Wiring cabin lights in Serial

[Hartley18]

Originally Posted by Rockter

I have a Russian motorcycle, and I wish the wires worked evey now and again.

Right now they work every once in a while and blow fuses nearly all the time.

Thicker wire would just tempt me to hang myself with it.

A Russian motorcycle, huh?? Hmm... You sure they actually used wire?

I thought that russians often used whatever they could find nearby!

[sailaway21]

I hate in-line fuses as a practical matter; they're a pain to secure properly with the wire and then easily access their contents. I much preferred it when most components came with the fuse incased in the back panel of the component,

That being said, it should be emphasized that they, or a suitable replacement for them are necessary. You can install a breaker or fuse for each circuit not to exceed that required by the wire and thus protect the wire, while doing nothing to protect the component. If you have a seperate circuit for each component, there is nothing wrong with having 12 gg wire with a 1 amp fuse reflective of the component's requirements. If, as is common, you're to have multiple components coming off the same circuit, the fuse should be of a size reflecting that of the lowest rated component. Since that practise results in the lowering of the utility of that circuit, ie..how many things you can place on it, it's perhaps best to fuse or size the breaker for the wire and fuse each component seperately at the component.

Anotherwords, Don't cut off those in-line fuses and throw them away without planning for adding similar fusing capability elsewise in their replacement! Remember that the tendency will be, when confronted with a single fused circuit, to apply a larger fuse at some future date, thus jeopardizing all unfused componnents down line.

[sailingdog]

One other thing you should do... if you're going to use in-line fuse holders, you really should make all the in-line fuse holders use the same type of fuse so that you don't have to carry different types of fuses on-board. I prefer to use the ATO/ATG type mini-blade fuses.

Anotherwords, Don't cut off those in-line fuses and throw them away without planning for adding similar fusing capability elsewise in their replacement! Remember that the tendency will be, when confronted with a single fused circuit, to apply a larger fuse at some future date, thus jeopardizing all unfused componnents down line.

[TrueBlue]

If installing new circuit overload interupters in your boat's DC system - why use fuses? Most modern boats are equipped with circuit breakers - even my 20 year old Nauticat had them - not one fuse onboard.

[Hartley18]

Another thing to bear in mind (and something most people forget) when dealing with 12V circuits on a boat is that batteries can deliver *large* amounts of current under short-circuit conditions - many hundreds of amps for a very short time. This is far more than you'll ever get out of a shore power connection without tripping something on-shore first.

Apart from the risk of fire on board from melting wire insulation (the obvious one), a more insidious problem is that high DC currents cause magnetic fields that will tend to push +ve and -ve wires apart (usually seen as "wire jump"). These forces are pretty impressive and can crack bulkheads wires pass through, force wires partly out of terminal blocks and damage the batteries themselves, so it's wise to check the entire run back to the battery if ever you accidentally short something out.

To stop this, a good practice is to fit a fuse or circuit breaker to the battery itself (like those fitted to cars for the same reason). These fit on one of the battery terminals and, rated to the maximum current of your house power, will limit the amount of accidental welding you'll do whilst fiddling with the wiring with the power switched on...

[Freesail99]

To stop this, a good practice is to fit a fuse or circuit breaker to the battery itself (like those fitted to cars for the same reason). These fit on one of the battery terminals and, rated to the maximum current of your house power, will limit the amount of accidental welding you'll do whilst fiddling with the wiring with the power switched on...

Do you have a link to show what it looks like ?

[Hartley18]

Originally Posted by Freesail99

Do you have a link to show what it looks like ?

They look like this, but this one is some bizzaro 3-way thingy. For this type, you specify what fuse rating you want from about 50 amps up.

I know I've seen single resettable circuit-breaker ones around someplace (I thought Whitworths used to sell them) but in this case Google has failed me.

[sailingdog]

TB-

This only works if you've got enough space to have individual circuits for each piece of equipment. If you have to gang multiple pieces of equipment on a single breaker, which is often the case... you really want to have fuses in-line for each piece of equipment.

Originally Posted by TrueBlue

If installing new circuit overload interupters in your boat's DC system - why use fuses? Most modern boats are equipped with circuit breakers - even my 20 year old Nauticat had them - not one fuse onboard.

[Hartley18]

Originally Posted by sailingdog

TB-

This only works if you've got enough space to have individual circuits for each piece of equipment. If you have to gang multiple pieces of equipment on a single breaker, which is often the case... you really want to have fuses in-line for each piece of equipment.

SD, you can get some pretty small 'in-line style' circuit breakers these days so size is not really an issue. Circuit-breakers also inherently tend to be more reliable than fuses - because there's no fuse wire to go high resistance on you! (yes, I've had it happen). And it doesn't matter how many times they trip (within reason) they can be reset very quickly... but once they fail, if you're well out of sight of land on a dark night, you're stuffed - unlike a fuse where you can just pop another one in.

The above notwithstanding, fuses are simpler, way cheaper and far less bother for most people so they do still have their place on anything other than some luxury cruiser. Each to their own.

A Point of Trivia of No Relevance To This Thread: Most fuses (all that I've ever known, anyways) are not designed to blow at their fuse rating but at some figure above it instead. eg. a 2A fuse will hold 2 Amps forever, but will blow quite happily at 3... but a 2A circuit breaker OTOH will trip just above 2 amps.

[Rockter]

The Russky bike does not have circuit breakers.
It behaves like it does though.
They are breaking all the time.