HDS units popping 3 amp fuse

I need some electrical help with my HDS units.

Here is how i have it wired.

From my 12 volt battery, I routed one positive (with the 3 amp fuse block supplied by lowrance) and one negative to a new fuse bus up under my dash. The battery has nothing else on it. I then conncted a HDS 8, LSS-1 , HDS 7 , LSS-1 each individually to the bus. Each one also has its on fuse at the bus. The problem is that when i have them all on i occasionally pop the 3 amp fuse at the battery. It has happened 5 times. Any feedback would be much appreciated.

Am I reading correctly that you have a single run with a 3amp fuse, that feeds 3 devices, that each have 3 amp fuses?

I dont think 1 3amp fuse could handle all that. I would put a 10 or 15 amp breaker at the Bat to protect wires and use the individual fuses for each unit close to the unit.

What size wire is at the battery that supplies power for you units?

The size of the wire is important. You need to match the fuse to the size. How to Determine the Fuse/Wire Size for YOUR Project

The wire size is 12. bigger than the wire size of the fuse holder

Quote:

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Originally Posted by mduncan62

Am I reading correctly that you have a single run with a 3amp fuse, that feeds 3 devices, that each have 3 amp fuses?

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There are 4 devices

A 3a fuse is too small for all the units. You need a large feed wire and a 5 to 7a fuse to feed the bus.

I would use 15A fuse then. You can add another 3A device without replacing the main fuse. The fuses protect the wire, not the units.

Quote:

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Originally Posted by Cane Pole

I would use 15A fuse then. You can add another 3A device without replacing the main fuse. The fuses protect the wire, not the units.

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Yup!

Yeah, the fuse for the bus should match or exceed the max by a little, then fuse all the units. As it is now, you are trying to cram 12amps in a 3 amp bag.

I wouldn't go that big with the fuse. The units only draw about an amp each, so 7 or so ought to cover you. Fusing too large means you need large wire. The fuse in the block is not needed. You really need a fuse in the wire near the battery to protect the wire run to the front.

I thought you were "home run" fusing at the battery, not at a distribution point.

My boat came from the factory with a 10ga 20 amp fused wiring for accessories.

On my HDS unit's I ran a separate positive and negative wire for each unit to the main battery with each positive lead having it's on 3 amp fuse with the correct wire size.They are not tied into any thing else.No problem's.

Quote:

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Originally Posted by CatFan

I wouldn't go that big with the fuse. The units only draw about an amp each, so 7 or so ought to cover you. Fusing too large means you need large wire. The fuse in the block is not needed. You really need a fuse in the wire near the battery to protect the wire run to the front.

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Thanks to all for the feedback. Obviously im not a electrician. I'm a little better at Crappie fishing but not much. Anyway, it sounds like im protected at the bus becasue i have each of the units fused there. My issues is not enough fuse for the #12 wire going from the battery to the buss. I have a 20amp fuse that automatically resets it self if tripped. Is that too big?

Determining Fuse Size.

The question of determining fuse size has been a common one lately so we decided to make a quick write up on choosing the correct fuse size. One common misconception about choosing the correct fuse size is that it’s dependent the load of the circuit. Actually, the load of the circuit should have nothing to do with choosing a fuse size. The fuse size should be based on the SMALLEST wire (largest gage number) in the circuit. Here is how to correctly choose the right fuse size for your circuit.

1) Determine the wire gage you already have by locating it on the package or measuring it, you can also look at the topic this was posted in on Oznium forums for a step by step guide to finding the amperages for common products at the Oznium store.

2) Use the following table to determine the maximum current for whatever wire gage is being used.


http://i146.photobucket.com/albums/r...rams/Table.gif

3) Take the maximum current value obtained from the table and find the largest fuse you can find that still falls within the limitations. DO NOT EXCEED THE VALUES ON THIS TABLE! Common automotive blade-style fuses exist at 5A-20A in 5A Increments. Ex: 5A,10A,15A,20A