wiring question- two fuse blocks

[jcb1977]

might be a dumb question but is there any concern with wiring two fuse blocks in series on the same fuse? see sketch below. I think 80 amp fuse will be more than enough for everything i'm going to power on those two fuse blocks so not worried about that. Just not sure if it's acceptable practice to wire them in series. each fuse block is rated for 100 amps in total and max 30 amp per circuit.

 

[FSH 210 Sport]

Your drawing shows a parallel configuration, but you are relying on the tap point at the first fuse block to feed the second.

To answer your question it would be bad if you wired them in series.

I would not do it that way. I would put in two buss bars, one positive and one negative, like your common ground, and run a dedicated positive wire from the positive buss bar to each fuse block.

Consult this wiring ampacity chart for your fusing. https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

Looks like 80A fuse might be high for what you are doing or you will need to up the conductor size to #2 AWG depending on what your power draw will be and or the length of the run to compensate for voltage drop.

 

[jcb1977]

Your drawing shows a parallel configuration, but you are relying on the tap point at the first fuse block to feed the second.

To answer your question it would be bad if you wired them in series.

I would not do it that way. I would put in two buss bars, one positive and one negative, like your common ground, and run a dedicated positive wire from the positive buss bar to each fuse block.

Consult this wiring ampacity chart for your fusing. https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/

Looks like 80A fuse might be high for what you are doing or you will need to up the conductor size to #2 AWG depending on what your power draw will be and or the length of the run to compensate for voltage drop.

I thought about adding a bus bar- what's the concern with feeding the second fuse block from the first?

 

[Neutron]

How long of a run is this to each block? I am assuming that one is much further away from the second?
I agree with @FSH 210 Sport #2 awg would be a better choice for you and approximately how many amps are you using? You have a 12 circuit and 8 circuit. If you added it all up and its like 70amp then you should run 100 amp circuit not 80 amp.
"Do it once and right dont skimp on electrical" from my personal experience

 

[FSH 210 Sport]

I thought about adding a bus bar- what's the concern with feeding the second fuse block from the first?

You are relying on one tap point to run both fuse blocks, and that one tap point is a fuse block, all the current will flow through that one point, on a fuse block.

If it was me, I’d use a circuit breaker instead of a fuse to feed the two fuse blocks. If you ever have an issue you just reset the breaker.

This is how I did mine. https://jetboaters.net/threads/12-volt-accessory-buss-additional-switches.37156/#post-604853

All the protection are circuit breakers as the hots leaving the buss bar go to ckt breakers then feed the rocker switches.

 

[jcb1977]

so the 12-circuit fuse block is in the stern by the battery compartment....the 6-fuse block would be at the helm. Loads will be pretty small on each fuse block.

12-circuuit block currently has the radio (15amp), charter plotter (5amp fuse), bilge (3amp fuse), and main (20amp fuse). nothing else currently planned to be added to the 12-circuit fuse block in the stern.

The 6-fuse block i'm adding at the helm is for a mini-amplifier (RMS of 200watts so ~17 amps continuous). also will probably add a VHF radio and maybe some more USB chargers at the helm. so, figure 20-25 amps maybe at this fuse block.

 

[Neutron]

so the 12-circuit fuse block is in the stern by the battery compartment....the 6-fuse block would be at the helm. Loads will be pretty small on each fuse block.

12-circuuit block currently has the radio (15amp), charter plotter (5amp fuse), bilge (3amp fuse), and main (20amp fuse). nothing else currently planned to be added to the 12-circuit fuse block in the stern.

The 6-fuse block i'm adding at the helm is for a mini-amplifier (RMS of 200watts so ~17 amps continuous). also will probably add a VHF radio and maybe some more USB chargers at the helm. so, figure 20-25 amps maybe at this fuse block.

You will definitely want a 100 amp circuit breaker and #2 wire. Without adding anything you are at 70amps give or take. You should be around 80% load max on the circuit so if you add anything more even at 100 amps you will be on the high side. So 120amps if you are planning to add anything.
The long run to the helm will have voltage drop so you need a heavy gauge wire to compensate for this.

 

[FSH 210 Sport]

if the 12 ckt fuse block is in the battery compartment then I would run a lead from the battery to the 12 ckt fuse block, then run a separate conductor to the 6 ckt fuse block at the helm. Now you can run smaller conductors to each fuse block. I used #10 AWG wire to feed my buss bars which are under the helm with a 30A breaker.

 

[jcb1977]

if the 12 ckt fuse block is in the battery compartment then I would run a lead from the battery to the 12 ckt fuse block, then run a separate conductor to the 6 ckt fuse block at the helm. Now you can run smaller conductors to each fuse block. I used #10 AWG wire to feed my buss bars which are under the helm with a 30A breaker.

the other thing I can do is just run the mini-amp, vhf, and usb chargers off the 12-circuit fuse block. Was thinking if I'm doing all this, might be nice to have a fuse block up there for anythign in the future, but might be easier to just run smaller circuits from the stern.

 

[jcb1977]

You will definitely want a 100 amp circuit breaker and #2 wire. Without adding anything you are at 70amps give or take. You should be around 80% load max on the circuit so if you add anything more even at 100 amps you will be on the high side. So 120amps if you are planning to add anything.
The long run to the helm will have voltage drop so you need a heavy gauge wire to compensate for this.

your adding fuse sizes.....wouldn't you consider actual loads? actual loads are much much smaller.

 

[FSH 210 Sport]

I just posted this today.

https://jetboaters.net/threads/marine-circuit-protection-explained.43117/