Two Fuses?

[JDCAVE]

I’ve had a new Furuno Sounder installed. It comes with inline fuses on both the (+) and (-) leads. My old one was fused with a single fuse on the (+) lead in a fuse block. What is the rational for this new development?

Jim

 

[psneeld]

I was told it was to protect from incorrect hookups (reverse polarity).

Icon radios used and maybe still do the same.

 

[Ka_sea_ta]

I don't know for a fact but my best guess is if the case becomes energized from an external source it will protect the ground wire from frying... This is along the same vein as the inverter case bonding wire has to be the same or one size smaller then the size of the DC supply cables.... it's a small price increase for reducing chance of fire


After posting this: Reverse polarity protection while commonly done with diode, doing it with a fuse would eliminate a lot of warranty returns for replacement of the rp diode

 

[O C Diver]

I was told it was to protect from incorrect hookups (reverse polarity).

Icon radios used and maybe still do the same.

Yes, and this isn't new. This has been done for more than 20 years. What is new, is that the fuse is external. Many pieces of electronics had the second fuse internal on the power supply board, necessitating a trip to the dealer if you wired it reverse polarity. 20 years ago, grounding wires tied to the bonding system were very common on marine electronics. Most bonding systems were tied to the DC negative.

Ted

 

[ghost]

Reverse polarity is typically protected with a diode. There are floating dc power supplies, but I’m still at a loss to guess why a fuse on the negative would be necessary. I think it’s because a floating dc negative can have a potential above zero, but I’m not really putting it all together.

I took about 3 of 4 years toward an EE before changing majors, so maybe that final year would have been worth it! Plus, I’m old enough to not remember that far back anyway.

 

[JDCAVE]

Possibly a belt and suspenders thing. The Icom radio I installed neither provided this or called for a fuse on the (-) lead.

 

[psneeld]

Standard HF DC Power Cable for IC-706 and other HF rigs


And the second.......

Power Cable for FM Radios fits Powerwerx DB-750X, Yaesu, Kenwood & Icom
This DC power cable is 9 ft. long 14 AWG. The OEM "T" style connector is the power source side and mates with many FM radios. Inline glass AGC style 15A fuses on both sides offer circuit protection. Connect to your power source with bare copper wire.