Re: Distributed vs. Conventional Electrical Systems


Craig Briggs
 

Alan,
That seems an excellent idea. I remember that in 2001 I totally redid SM Miss Lindy's wiring (don't recall the hull number) after it completely burned out for the third time. All the heavy cables in the engine room, from battery to starter to generator to main house feeds had melted solid. As I finished up I still had low volts from the engine to the battery.  Traced it to the starting cables having chaffed about 12 inches down inside the PVC pipe from the battery to the engine (that was supposedly there to prevent chafe). Your solution would have prevented much heartache and expense. 
Will be interested in Bill K's bounce. Perhaps the modern distributed systems do incorporate that.
Craig SN#68


---In amelyachtowners@..., <divanz620@...> wrote :

well said Bill,
BUT that's exactly what we have on our SMs....the anchor windlass, the genoa furler etc have the breakers at the "other end" of the cables that run from the house bank...and...on the standard setup, there are NO FUSES near the battery connections. 
I've put large Blue Sea fuses in the battery compartment on each of my 3 banks of 4 6V series batteries to try to address these issues.
What have you done ?
Cheers
Alan
Elyse SM437

Craig,

I think you (and Amel in the "old days") are simply missing the point of circuit breakers.  They are most certainly NOT there to protect the anchor washdown pump, or the thruster motor, or any other piece of equipment.  There is nothing a circuit breaker can do to "protect" the pump motor, or other device:  If it shorts, it has already died! If, in normal operation, it draws too much current for the wiring to support, then the wiring is undersized.

Circuit breakers are there to protect the WIRING and prevent the catastrophic results that can occur if a short occurs ANYWHERE that overloads the wiring.  This can occur from many faults, none of them likely, but all with disastrous consequences.  Wire chafe is probably the most common cause on boats, but others happen. I'd guess loose connections are a close second.  

Having a breaker at the far end of the wire, away from the battery, completely misses the point of why it is there in the first place. In my opinion, if you have a circuit breaker at the point of use of the power, you might as well just replace it with a switch--it is essentially useless. 

When I ran a service department for a large charter company, one of the annual safety meetings I ran for for my staff was to dead short circuit a 12 volt battery through 14 gauge wire.  Watching solid copper wire burst into flame and literally explode was a sobering experience for people who could easily get into the habit of thinking "its only 12 volts." It really made the point about why fuses and circuit breakers were essential.

There is nothing at all wrong with distributed CONTROL of an electrical system. That is just fancy electronics.  But... you can not "distribute" protection of the wiring. I have never heard a  good reason to run long lengths of un-fused wiring on a boat--or anywhere else.  It is just dangerous--and for absolutely no benefit.  Dangerous overloads rarely occur because of equipment problems.  They occur because of wiring faults.  Do they happen often?  No, not at all. But when they do, it is truly terrifying.  

C-zone, Ocotplex, etc, are NOT wiring protection systems.  They are not "circuit breakers".  They are CONTROL systems.  Very different animals.

I have seen several boat fires at much closer quarters than I ever hope to repeat, and most of them were electrical in origin, all from things that shouldn't have happened--but did.  

Bill Kinney
Sm160, Harmonie
Back Creek, Annapolis, MD




---In amelyachtowners@..., <sangaris@...> wrote :

I'd always thought Amel was ahead of the curve with its Distributed Electrical System. That seems to be the direction the industry is going, now with solid state circuit breakers controlled through the NMEA2000 data network. Eliminates the large industrial style circuit breaker panels of yore and adds great flexibility. Check out CAPI2, C-Zone, Octoplex, etc. Seems Amel is going backwards technologically if they're centralizing. Let's see, your anchor washdown pump shorts and rather than it tripping an adjacent breaker it's got to overload a 15 meter long cable run back to the central circuit breaker panel. To say nothing of the excess wiring to give all equipment a "home run". Must be missing something in this discussion.
Cheers, Craig SN68 Sangaris

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