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  #26   IP: 107.0.6.150
Old 07-06-2016, 11:02 AM
hanleyclifford hanleyclifford is offline
 
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Quote:
Originally Posted by ndutton View Post
A properly engineered circuit tolerates all connected loads regardless of their sum with no more than a 3% voltage drop. If you're experiencing more than 3% you need to re-read and understand the many posts on this forum describing voltage drop in detail, then rewire the substandard circuit according to established protocol. Alternatively, if you're unwilling to wire the circuit properly you can certainly add more and more circuits. A properly sized single circuit is far less complicated than several circuits with several oil pressure switches and much easier to troubleshoot due to its simplicity.

Remember, 3% max voltage drop. Anything more is indeed sloppy, poor and substandard engineering/installation.

Sure it is and the fuse is doing exactly what it's supposed to do. Moyer Marine has sized the fuse in their kit @5 amps for good reason. The best any of us can do is follow the instructions included in the kit.
The 3% voltage drop mantra is arbitrary and violated everywhere with impunity. Read the source of it and you'll see why. Sizing of fuses should be based on actual load, not a recommendation, and we have seen what can come of studious attention to manufacturer's propaganda. (remember Pertronix?)
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  #27   IP: 76.179.157.47
Old 07-06-2016, 12:57 PM
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BunnyPlanet169 BunnyPlanet169 is offline
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Quote:
Originally Posted by hanleyclifford View Post
The 3% voltage drop mantra is arbitrary and violated everywhere with impunity. Read the source of it and you'll see why. Sizing of fuses should be based on actual load, not a recommendation, and we have seen what can come of studious attention to manufacturer's propaganda. (remember Pertronix?)
Hanley - I really don't understand where you're going here. Are you dissing the NEC and ABYC? These are well intentioned, and well supported fire safety codes.

3% is an excellent design goal, and inherent in that calculation is the circuit design current, ampacity of the wire, the temperature of the space, and ultimately the fuse requirements.

Numbers greater than 3% will work, no doubt for a while, but the risk is a runaway thermal reaction - as voltage drops, the current goes up, heating the wire, which increases it's resistance, which further drops the voltage, which increases current, which eventually burns the insulation and shorts.

I've burnt up extension cords doing just this.

I don't know why you'd want to recommend ignoring this.
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  #28   IP: 107.0.6.150
Old 07-06-2016, 05:28 PM
hanleyclifford hanleyclifford is offline
 
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Quote:
Originally Posted by BunnyPlanet169 View Post
Hanley - I really don't understand where you're going here. Are you dissing the NEC and ABYC? These are well intentioned, and well supported fire safety codes.

3% is an excellent design goal, and inherent in that calculation is the circuit design current, ampacity of the wire, the temperature of the space, and ultimately the fuse requirements.

Numbers greater than 3% will work, no doubt for a while, but the risk is a runaway thermal reaction - as voltage drops, the current goes up, heating the wire, which increases it's resistance, which further drops the voltage, which increases current, which eventually burns the insulation and shorts.

I've burnt up extension cords doing just this.

I don't know why you'd want to recommend ignoring this.
I do not recommend ignoring anything useful. However, of far greater importance than arbitrary goals is the design and propagation of an electrical system, "tree" if you will. The only good voltage drop is the intentional one, and we have seen here a number of unintentional voltage drops that had useful results. I follow the rule that no wire should be larger than the wire that feeds it. You would be surprised at how many violations of this occur. Similarly, no wire should feed more than one wire equal to itself, or any combination greater than itself. This is one reason why coil + should remain as clean as possible. There is a lot more to building a clean, safe and effective system than rigid adherence to arbitrary numbers. If voltage drop is a big priority (as it should be), here is a practical suggestion: start the system with the largest wire practicable for present and any future considerations. For me that means #2 cable coming off the batteries, both red and black, and ganging them up to a big buss bar before distribution.....maybe we should start a thread on DC system construction?

Last edited by hanleyclifford; 07-06-2016 at 05:37 PM.
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  #29   IP: 24.152.132.65
Old 07-06-2016, 06:51 PM
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Wow Hanley, just Wow.

Jeff, I admire you for trying to offer reason but you'll find the other side of the argument is belief based rather than proven physics and electrical engineering/design as set forth by the ABYC, NFPA and NEC and is not interested in anything those safety agencies have to say. Previously the belief based side has even advocated the ABYC is outdated and should be rewritten to align with the beliefs (don't hold yer breath waiting for that to happen).

Anyway, thanks for trying.
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  #30   IP: 73.97.153.165
Old 08-26-2016, 08:30 PM
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I ran the motor fro many hours on a recent trip and the motor never stopped and ran very reliably.
Changing the pump with the moyer's kit and changing the fuel hoses was the right thing to do.
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