....well said Norm!!!
----- Original Message -----
From: Norm of Bandersnatch
To: [email protected]
Sent: Tuesday, July 22, 2008 5:08 PM
Subject: Re: [Liveaboard] 12 VDC buss
Mike,
Re-read my message(s).
Look for the part that says: "Each load has it own fuse or breaker at its
feed point. So a short in a load would only pop its fuse."
In my previous message:
"...Attach the offsticker to the block and then attach the loads to the block
through in-line fuses to protect the feedlines.
Another termination for light to medium loads is a nice black plastic
terminal block I found at NAPA auto parts stores. It has slots for eight
blade-style automotive fuses, and a 1/4" spade lug for each load wire. There
is a stud for the positive wire to feed the fuses."
A short is simply the maximum overcurrent. A fuse or breaker is to prevent a
fire caused by overcurrent (including a short) that would heat electrical
devices up to the point of fire.
Bear in mind that things can be heated up to the point of fire without an
overcurrent condition happening, and therefore not stoppable by means of a fuse
or breaker. In houses ashore aluminum wire on non-compatible terminals have
corroded to the point that they heat up at normal loads and sometimes heat up
to the point of starting a dwelling fire and even killing the occupants. So a
fuse or breaker is not the end-all of preventing electrical fires.
Norm
S/V Bandersnatch
Lying Julington Creek
30 07.695N 081 38.484W
----- Original Message -----
From: mg
To: [email protected]
Sent: 7/22/2008 4:47:14 PM
Subject: Re: [Liveaboard] 12 VDC buss
So you are saying you have this huge 00 fuse capable of hundreds of amps,
protecting all your instruments and 12V devices that only take at most 5 or 10
amps? Wow.
It is ovecurrent protection, not short protection.
Mike
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From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Norm of
Bandersnatch
Sent: Tuesday, July 22, 2008 1:28 PM
To: [email protected]
Subject: Re: [Liveaboard] 12 VDC buss
Good point Lee.
I do have a circuit breaker at the feed point of the buss. It is a
three-phase ac surface mount breaker I found cheap at a flea market, of 100
amps each leg, each leg wired in parallel. It is also handy for turning off
the buss when I am working on it. The only time it trips is when I have an
extraordinary load on the windlass, but I can bypass the breaker if I need to
do so. And, yes, I did consult with the breaker manufacturer, Heinemann, who
said the breaker would work fine in my application except for possible
premature tripping due to uneven distribution of the load across the three legs.
But I would not hook up any 12 VDC system in a boat without a way to shut
it off. Electrical fires are a large threat and you must be able to shut off
the juice to have a prayer of putting out the fire.
The only exception is the engine starting circuits. I have never seen a
breaker or fuse on a starting circuit, not that there are none anywhere. I
think Ann-Marie explained it well some time ago why that is so but I don't
remember his words, but I imagine the same reasons would apply to the buss.
In order to have a significant effect on the buss the short would have to
be very large to survive. That is, whatever is causing the short would have to
be pretty big to survive being across the buss as the buss can deliver hundreds
of amps which would turn most shorts into opens in short order. Even more so
if I didn't have the 300 amp breaker, over a thousand amps would be available
to open the short.
Each load has it own fuse or breaker at its feed point. So a short in a
load would only pop its fuse.
Also note that most of the buss is very well protected being tucked up
against the hull out of harms way.
I am not at all worried about something shorting the buss.
Also note that the 12 VDC buss system is the latest, greatest, thing on
the new boat market championed by such luminaries as Nigel Calder.
Norm
S/V Bandersnatch
Lying Julington Creek
30 07.695N 081 38.484W
----- Original Message -----
From: Lee
To: [email protected]
Sent: 7/22/2008 1:17:49 PM
Subject: Re: [Liveaboard] Hello everyone
Hi Norm,
I see all of praise of your electrical setup. But I frankly am
scared to death of it. Do you have any circuit breaker protection in the event
of a dead short. From what you have listed in your setup a dead short would
affect every electrical component connected to the two feeds on each side of
the boat. It could also short out everything connected to it (if you had a
problem, everything would be dead). I totally understand the concept of your
setup but the risk could totally fry everything on your boat not to mention the
fire hazard of the setup. Am I missing something here? This is not an attack
of your setup but rather some clarification of it.
thanks
~ ~~ ~ _/) ~~~ $ -Lee
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Norm of
Bandersnatch
Sent: Tuesday, July 22, 2008 9:14 AM
To: [email protected]
Subject: Re: [Liveaboard] Hello everyone
Welcome to the List Randy,
Hard to give advice to an experienced cruiser. Fifty-five feet LOA (I
assume on deck, not including bowsprit - part of the rigging) is a big boat.
My 63' on deck vessel can be a handful, especially the maintenance.
I do have a "bullet proof" fuel system that has evolved to be so over
the course of the decades I have been building my vessel. If you like I will
send a write-up about it.
My 12 VDC system consists of large gauge (00) twisted pairs from the
house batteries to the bow and to the stern along the hull/deck joins on both
sides of the hull that feed all the 12 VDC loads from off-stickers very near
the load itself. They come together at the bow to feed the windlass. All the
loads act as if they are connected directly to the battery. It is Good Thing
when every device is receiving essentially house battery voltage no matter
what. other loads are on. This is similar to the latest whiz bang system with
electronic switches to turn loads on and off but without the fussy, expensive,
unreliable, electronics.
You don't have to have the load switches at a central control panel
with a pair of conductors for everything. With the big buss system the
switches are at the loads. You gain a little exercise, and a huge degree of
reliability, ease of maintenance and functionality.
Cell phones, ATMs and our Verizon Air card for Internet access. Most
lights are fluorescent, more LEDs as time goes by. Propane cooking and hot
water.
If you have any specific questions just ask. I have been living aboard
since launching in 1981, cruising and anchoring out (no marinas) since 1997.
Norm
S/V Bandersnatch
Lying Julington Creek
30 07.695N 081 38.484W
----- Original Message -----
From: Randall Gibbons
To: [email protected]
Sent: 7/21/2008 2:53:29 AM
Subject: [Liveaboard] Hello everyone
I am new to this list and just wanted to say hello. I am once again
in the market for a liveaboard boat, and once again pursuing the only lifestyle
that have ever really made me happy. I have lived aboard twice before on a
couple of different boats, but life changes, divorce, and now realizing that my
yearning for adventure is the only thing that keeps me motivated, has led me to
this place of realization that I can't settle down. My last boat was a 55 LOA
Gloucester Schooner replica and I made the mistake of letting it go to try and
please my wife at the time, only to end up in a divorce 3 months
later-------with no boat.
Anyway, I have started the search for my new home and I am feeling
the excitement began to come alive again. I look forward to hearing from you
all.
Randy
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