Hi,
I am adding another battery bank to the boat to run a portable fridge & another bilge pump(manual switch, not with a float switch...probably). Solar charged only, and will keep it completely separate from the other house battery banks.
Someone told me its better to put the fuse block on the negative cable, & it does make sense in that its one less connector being used, (I usually put a blade fuse box just after the switch panel). Where as the NEG is going to a NEG bus bar anyway....might as well make that the fuse block too?
Apparently the Navy puts the fuses on the NEG.
Any thoughts?
Cheers

With DC it doesn't matter if fused in the pos or neg but is good practice to insert in the positive. In a lot of systems they ground the neutral eg.your car. In this case you must be in the positive. Fused negatives are a pain to trace faults.
You definitely don't want to mix and match on the same installation, pick a system and stick to it.
My advice is not to place the fuse in the negative.
PS 240VAC is a complete different kettle of fish. AC must be fused / switched in the positive and if there is a chance that the polarity could be reversed you must Switch / fuse both active and neutral. Hence anything that plugs in must be done this way. Eg. Your boat, caravan ect. But leave the 240v work to the experts.

Yep, positive by convention and for the common negative reason. No one else would expect a fused negative .

Cheers

Bristol

Although electrons flow from the neg, potential difference comes from the pos. A blown fuse on a neg could still have volts on the faulty device and may get current flow from an alternative grounded source.

I've never heard of fused neg except from some car situations where they are positely earthed.

I'm no expert, but if you had a steel boat, I'm thinking this could lead to electrolysis issues.

-jman

fishmonkey said..
the electrical terms "ground" and "earth" are actually misnomers when talking about boats and cars, since the electrical return path to the battery is not literally grounded or earthed.

mgaguru.com/mgtech/electric/et098.htm

I sort of disagree.

Yes with cars the ground or earth is floating on rubber tyres, poorly grounded. However boats often live on conductive salt water which is practically earth or ground. There has even been situations where poorly grounded boats have caused a spark jump when refueling, then kaboom.

Then when you start bringing AC inverters into the mix there is even more to talk about.

-jman

fishmonkey said..

SirJman said..

fishmonkey said..
the electrical terms "ground" and "earth" are actually misnomers when talking about boats and cars, since the electrical return path to the battery is not literally grounded or earthed.

mgaguru.com/mgtech/electric/et098.htm

I sort of disagree.

Yes with cars the ground or earth is floating on rubber tyres, poorly grounded. However boats often live on conductive salt water which is practically earth or ground. There has even been situations where poorly grounded boats have caused a spark jump when refueling, then kaboom.

Then when you start bringing AC inverters into the mix there is even more to talk about.

-jman

sure, it's easier to have a grounding-to-water fault on a boat, but the point is that the electrical system is usually designed like a car, with a floating battery return system, not a true ground/earth.

Grounding plate on the outside of the hull should be connected to your neg, not floating.

www.nmeaboater.com/content/newsm/news

I can understand a floating ground in a boat but not car

Trek said..
I can understand a floating ground in a boat but not car

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