Where to fuse??

[Dufour4800-175]

Hello,

I recently starting to thing about rewiring my boat. Im a bit confused on where i have to put fuses to make a safe installation. Now I have a starting batt. And 2 6v batt. For house bank. I have a wire going to the dc pannel, and then all dc sources are fused individually. Do i have to add some fuses? Probably one to protect the wire coming out of the batteries?

[skipmac]

I think the best option is to use a fuse right on the battery terminals, like the Bluesea systems fuse blocks. The cables to your DC panel attach to the fuse block so you are protected right to the battery. You can get single and double blocks and different rated fuses up to 200-300 amps.

[Dufour4800-175]

Thanks for this answer im gonna look that way!

[skipmac]

Here's links to the battery fuse blocks, single and double versions.

Blue Sea Systems Terminal Fuse Block

Blue Sea Systems Terminal Fuse Block

The single fuse photo is the bare connector. The photo on the double connector block shows the fuses installed.

Here's a link to the fuses. They come in lots of amp ratings.

Blue Sea Systems Terminal Fuse

[rebel heart]

My wiring looks something like this:

(starter battery)---->(starter bus bar)
(house batteries)---->(house bus bar)

I don't have a switch to switch the starter motor from the starter battery to the house; I don't need it and if I ever do it would take 30 seconds to unscrew a wingnut. Anyway, I have two fuses:

1) Between the starter and the starter bus block, rated at 150 amps. My starter motor says it takes 125 amps. So if I hit 150 (thermal), there's a serious problem.

2) Between the house bank and the house bus block, rated at 100 amps. Theoretically I could max that out if I was transmitting on the SSB at the same time somone was flushing the toilet at the same time someone was running a heat gun off the inverter. The odds of all that happening are obviously pretty slim.

Anyway, that's how I have mine fused. All the smaller circuits are run through the breaker panel, so every circuit is fused or or circuit breaker protected.

While you're doing all of this, consider putting a smoke (not co) detector in the battery compartment itself. If there's a fire in there it will be fully involved before the smoke will get out into the cabin. Cheap $20.

[Dufour4800-175]

thanks for the links!
And good idea for the smoke detector!

Im ordering fuses tonight!
Alex

[scoobert]

i may take heat for this, but do not use a fuse on your bilge pump.
run direct to the battery. no fuse at all.

[skipmac]

Originally Posted by scoobert

i may take heat for this, but do not use a fuse on your bilge pump.
run direct to the battery. no fuse at all.

Very bad advise. If the bilge pump jams from a small piece of debris it can overheat and start a fire.

DO fuse the bilge pump, always!

What you should do is run at least one bilge pump directly to an always hot connection, even directly to the battery so you will not inadvertently turn off the bilge pump when you turn off power at the main switch or DC panel. Just make sure that direct connection is fused!

[Sailmonkey]

Originally Posted by scoobert

i may take heat for this, but do not use a fuse on your bilge pump.
run direct to the battery. no fuse at all.

Always fuse a bilge pump, but size the wire and fuse properly so the running of the pump does not blow the fuse.

[skipmac]

Here is a quote from a previous thread about fuses for bilge pumps here http://www.cruisersforum.com/forums/...tml#post745764. I assure you Charlie knows what he's talking about.


During seminars, I will deliberately overfuse a small Rule centrifugal pump, jam the impeller with a screwdriver and then apply power and continue the lecture. Within about 10 to 15 minutes the pump starts to smoke. NOTE: THE FUSE NEVER OPENS DURING THIS DEMO! And this is why marine equipment manufactures are required to provide the fuse rating for their rotating equipment.

Here is the applicable section from the ABYC E-11 Standard:

11.10.1.2.1 Motors and motor operated equipment, except for engine cranking motors, shall be protected internally at the equipment, or by branch circuit overcurrent protection devices suitable for motor current. The protection provided shall preclude a fire hazard if the circuit, as installed, is energized for seven hours under any conditions of overload, including locked rotor.
NOTES:
1. It may be necessary to use thermally responsive protection devices on the equipment or system if the motor is not capable of operating continuously at maximum possible loading.
2. It may be necessary to test as installed in order to assure compliance with the locked rotor requirement. Voltage drop, due to wire size, and delay characteristics of the overcurrent protection device may have to be adjusted to protect the motor.

In the case of the Rule 500, if it was a 12VDC model, the technical specification is to protect it with a 2.5A fuse or circuit breaker. Rule 500 > ITT Flow Control - Engineered for life.

There is generally a lot more to this stuff then meets the eye.

Charlie will now relinquish his soapbox.

Hope this helps.
Charlie
__________________
Charlie Johnson
JTB Marine Corporation

[Dufour4800-175]

Okay!! Thanks for the replys! I now have to install fuses and do some testing!

[Yeti]

Battery Bank Fusing Photo Gallery by Compass Marine at pbase.com

The above is a great little article on the subject of battery fusing. Covers it really well.