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
Hi BlueMoon,
Electrons actually flow from neg to positive, and it doesn't matter where the fuse is in the circuit, so it kinda makes sense to me, but I defer to the electrical guru Seabreezers that are here.
It depends on how your boat is wired I would think, if the negative path for the circuit is individual and a fuse can be inserted neatly, I see no reason at all why this would be an issue.
Cheers,
SB
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.
Lest say you do put the fuse in the negative side (at the battery) and it blows.
The positive side of the battery is still connected (live) to all pieces of equipment in the boat that it runs to, including the equipment that blew the fuse.
Yep, positive by convention and for the common negative reason. No one else would expect a fused negative .
Cheers
Bristol
As mentioned earlier electrons actually flow from negative to positive, so fusing the negative side makes sense. Years ago some European car manufactures had body's earthed at the positive and everything else from negative side. However I would 100% only fuse the positive as this is common practice and keeps everything easy to understand and won't confuse anyone down the track.
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
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
Select to expand quotefishmonkey 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
Select to expand quoteSirJman 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.
Select to expand quoteTrek said..
I can understand a floating ground in a boat but not car 
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Select to expand quotefishmonkey said..Trek said..
I can understand a floating ground in a boat but not car
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Love it!!!
