Small fuse box for direct to battery supplies e.g bilge pumps

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fergycool

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I dislike having multiple leads hanging off the battery terminal. So in a fit of organisational frenzy I have just moved three bilge pumps direct to a small blade fuse box. The fuse box is connected to the supply side of the main isolation switch and labelled as such. The cable is 25mm2 and protected by a 100mm fuse close to the battery terminal.

Now I only have the main supply and the battery charger attached to the +ve terminal.

Except now I worry that I've done something wrong as you rarely read about such wiring setups.

Every part of the cable is protected by appropriate fuses.

What do you think?

Cheers
Chris
 
fergycool said:
I dislike having multiple leads hanging off the battery terminal. So in a fit of organisational frenzy I have just moved three bilge pumps direct to a small blade fuse box. The fuse box is connected to the supply side of the main isolation switch and labelled as such. The cable is 25mm2 and protected by a 100mm fuse close to the battery terminal.

Now I only have the main supply and the battery charger attached to the +ve terminal.

Except now I worry that I've done something wrong as you rarely read about such wiring setups.

Every part of the cable is protected by appropriate fuses.

What do you think?

Cheers
Chris
Click to expand...

You mention 100mm fuse? Did you mean 100mA

You should, might be better, considering the rating - Amps and time charachteristics - fast, slow of the fuses, rather than the physical size.
Many different ratings of fuses come in the same physical size

Or have I got the wrong end of this?
 
Dammed auto correct (or actually my typing!). It's a 100 AMP megafuse. It's very close to the battery +VE terminal in the main domestic supply cable.
 
Sounds perfectly sound to me, if I've understood the description right.

My setup is quite similar - the connections from the service bank are:

- 240v charger
- Smartbank relay that parallels the service bank and engine battery for charging
- Main battery switch (turned on when arriving at the boat, turned off when packing it up). There is a Megafuse in this connection, right next to the battery terminal.

From the main battery switch, the service supply runs across the boat through a watertight conduit in the bilge, and up to the main electrics panel by the chart table. There's a fusebox there with the various circuits branching off, but only some of them are brought out to the front panel as switches. Some are simply fused, and live whenever the main switch is on, because the equipment on the end has its own switch.

Back on the same side of the boat as the batteries, there is the fridge compressor, the bilge pump, and the gas alarm. The former two draw significant power, and would not have a switch at the chart table (the fridge has a controller in the galley, the bilge pump has a switch by the companionway). So it seemed counterproductive to run their supplies across the boat and then back again, just in order to have their fuses in the same box as the others. The fridge compressor in particular is right next to the battery bay; running it from the main fusebox would need much thicker cable to prevent volt drop. So these two are powered from a 4-way blade fuse box (the main box is also blades) in the battery bay, and once that's there then the nearby gas alarm might as well run off it as well.

There is a small plaque next to the main fusebox stating which circuits are fused elsewhere - as well as the battery bay box, the Seatalk instruments are fused inside the autopilot control box in the aft cabin. That might fox anyone other than me for some considerable time if the label wasn't there!

Pete
 
Thanks! That does lead me to think I could also run my fridge of this new box. Currently that is lead from the main fusebox, but turned off when the domestic isolator is thrown. Let me think about that!

Cheers,
Chris
 
fergycool said:
Thanks! That does lead me to think I could also run my fridge of this new box. Currently that is lead from the main fusebox, but turned off when the domestic isolator is thrown. Let me think about that!
Click to expand...

Ah, hold on - is your auxiliary fusebox live all the time? I interpreted "supply side" of the switch to mean the downstream, switched side - "supply side" as opposed to "battery side" - seems like I have misunderstood.

That's different to mine, where the small fusebox is after the switch and so only on when everything else is.

Fair enough if you're running bilge pumps from it and want them to be on all the time. But I'm not sure I'd connect the fridge upstream of the switch.

Pete
 
nigelmercier said:
Where did you get a blade fuse box with a single input that will accept 25mm² cable?
Click to expand...

My main fusebox would fit that description; think it's a Blue Sea one. I have the 12-way, no negative busbar, single-input version, but they do a range.

My small fusebox is a simple row of blade holders in a plastic block, with individual spade terminals, but I don't need to run 25mm² to it.

Pete
 
nigelmercier said:
Where did you get a blade fuse box with a single input that will accept 25mm² cable?
Click to expand...

I'm afraid that I didn't.....!

It's got a M5 bolt with a flat metal contact. The 25mm2 cable has a M8 crimp on connector. Although the bolt is too small, the connector is held fully flat against the metal. I could only find stainless steel washers to ft above the nut, so when I get some copper or steel ones it will be held better.

Not a professional solution but OK I think.

Incidentally the main blade fuse boxes I have fitted do take 25mm2 cable. "Blue Sea - Systems 5026 St Blade Fuse Block"

http://www.amazon.co.uk/dp/B001P6FTHC/ref=pe_385721_37986871_TE_item


Cheers,
Chris
 
prv said:
Ah, hold on - is your auxiliary fusebox live all the time? I interpreted "supply side" of the switch to mean the downstream, switched side - "supply side" as opposed to "battery side" - seems like I have misunderstood.
Pete
Click to expand...

Sorry, am I using the wrong terminology? I thought "Supply side" = "Battery side" as opposed to "Load side", which is on the other side of the isolator switch.

Yes this fuse box is permanently live, although obviously fused.

Cheers,
Chris
 
I have the same and a second one, which has a relay off the alternator light, so the second box is always live when engine is running.....connected to the inverter, cabin blower and fridge (via zener)...so these items are always on with engine.


fergycool said:
I dislike having multiple leads hanging off the battery terminal. So in a fit of organisational frenzy I have just moved three bilge pumps direct to a small blade fuse box. The fuse box is connected to the supply side of the main isolation switch and labelled as such. The cable is 25mm2 and protected by a 100mm fuse close to the battery terminal.

Now I only have the main supply and the battery charger attached to the +ve terminal.

Except now I worry that I've done something wrong as you rarely read about such wiring setups.

Every part of the cable is protected by appropriate fuses.

What do you think?

Cheers
Chris
Click to expand...
 
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