Fuse in ground wire.

[RT Firefly]

Greetings,
Recently whilst poking around in our "new" vessel I notice fuses in a couple of ground wires. I was always under the impression that only +'ve wires need be fused. One of the fused -'ve wires was from the onboard battery charger. Said wire was compromised so I replaced it and thus eliminated the in line fuse. Was I wrong in doing so? Is it common practice to fuse -'ve (ground) wires? Thanks.

 

[Fleming]

You're fine in removing it as long as you verify that the positive side has overcurrent protection. Not needed to do both, and ABYC says overcurrent protection should be on the positive side. Some European boats like to switch the negative side, but North American convention is all fuses, breakers, and switches in only the positive. Not harmful to have the negative fuse, but can make troubleshooting more difficult when both sides are protected.

 

[DavidM]

“Protected”, hmmm. Just like a fuse on the positive wire, any fuse on the negative wire has to be close to the battery to be effective. Any wire before the fuse has no protection.

David

 

[psneeld]

Agree that one or the other should be fused.

Not sure if they still do, but Icom radios used to fuse both.

Ahain not sure but believe it was for in case you got the wires switched, it protected something in the radio.

 

[RT Firefly]

Greetings,
Boat was built in Tarboro NC in 2015 so ALL American using the AYBC suggestion of yellow ground wires although the leads from the battery charger were black (-) and red (+). Radio is far removed from the wires in question and pretty sure it isn't Icom. Which reminds me. I noticed yesterday radio connection was a gob of electrical tape which I will clean up today. Thanks.
Edit: Radio is Standard Horizon.

 

[O C Diver]

I have two multiple bank battery chargers that have fuses on the positive and the negative for each battery bank. As I purchased them new, i assumed it was an ABYC requirement.

BTW, the title of the thead is very misleading. DC circuits have only positive and negative. I was trying to visualize a fuse in the bonding system.

Ted

 

[SteveK]

-negative wires fused from a multi battery charger actually makes sense to me. While the positive is directed to a specific bank, the negatives are all connected so any stray positive current could ruin a good charger.

 

[C lectric]

My radar , Furuno 1815 installed about 6 yrs ago, fuses both Pos and Neg power leads.
I scratched my noodle a bit before I realized they are international so they cover their tails by fusing both sides for use anywhere in the world.

Much of Europe used to use negative grounding. I would not want to bet that all of those countries have changed if they started with a neg. ground.

I used to be an electrician and between European and N.A. mfgrs. I saw other differences. EG: colour coding of single and three phase wire cables so we had to pay attention to what we were doing. It has been long enough now that I suspect Neg. fusing is no longer used at all but if done properly there is no problem with it as it did work and well.

May have nothing to do with it and far less likely now.

 

[Marco Flamingo]

The reason that I heard for not having a fuse in the negative is that whatever gizmo that the wiring powers (usually some motor) will likely be the cause of a short. It is possible that, as the gizmo starts to burn up, it finds it's own ground. Power would still be going through the short even if the negative wire fuse finally blows. Fuse on the + is the safer bet. Both + and - probably doesn't hurt anything.