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Old 11-10-2010, 20:05   #31
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Same thing here UM

"I have personally seen expensive breakers operating in clean conditions that would not trip at a current even close to the rated capacity. Plus or Minus 25% is a typical operating range of a used breaker. I am not saying that I would not have breakers on my boat because I do have and use them. I am saying that they are not yet the simple cure-all that you make them out to be."

I agree whole heartedly. A different voltage situation but the theory is the same. I had a building 460/277vac supply voltage. The lighting was all 277vac

FUSED disconnect was in front of the 460/277 vac transformer that fed three floors, each with a 277vac BREAKER panel which fed the lighting circuits.

WHENEVER there was a fault in any lighting circuit no BREAKER ever tripped, ever, out of 27 stories. When we got a call that 1/3 of the lights were out on 3 floors, we grabbed a fuse. We joked that you could weld with this breaker manufacturers breakers before they'd trip.

I'll use fuses thanks, except on loads I expect tripping, motor loads such a windlass, motorized winch.

My two cents

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Old 11-10-2010, 20:12   #32
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A new Solar Panel installation

I have 2 - 210 watt solar panels that I'm installing on top of the new hardtop over the center cockpit. They are individually rated at 11.52 amps @12V and will be connected to an Xantrex C-40 controller that can handle 12/24/48 volts, then to a 880AmpHr battery bank.

Should I connect them in series or parallel. Please help.

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Old 11-10-2010, 20:18   #33
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Originally Posted by senormechanico View Post
To get around all that voltage drop, I guess the only course of action is to hold off on all cruising until physics and progress gives us superconductors for the entire boat's electrical system.
Beer. That's what I use to avoid worry about all things electrical.
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Old 11-10-2010, 23:29   #34
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A new Solar Panel installation

I should have posted these specifics on the solar panels:

Power (W) 210 Watts
Open Circuit Voltage (V) 23.10 Voc
Short Circuit Current (A) 12.20 Isc
Maximum Power Voltage (V) 18.70 Vmp
Maximum Power Current (A) 11.23 Imp

Now I think I'll connect them in parallel but I wonder if I've selected the right PWM charge controller or if another type would be better.

Jim
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Old 12-10-2010, 08:44   #35
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Err - Um Saudale, I was confining myself to DC circuit breakers as the OP was taking about DC. We can have a lively debate about RCD's if you wish, But most of what you write as applied to magnetic or thermal breakers for dc is nonsense. Fuses are used because they are cheap, end of story. No electronic device properly designed needs them, especially not for reverse polarity, ( which can be protected by a mere diode).

Hence is E-T-A description
"All models within the 8340 and 8345 range offer a choice of fast acting magnetic operation or hydraulically delayed switching characteristics which may be selected to suit a range of application requirements such as those of the telecommunications and process control industries, where precise and dependable protection of sophisticated systems cannot be compromised. "

Hardly protecting a "wire",,equally printed circuit board versions a available. The fact is a CB replaces a fuse in any circumstances except cost.

Dave
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Old 12-10-2010, 09:05   #36
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Originally Posted by boatrips View Post
I should have posted these specifics on the solar panels:

Power (W) 210 Watts
Open Circuit Voltage (V) 23.10 Voc
Short Circuit Current (A) 12.20 Isc
Maximum Power Voltage (V) 18.70 Vmp
Maximum Power Current (A) 11.23 Imp

Now I think I'll connect them in parallel but I wonder if I've selected the right PWM charge controller or if another type would be better.

Jim

Jim,

The Parallel vs Series debate is even more "polarizing" (sorry) than Fuse vs Breaker and I don't dare comment.

The best guideline I have seen for sizing controllers is to multiply the combined short circuit currents for your panels by 1.5. Yours would be 12.2 * 2 * 1.5 = 36.6 so your Xantrex C40 should be just right.

Mike
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Old 13-10-2010, 08:27   #37
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Dave:

Thanks for the input. We are all entitled to an opinion.

The typical circuit breaker installed on pleasure boats is a magnetic type AC/DC with no choice of any operational characteristics other than a current operational "range’ and I say range because they are notoriously undependable.

We have not even touched on time delay characteristics of which you have absolutely no choice over in all but the must expensive of breakers and those are not typically available to the average boater or even the average boat electrician.

As to the reverse polarity, yes a diode will block reverse current and that is all it will do. So the typical owner/installer then takes the device back to the dealer and tell him it does not work. With the blown fuse scenario, there is a head slapping ‘Duh!" and the wires reversed.

I am not sure as to why your views are so adamant. The prudent man does not dismiss so readily as you and thus I suspect there are issues here beyond fuses and wires. None-the-less….

I will continue to have my beliefs and you are entitled to yours. I suspect that even with our differences either one of us would do good conscientious work. I just would prefer that you did your work on your boat and I am sure you would prefer me to keep my methods to myself also.

Um Saudade
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Old 13-10-2010, 08:59   #38
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I'm not sure GB. Are you saying that all that is needed is a circuit breaker at the panel? Or are you saying install a circuit breaker at the device as well? If all you provide for protection is a circuit breaker at the panel at the begining of the run and elimintae the fuses at the device I assure you that you are asking for trouble. Considering the usual 12V boat, wire runs can be long. Wires size as you know are larger depndant on length of run. If you run a #8 wire to a device and protect it at the begining of the run and eliminate protection at the device then any wires smaller than the #8 will become your fuse in the case of a short, burning through. Many devices themselves are wired the 14-24AWG range. Running a 15-20 amp breaker protected #8 as an example to these devices is a fire waiting to happen within the device if things go wrong.
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Old 13-10-2010, 09:33   #39
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Where to put the circuit protection device is system dependent. Presumably the biggest danger is a group of sunny panels overpowering a parallel connected shaded panel. In that case the protection device should be at the parallel junction point - not at the solar panel. A good protection diode may be all that is needed as they are quite reliable. In series with the diode would be a good place to put a permanent fuse (that will never open or need replacement but will meet the safety requirements).

The output current of a panel is absolutely limited to it's maximum current (Imp) and proper wire selection is all that is required for safety.
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Old 13-10-2010, 09:39   #40
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PS I wonder what grief I will cop for this? I DON'T use Paper charts either! [/QUOTE]

wait till you get hit by lighting or a big power surge that fries your electronics,,,,,, you will wish you had a paper chart and a good old magnetic compass,,,,,which way is north?????
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Old 13-10-2010, 09:42   #41
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...which way is north?
Left of the rising sun
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Old 13-10-2010, 09:50   #42
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Left of the rising sun

only in lower and mid latitudes,,,,, no left of the rising sun in the higher latitudes,, but who need paper chart anyways with the re-lability of the windows operation system and chinese electronics
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Old 13-10-2010, 09:55   #43
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I thought this thread was about fuses?

The other bizo has dripped into inanity somewhere else.


Mark

PS did I just make up a new word?
PPS a curicuit breaker costs $58 and a fues holder and fuse $4.
PPPS I am only here because I am 'watching' the live text of the Chilean miners rescue. 'Live text' is about as boring as this thread!
PPPPS The computer has just Beeped. The Electronic chart has told me the wind has changed. Your fish wrapping couldn't do that, eh?!
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Old 13-10-2010, 10:11   #44
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The other bizo has dripped into inanity somewhere else.


I thought it was BOZO not bizo

we could liven this thread up a bit if you like,,,,

how is the beneteau or is it a bendatoe
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Old 13-10-2010, 12:14   #45
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If you run a #8 wire to a device and protect it at the begining of the run and eliminate protection at the device then any wires smaller than the #8 will become your fuse in the case of a short, burning through.
I am always a fan that the complete circuit shoudl withstand the breaker current, Part of the problem being that too many boat manufacturers dont fit enough breakers, too many parallel loads, breakers rated too high.

My old "quality" british boat had 50 DC breakers ( inc 8 spare) and 20 AC breakers, most system on one breaker per load. No inline fuses anywhere, all circuit wiring capable of takingb the breaker load

The otherthing Telie, is that even a small gauge wire will handle a quite large current for the time it takes to trip.

Dave
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