In-Line Fuse?

[PubUltraStar]

I've already picked up a fuse panel by Blue Sean systems to connect all my electrical nonsense in my teardrop, like fantastic fan, interior lights, 12V recepticle, etc. I also have a master switch to connect in between the fuse panel and the battery. It recommends putting an in-line fuse as well, and I've seen some diagrams on this forum that reference it. Just wondering how big of a fuse I need. The fuse panel directions say that it should be a Max of 125 amps. Any recommendations, or know how I should calculate the proper fuse between the fuse panel and the master switch and battery?

Also, if you have recommendations on part numbers, or brands, that would be appreciated.

[halfdome, Danny]

Others may disagree... but I see no reason for the inline fuse to the Blue Seas fuse panel, if you have a battery kill switch.
The Blue Sea fuse panel is a great product & I've used several in this manner.
I also have a kill switch on each of my two batteries.
I have a 15 amp breaker box for my 110 volt along with a GFCI plug.
Danny

[Greg M]

As a former car stereo installer I feel an inline fuse is good, cheap, insurance and is a necessity. Should the input line short before the panel, or if you draw too much current from the various branch circuits at once, it can prevent a fire. While it seems unlikely to happen, I have had this kind of short occur, and the fuse saved my bacon.
The fuse should be placed as close to the battery as practical.

[Optimistic Paranoid]

If Blue Sea says max 125 amps, that means the fuse panel ITSELF isn't rated to handle any more than that. The actual size fuse you put on the feed wire depends on the wire size. A 12 gauge wire should have a max fuse size of 20 amps. 10 gauge, 30 amps. 8 gauge, 50 amps. 6 gauge, 80 amps, and 4 gauge, 125 amps.

As for brands, Blue Sea itself makes a lot of different types of inline fuses, and they're all great quality.

Regards
John

[PubUltraStar]

Thanks for the replies. All good information.

[halfdome, Danny]

As a former car stereo installer I feel an inline fuse is good, cheap, insurance and is a necessity. Should the input line short before the panel, or if you draw too much current from the various branch circuits at once, it can prevent a fire. While it seems unlikely to happen, I have had this kind of short occur, and the fuse saved my bacon.
The fuse should be placed as close to the battery as practical.

I started thinking of what you said Greg. I use 4 gauge wire and couldn't find an inline fuse for it locally.
All that's offered locally is for 12 gauge wire and didn't feel it would be adequate.
After a search I see these are available on EBay so I'll be doing some retro fitting on my teardrops.
You just screw the stripped wire into the fuse holder.
Danny

[Greg M]

Happy to help Danny, just head down to your local Car Toys.
I can't tell you how many burned up wires I replaced because some DIYer didn't fuse the battery.
It's less a problem with a trailer, but I should also mention that you shouldn't connect the ground wire directly to the battery. Ground to the chassis so that when your ground strap at the battery end comes free of the chassis you don't have all the current of all your devices trying to go through your stereo.

[eamarquardt]

.................but I should also mention that you shouldn't connect the ground wire directly to the battery. Ground to the chassis so that when your ground strap at the battery end comes free of the chassis you don't have all the current of all your devices trying to go through your stereo.

Many on the forum have found that using the trailer frame as the ground conductor isn't optimum and unreliable (if the connections aren't properly maintained). Better to ground each circuit directly to the battery/ground buss using the same gauge wire as on the positive side of the circuit. By the way, the positive side really supplies the electrons which are negatively charged so it should really be called the negative side. Go figure.

Cheers,

Gus

[halfdome, Danny]

Happy to help Danny, just head down to your local Car Toys.
I can't tell you how many burned up wires I replaced because some DIYer didn't fuse the battery.
It's less a problem with a trailer, but I should also mention that you shouldn't connect the ground wire directly to the battery. Ground to the chassis so that when your ground strap at the battery end comes free of the chassis you don't have all the current of all your devices trying to go through your stereo.

Car Toys??? No way, they want your life history, just to make a purchase .
I don't do business with companies like them.
Danny

[Greg M]

You can blame Mr. Rutherford for that one Gus. He arbitrarily named them that before even guessing at the existence of the electron. Don't forget the electrons themselves move quite slowly, it's the quantum effect that's truly propagating through the wires.

[eamarquardt]

You can blame Mr. Rutherford for that one Gus. He arbitrarily named them that before even guessing at the existence of the electron. Don't forget the electrons themselves move quite slowly, it's the quantum effect that's truly propagating through the wires.

A good discussion: http://io9.com/5546927/how-fast-do-elec ... wer-cables

A basic explanation: http://www.qrg.northwestern.edu/project ... -flow.html

But I'm not so sure that the electrons are flowing at the same speed everywhere in all circuits. Inductors and capacitors can put the voltage and current out of phase with one another and alter the flow of electrons over time through a specific point in the circuit: http://hyperphysics.phy-astr.gsu.edu/hb ... ap.html#c1 and http://hyperphysics.phy-astr.gsu.edu/hb ... nd.html#c1

All that said, your main battery wire should be fused for the maximum current you want (consistent with wire gauge) as close as possible to the battery. That will afford you maximum protection. A cutoff switch is a good thing but a cutoff switch alone isn't going to protect your wiring in the event of an overload.

Cheers,

Gus

[Bogo]

Ground wires should be equal to or larger than the supply wire. For large loads, > 10 Amps, you pretty much must run your own ground wire back to the battery (-) or a high capacity ground bus already connected to the battery (-).

[Breytie]

ALWAYS fuse the feeds from the battery, close to the battery. It is one of the cheapest form of insurance. On low current applications (<20A), use in-line fuse holders. On big systems use fusable links. Both can be found at auto shops. Rate them below your cable's maximum capacity or a little (10%) over the maximum expected current draw, whichever is lowest.