Hard to find...

Catfishmonkey

Petty Officer 3rd Class
Joined
Jun 6, 2010
Messages
97
Hey guys,

I need a 2.5 amp fuse for a bilge pump which calls for that size, but cant find it locally. Think I could use the 3 amp ones I got in the garage? Would that be a no-no?
 

Boatist

Rear Admiral
Joined
Apr 22, 2002
Messages
4,552
Re: Hard to find...

A 3 amp fuse would be fine. A 3 amp fuse sounds low to me.
Are you sure it needs a 2.5 amp fuse or does it draw 2.5 amps?
What size and brand bildge pump is it?
I am gessing 500GPH that draws 1.9 amps.
What type fuse is it? Radio shack has a 2.5 amp fuse for the 1 1/2 by 1/4 inch round fuse.
The new Blade type auto fuses I would check with Some place like Napa Auto Parts.
 

Catfishmonkey

Petty Officer 3rd Class
Joined
Jun 6, 2010
Messages
97
Re: Hard to find...

I believe it is this one Tsunami 500 GPH Cartridge Bilge Pump, 12VDC (Attwood). I think it draws 1.5 amps. So they call for 2.5 amp fuse. Guess 3 amp would be fine though, right? It is one of those long, tube like, marine fuses...or that is what I am thinking anyhow. doesn't have a built in fuse holder...going to rig it with one of those inline fuses.
 

TerryMSU

Senior Chief Petty Officer
Joined
Jul 31, 2007
Messages
743
Re: Hard to find...

Smart move using the inline cylindrical fuse. I suspect that it will work much better in a marine environment. The 3 amp will rpobably be OK, but it really depends on the wire size that you used. Using a slow blow fuse is probably better, as it will not blow on the surge that the pump motor will draw at start-up. Based on the following link, http://www.powerstream.com/Wire_Size.htm I find that the difference between 2.5 to 3 amps is only about 1 wire size. The following WIKI is more leinient for wire size. http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity

Your wire will often have the current capacity printed on it. If so, I would personally recomend a 2 to 1 safety factor. So if your wiring says 6 amps maximum, you are probably safe. (Note: this is just my best guess, so if someone knows better and says not to go up to the 3 amp fuse, then I would not argue with that person.)

TerryMSU
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Hard to find...

It won't be wired with anything lighter than 16g, which can safely handle about 8 amps. a 3 amp fuse would be fine.

The fuse just protects the wiring. It smokes instead of the wiring.
 

Catfishmonkey

Petty Officer 3rd Class
Joined
Jun 6, 2010
Messages
97
Re: Hard to find...

Ok sounds good. While we are on the topic, do you think it would be ok if I wired everything with say, 12 gauge (dont really want to buy different spools if I can avoid it). I got a fishfinder, a horn (calls for 8 amp fuse), running lights (bow and stern; what kind of fuse you think I would be safe to use for this...lights are vintage, so I have no idea), and that's about it for now. What is the lightest I can get away with? Also, the info on the fishfinder and bilge pump says that I should try to wire directly to the battery, instead of to a breaker. What are your guys thoughts on that? Gonna need a whole lot extra wire for that.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Hard to find...

If you wire directly to the battery, you still need to install either a fuse or a circuit breaker. If wiring shorts out and the battery is good, the result is a fire. Separate fuses are OK. So is a good fuse panel wired right, mainly heavy conductors to the battery.

Normally, 14G can be fused up to 15 amps, 12 G will handle 20 amps. 10G 30 amps. In low voltage you have to derate for long circuits. I doubt that you have any load over 15 a.
 

Catfishmonkey

Petty Officer 3rd Class
Joined
Jun 6, 2010
Messages
97
Re: Hard to find...

Right, of course. I was going to put multiple fuses. Is a fuse panel necessary in that case. If I just go direct to all of these devices, what gauge wire would be good enough? 14?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Hard to find...

Nearly every circuit on a boat can get by nicely with 16 gauge wire. 12 gauge is heavy, expensive, and totally unnecessary. Fuse selection depends on the total current draw in the circuit it is protecting. You need to look at your accessories, add up whatever you have on that circuit and fuse accordingly. Only high-current draw items like high power stereos, trolling motors, big spot lights, etc, need bigger wire.
 

Catfishmonkey

Petty Officer 3rd Class
Joined
Jun 6, 2010
Messages
97
Re: Hard to find...

I figure going with individual fuses for each item (bilge pump, fish finder, lights, horn), and wiring each one of these directly to the battery, straight. Figure I will get 14 to 16 gauge wire...whatever I can get a deal on. Would that work?
 
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