Electrical Redesign Advice

[ozskipper]

I would keep the inline fuses. They are a good indicator of a problem component. If you had ten items on one circuit and blew the main breaker/fuse you wouldnt know what actually blew.

Yes, multicore cables make life simple and neater. As other have suggest there are colour codes to be adheared to though.

It would be sensible to create schematic diagram and keep it on board for when you forget what was wired with what colour. Labling each wire will also help.

The 12volt Doctors Practical Handbook is certainly worth the read..
The 12 Volt Doctor's Practical Handbook.



Heat may build up behind the panel. A couple of clam shell vents would allow airflow and heat escape at the top of the panel.

[Heart of Gold]

Originally Posted by StringBimini

Heart_Gold, thanks for the link. I will read it cover to cover. You aren't related to Neil Young are you?

Although I am a follower of the great man, I am not related and to tell you the truth, I named my boat after the wondrous craft in Hitch Hikers Guide to the Galaxy with the infinite improbability drive. As it turns out, the song suits her quite nicely as well. My admiral and I did search for her for quite a while.

Cheers

[goboatingnow]

I would keep the inline fuses. They are a good indicator of a problem component. If you had ten items on one circuit and blew the main breaker/fuse you wouldnt know what actually blew.

Inline fuses hidden behind panels, connection boxes and randomly spread through the boat are a receipe for disaster. At the very least change all of them to a consistent size. Best is group them together. Most manufacturers put in in-lines fuses to protect the internal wiring in the device. The electronics will always be protected by other electronics as fused cant save electronics.

In my case I remove them all.. ( but thats just me)

Dave

[ozskipper]

Originally Posted by goboatingnow

Inline fuses hidden behind panels, connection boxes and randomly spread through the boat are a receipe for disaster. At the very least change all of them to a consistent size. Best is group them together. Most manufacturers put in in-lines fuses to protect the internal wiring in the device. The electronics will always be protected by other electronics as fused cant save electronics.

In my case I remove them all.. ( but thats just me)

Dave

You cant change them all to a consistent size. Different items are rated at different currents loads. Therefore everyboat should carry an assortment of fuses. Else that Is the recipe for disaster.

Fuses save electronics every day in my business. They arent there just to stop fires. Yes a lot of them are rail fuses. But if the manufacturer puts a fuse there, its for a good reason.

[goboatingnow]

You cant change them all to a consistent size. Different items are rated at different currents loads. Therefore everyboat should carry an assortment of fuses. Else that Is the recipe for disaster.

The size of a fuse relates to its housing, the rating refers to its current protection. My suggestion was to standardise on one type of physical size, which removes the needs to carry a huge assortment of different sizes. some of which are hard to find.

Fuses save electronics every day in my business

No mechanical device, which is what a fuse is , can ever "save" electronics, if you look at the failure modes of semiconductor junctions you will see that.

The reason electronics manufacturers put in fuses ( and I should know its was my job for years as a design engineer), is firstly the design engineer will design the electronic circuit to withstand overloads, ie PSU circuits will handle have reverse protection, crowbar circuits, current foldback etc, driver circuits will be protected from short circuits etc. Then and only then the fuse "might" blow. Whats protecting the electronics is the "protection electronics" its never the fuse. The fuse is there to ensure that overloads in the internal wiring etc or prolonged fault currents ( that protection electronic are handling) ultimately blow a fuse and remove the fault condition.


for example I once design a industrial high frequency motor control, ( basically an invertor), 70% of the circuit was protecting various parts of the 30% actually doing the work.
Dave

[ozskipper]

Originally Posted by goboatingnow

The size of a fuse relates to its housing, the rating refers to its current protection. My suggestion was to standardise on one type of physical size, which removes the needs to carry a huge assortment of differnt sizes. some of which are hard to find.


No mechanical device, which is what a fuse is , can ever "save" electronics, if you look at the failure modes of semiconductor junctions you will see that.


Dave

I have Road cases full of amplifiers and equiment that use fuses as protection for the output transistors on the output loads. As well as for gear that attempts to go dead short only to protected by its fuse.

[goboatingnow]

I have Road cases full of amplifiers and equiment that use fuses as protection for the output transistors on the output loads. As well as for gear that attempts to go dead short only to protected by its fuse.

of for gods sake, Ill say it again, unless the engineer designed the product to survive until a fuse blows, no fuse actually protects electronics, in reality PN junctions fail too fast for a device designed before semiconductors were even invented can actually protect anything. They had some use in valve circuits as valves can resist fault conditions much longer then semiconductor.

Take the good old 2N3055 power transistors, much favoured before the current MOSFET phase. I can destroy that in a short circuit , much faster then any fuse can protect it. Hence I'll design it in to limit the max current, so that in a short the fuse will blow before the device.

Even ultra-fast fuse blow in about 4-100ms, ( depending on size of the current ), again without good design this isnt fast enough.


Try this on your favorite electronics, create a nice short circuit on the PCB, watch what blows up ( hint smoke), check fuse. Is your "electronics protected" no.

If you really want good practice on a boat, then where ever you have a inline fuse, run a dedicated circuit back to a proper rated circuit breaker. I once lost all the helm instruments in a storm, Turned out there was an inline seatalk power supply fuse ( a size and rating we didnt have) inside teh helm binacle, ( that required 12 screws to remove). We never discoved this till two days later or course.

I personally cut them off every thing that has them and supply them via properly rated CB's

That still leaves some , ( Ray are a curse for having then on circuit boards).

Dave

[xymotic]

Originally Posted by Zednotzee

Just remember that with several devices on the same circuit, your fuse will be sized to protect the overall circuit, not the device (ie. 3x 5 amp devices on a 15 or 20 amp fuse). So, a malfunctioning device could still cook itself without blowing the central fuse.


I agree- not too easy to change a fuse on a pitching boat. Have a spare breaker, as they do wear out eventually. I would consider using inline fuses in addition to a central breaker on anything I consider critical, unless it has a dedicated circuit.

The duplex wire is usually used on the AC electrical system. I agree it may be easier to run than seperate wires, but I wouldn't use it for DC wiring simply to avoid confusion. If you're hell bent on using it anyway, it should definitely be labelled, & I would go so far as to label it anywhere it's accessible. Alternatively, you could use safety wire (red/yellow) on your AC circuit.

Your call. I would say circuit number is the most useful information. For longevity, you could try a standard p-touch label with clear heat-shrink over it. This still probably has a finite lifespan outdoors, but should last fine in the cabin.

IMO, the panel should be located away from the companionway & enclosed to reduce water ingress- but have some drainage holes in the bottom, just in case. Use drip loops on the wires. I would also try to keep wiring away from the heat & vibration of the engine compartment.

Non-issue. For any items that draw really big loads (an electric windlass or the like), you'll probably wire a relay anyway, thus isolating the panel from the high-amp circuit.

I would try the interactive "circuit wizard" here- Blue Sea Systems
Free is always worth a shot.

I can't believe nobody has challenged this, because unless I am completely uninformed TRIPLEX is for AC and Red/Yellow safety wire is strictly for DC. Yellow is the new black

[nitpik]

Ditto that:
A yellow wire is DC Neg., so that we do not confuse it with the black AC live wire!

[DeepFrz]

I would keep the inline fuses. They are a good indicator of a problem component. If you had ten items on one circuit and blew the main breaker/fuse you wouldnt know what actually blew.

Only one circuit per fuse, always. The grouping together was meant to mean "group the inline fuses together" I'm sure so that at least you know where they are. Inline fuses spread out all over the boat are for sure a curse. As goboatingnow states, best to have a purpose built fuse panel than inline fuses hidden behind some panel or piece of equipment.

[Heart of Gold]

Its all very con fusing. I will, unfortunately have both breakers and fuses in my boat and in fact have some of this already. I totally agree it would be nice to have a breaker for every device and tried to accomplish this by installing 8 more ccts to the 16 already supplied by the original panel. I have one spare left....and fuses as well. How come you say, because I found that Espar required 3 different rated fuses, has separate fuses in the auto pilot brain, solar panels need to have fusing at the panel, etc. There is nothing wrong with fuses, they actually are faster acting under short circuit situations when sized right than breakers. If a manufacturer requires certain fusing as per directions, you may void any warranty if the protection is too big or not rated for the device and not in the circuit where they want it. Thats my 2 cents Cheers

[goboatingnow]

Originally Posted by Heart of Gold

Its all very con fusing. I will, unfortunately have both breakers and fuses in my boat and in fact have some of this already. I totally agree it would be nice to have a breaker for every device and tried to accomplish this by installing 8 more ccts to the 16 already supplied by the original panel. I have one spare left....and fuses as well. How come you say, because I found that Espar required 3 different rated fuses, has separate fuses in the auto pilot brain, solar panels need to have fusing at the panel, etc. There is nothing wrong with fuses, they actually are faster acting under short circuit situations when sized right than breakers. If a manufacturer requires certain fusing as per directions, you may void any warranty if the protection is too big or not rated for the device and not in the circuit where they want it. Thats my 2 cents Cheers

The bogey man of the warranty, can you substantiate that claim. alternatively you can hunt around your boat for all the hidden fuses in a gale at sea.!

of course there's nothing wrong with fuses per say. its that there are many physical types and many and virtually inaccessible, especially at sea. I still try and remove as many as I can and for those that I cant, I make careful note of where they are and what type they are

Dave

[Heart of Gold]

Nope, not going to even try to substantiate anything and I agree that it would be hard to get at some of the fuses at sea...no denying it. The bogeyman is the manufacturer and if he says that he wants a fuse in a certain place for a piece of equipment that costs in the neighborhood of 2000 or more, i will install the fuse. No question no problem and besides if I install it, I think I will do it in such a way that I will be able to get at it when I need to. cheers,

[Ex-Calif]

One would hope the manufacturer of high end equipment, should he deem equipment protection necessary, will put a circuit breaking device internal to the unit. i.e under the panel that says, "no user serviceable parts inside" or a fuse receptacle near the power pickup. This would hve no bearing on protecting the circuit leading to the device.

You need to be "learned" enough to decide whether the manufacturers recommendation for an exterrnal circuit protection device is to protect the circuit or the unit. That said, for a multi boat buck device I would surely follow the manufacturers installation advice so as not to void a warranty.

[osirissail]

For a beginner I found Nigel Calder's books a very good starting point.
Amazon.com: Boatowner's Mechanical and Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems (9780071432382): Nigel Calder: Books