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Mjlee1985

Where to fuse?

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Mjlee1985

Adding a second battery under the observation seat along with moving existing battery and switch. 3 amps running off of a fused distribution block then into the switch common post (perko heavy duty dual battery) . Power from motor into common and main boat power into common post. Then second battery off the 2nd post. What and where do I fuse all these wires?

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nyryan2001

You need to fuse both ends of the + wire that runs from the perko to that 2nd battery.

ABYC says it needs to be within 6".

So that means you need an appropriate sized fuses on the + line.... within 6" of the perko AND within 6" of it's connection to the + terminal on that second battery. 40a-60a fuses on 2ga power cables is about right.

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Earmark Marine

Adding a second battery under the observation seat along with moving existing battery and switch. 3 amps running off of a fused distribution block then into the switch common post (perko heavy duty dual battery) . Power from motor into common and main boat power into common post. Then second battery off the 2nd post. What and where do I fuse all these wires?

The fusing is for protection of the boat and boat occupants in the event of a boating accident for example. The following is only customary.

Most will fuse/breaker the helm buss and all audio equipment as close as possible to the battery, in other words, every supply except for the alternator/starter feed. Once you add the second battery and dual battery switch this is usually moved close to the switch common out....provided the dual batteries and switch are in very close proximity to one another. Distance means exposure and that is where you have to assess the risk. Certainly, a remote mounted second battery should have a fuse/breaker at both ends of the link.

David

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MLA

A typical starter motor can draw 200-300 amps, so if only a 60A fuse was in-line on the house bank, it could not be used as backup starting battery. The circuit protection needs to be of a size that will carry the potential loads, yet not exceed the capacity of the cable its protecting.

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Murphy8166

Do our boats have some sort of crcuit protection for the engine to perko? It is a long 2/0 run

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nyryan2001

MLA- I have 3 SRM29s remoted 20ft to stern with Kicker 60a fuses on 2ga. No issues, used them to start before.

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racer808

Now I am confused. I need to have a fuse on the positives from the perko to both batteries as well as the positive to the helm? And an inline fuse on amplifier positives with-in 18" of the battery or the amp? Everything is my passenger compartment.

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Earmark Marine

Now I am confused. I need to have a fuse on the positives from the perko to both batteries as well as the positive to the helm? And an inline fuse on amplifier positives with-in 18" of the battery or the amp? Everything is my passenger compartment.

Not at all. Ryan did the correct thing for his particular situation. Yours is diffenent.

Between the Batteries and Perko? Not reqiured if all are in the immediate proximity and the Perko is correctly positioned.

Between the Perko and helm buss? Absolutuely. That is a very long (often 6-gauge) cable. The breaker/fuse should be very close to the Perko.

Between the Perko and audio amplifiers? Yes. And close to the Perko.

There is also a standard where you redundantly fuse any junction with separate fuses after the division where you have a step down in cable size. However, I don't subscribe to that if the distribution blocks are immediately on top of the amplifiers. The distance is so short that the risk is very small relating to a boating incident. On the other hand, if the distribution block is at the Perko end then I would use a fused distribution block. In any case, you need to have a master breaker/fuse in one form or another for the collective amplifiers right at the supply side.

Some will use redundant fusing when the distribution is at the amplifiers. Again, with such short extensions, there is little exposure and little risk. But that fusing is generally used in consideration of the amplifiers, if they do not have their own fusing or do not have a sophisticated protection circuit.

Past the requirements given so far, I wouldn't add any unnecessary components that add many more connections, terminations and resistance.

David

David

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Mjlee1985

Ok so both the battery's are going to be in the observation seat area. Short runs. So fuse the 0 gauge wire running from the perko to the stereo battery then fuse the 0 gauge wire running from the common post of the perko to the fused distribution block? Then also fused between the 0 gauge running from the perko to the starting battery and then also fuse the wire( not sure what gauge) going to the helm?

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