in case the points weld on you!! We have done that and will use the procedure to turn off that system when we leave the boat.

Kristin,

There are a couple of different issues here. The thruster manufacturers may well want to see isolated ground systems, in which case this is the way to go and any charging devices (such as a B2B charger) need to also be isolated.

If instead all the batteries are tied together in a grounded system as you suggest, which is a very common installation, as you also note you have to think about what path the ground current will take for the devices powered by each battery, bearing in mind this will be back to the same battery to which the positive side for each device is connected.

It sounds to me as if the negative side of the various devices powered by your three battery banks is back to the battery via appropriately sized conductors. If this is so, the interconnection conductors between the battery negatives is essentially a non-current-carrying conductor which is there solely to maintain the batteries at the same ground potential.

Based on the ABYC and ISO standards the minimum size for this is 8 AWG (10mm2) unless the boat has a lightning protection system, in which case it is 6 AWG (16mm2). Of course, something larger is not a problem.

Nigel

David,

That’s an old engine! I believe, discontinued in the 1980’s. The fact is it still running indicates what you have has been working. As you say, the Racor primary filter has presumably been doing pretty much all the fuel filtering. The 10 micron rating is close to the 7-10 micron secondary filter rating often recommended for engines of this era. So long as you keep the tank clean and keep up with filter changes I would say you are good to go.

Nigel

David,

Yes, anyway to get a sample from the bottom of the tank works.

Nigel

David,

Thanks for this. I don’t know anything about these ‘enzyme treatments’! If you can find information and share it that would be great!!

Nigel

Jan,

I assume the batteries are in parallel. Yes, it would be better to have negative and positive busbars with equal length conductors to each busbar but absent that you can do what you propose, which is to put the positives on the terminal at one end of the paralleled batteries and the negatives at the other end but in this case all those conductors need a main fuse with a high AIC rating.

I am guessing you already have a positive busbar or terminal post or connection (maybe the battery switch) to which the positive feeder from the paralleled batteries goes and a similar negative connection point. If you have a main battery fuse (high AIC rating) in the conductor to the positive connection point, anything after this only requires branch OCP so this would be a better place to wire in the solar and hydrogenerator.

Nigel

Rich,

The presumption is the lighting will try to take the most direct path to ground. Bends and loops will increase the risk of side flashes, especially if there is some other grounded object in the vicinity.

Nigel