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Old 27-03-2011, 12:34   #1
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Electrical Redesign Advice

I am planning a rewire my Pearson 323 (1981), and of course, I am adding many new loads, as well as an NMEA2000 network. I have made a list of present loads and new loads, and am currently estimating the power draw and max current for each load (not done yet). I will probably add a new starting battery in addition to the two 105 AH batteries I currently have...and depending on my final load summary, may add another house battery.

However, in this planning, I have some basic questions about design and implementation. Allow me to fish for a few comments:

1. Where can I find literature regarding design philosophy for (a) what loads to group on what circuits, (b) partitioning of main bus bars versus supplemental bus bars (location, when to do it versus not, etc), (c) same question regarding main panels versus supplemental panels? I should point out that I am aware of ABYC standards (but I need to study them), and I understand how to size wire based on ampacity, voltage drop, and the concept of derating wire for high temp environment (e.g. in engine rooms).

2. Many instruments have in-line fuses to protect the instrument. Is it common practice (i.e. better) to wire to an accessible central fuse panel, instead of using the individual in-line fuses? Also, should every instrument, stereo, etc., get a fuse? Can the fuse be located several feet from the load?

3. For main circuits, I assume circuit breakers are better than fuses, right? Is there any situation where I might consider a breaker and a fuse (in series)?

4. I assume if there are redundant instruments (I have a few), they should be on separate circuits, in case one circuit fails. Agree? Is there a philosophy on redundancy I could read?

5. Is it better to run wiring pairs (or multiconductor) than individual wires? For example, I can buy spools of 2-conductor, 3-conductor, 4-conductor (etc) wire that has a white sheathing. I think this would be a more convenient way to organize wires than running individual conductors (but perhaps at higher cost). But, with sheathed wire, I assume you cannot color code (only red/black), as you can with individual wires. My idea there is to label each sheathed wire along the length, and at the terminations. Comment?

6. Regarding labeling, is there a "standard" method I could use? For example, circult number, termination number, conductor size, any other info to include in the code? Is there a recommended label making device? What about a label tape type that is bullet-proof to years of marine exposure?

7. Should the DC main panel be enclosed at the back, to exclude water in the event of a dousing (say, if the cockpit is pooped). On my Pearson, the panel is currently on the back wall, near the galley, and is open to the cockpit locker area, and in event of a major dousing, could see some water.

8. If the main panel is enclosed, is there an issue with heat buildup behind the panel? Any comment on how to ventilate for cooling (if needed)? My idea is to build a wall/box that is water resistant to protect the panel, then construct the panel so that it drops forward inside the galley area for access to the wiring terminations. Wires will pass through tight fitting grommets that exclude most water from the box. I wasn't planning on any ventilation holes.

9. Are there any AutoCAD or MS Visio wiring library symbols I might consider purchasing for my design effort?

Thanks for helping me get started.
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Old 27-03-2011, 12:56   #2
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Re: Electrical Redesign Advice

Best thing I can say is something I learned from a guy who used to work on submarines. Keep it simple and accessible. Try and keep your draw down as much as possible (heavier gauge wire ann shorter distances), put some thought into planning the location of any electronics, think about LED lighting (below decks as well as nav lights)
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Old 27-03-2011, 13:52   #3
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Re: Electrical Redesign Advice

Quote:
Originally Posted by StringBimini View Post

2. Many instruments have in-line fuses to protect the instrument. Is it common practice (i.e. better) to wire to an accessible central fuse panel, instead of using the individual in-line fuses? Also, should every instrument, stereo, etc., get a fuse? Can the fuse be located several feet from the load?
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.
Quote:
3. For main circuits, I assume circuit breakers are better than fuses, right? Is there any situation where I might consider a breaker and a fuse (in series)?
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.
Quote:
5. Is it better to run wiring pairs (or multiconductor) than individual wires? For example, I can buy spools of 2-conductor, 3-conductor, 4-conductor (etc) wire that has a white sheathing. I think this would be a more convenient way to organize wires than running individual conductors (but perhaps at higher cost). But, with sheathed wire, I assume you cannot color code (only red/black), as you can with individual wires. My idea there is to label each sheathed wire along the length, and at the terminations. Comment?
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.
Quote:
6. Regarding labeling, is there a "standard" method I could use? For example, circult number, termination number, conductor size, any other info to include in the code? Is there a recommended label making device? What about a label tape type that is bullet-proof to years of marine exposure?
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.
Quote:
7. Should the DC main panel be enclosed at the back, to exclude water in the event of a dousing (say, if the cockpit is pooped). On my Pearson, the panel is currently on the back wall, near the galley, and is open to the cockpit locker area, and in event of a major dousing, could see some water.
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.
Quote:
8. If the main panel is enclosed, is there an issue with heat buildup behind the panel? Any comment on how to ventilate for cooling (if needed)? My idea is to build a wall/box that is water resistant to protect the panel, then construct the panel so that it drops forward inside the galley area for access to the wiring terminations. Wires will pass through tight fitting grommets that exclude most water from the box. I wasn't planning on any ventilation holes.
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.
Quote:
9. Are there any AutoCAD or MS Visio wiring library symbols I might consider purchasing for my design effort?
I would try the interactive "circuit wizard" here- Blue Sea Systems
Free is always worth a shot.
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Old 27-03-2011, 13:58   #4
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Re: Electrical Redesign Advice

Hi, I am a land based electrician and am in the process of learning the fine art of wiring boats, namely my own. Where I am learning a lot of what you are asking is from a guy that goes by Mainesail over on the Sailboat Owners site under expert forums. You might want to talk to him.
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Old 27-03-2011, 14:11   #5
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Re: Electrical Redesign Advice

Mainesail is very knowledgeable.
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Old 27-03-2011, 14:21   #6
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Re: Electrical Redesign Advice

What gets me is the "land based electricians" who understand AC but can't figure out DC...I never did get AC right...//DC just seems to be alot more direct...hmm, isn't that what D stands for.
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Old 27-03-2011, 14:40   #7
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Re: Electrical Redesign Advice

Quote:
Originally Posted by wolfenzee View Post
What gets me is the "land based electricians" who understand AC but can't figure out DC...I never did get AC right...//DC just seems to be alot more direct...hmm, isn't that what D stands for.
Oh, its not the theory I need to brush up on, I deal with very complicated DC controls everyday. It is more the marine code and use of the specialized wire, dealing with batteries, solar panels, proper tools, etc, etc. that I need to understand and Maine Sail fills in a lot of the blanks. DC circuitry was basic first year trade school. Don't worry, I can and have found many problems on my boat, and others but want to be sure and fix them properly using the right tools, the right wire and components so reliability is attained.
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Old 27-03-2011, 14:54   #8
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Re: Electrical Redesign Advice

My knowledge of electricity as well as the complexity of electrical stuff on my boat is alot simpler than some people put into thier boats, the only thing added in the last 40 years was bildge pump (auto and manual) and an external plug for the cockpit. The only thing added was a switch panel with breakers all 10 of them (2 are blank).
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Old 27-03-2011, 15:11   #9
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Re: Electrical Redesign Advice

Quote:
Originally Posted by Heart of Gold View Post
Oh, its not the theory I need to brush up on... It is more the marine code and use of the specialized wire, dealing with batteries, solar panels, proper tools, etc, etc. that I need to understand and Maine Sail fills in a lot of the blanks.
Don't worry if people start spouting off about ABYC as if it's some kind of religious document- the ABYC is purely voluntary, & many boat manufacturers don't fully comply with it.

If you follow most electrical practices, the only place you can really get into trouble is with grounding & bonding. This is one case where you don't want to tie everything together.
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Old 27-03-2011, 15:30   #10
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Quote:
Originally Posted by StringBimini
1. Where can I find literature regarding design philosophy for (a) what loads to group on what circuits, (b) partitioning of main bus bars versus supplemental bus bars (location, when to do it versus not, etc), (c) same question regarding main panels versus supplemental panels? I should point out that I am aware of ABYC standards (but I need to study them), and I understand how to size wire based on ampacity, voltage drop, and the concept of derating wire for high temp environment (e.g. in engine rooms).
Abyc, European RCD standards available from ISO. Caldera book.

Quote:

2. Many instruments have in-line fuses to protect the instrument. Is it common practice (i.e. better) to wire to an accessible central fuse panel, instead of using the individual in-line fuses? Also, should every instrument, stereo, etc., get a fuse? Can the fuse be located several feet from the load?
Inline fuses IMHO should be banned. If you must have fuses group them in a panel. Preferable to put each item on a resettable breaker though that can lead to lots of breakers and wire.

Quote:
3. For main circuits, I assume circuit breakers are better than fuses, right? Is there any situation where I might consider a breaker and a fuse (in series)?
Yes sometimes where you tee lots of different size loads of one breaker. Try and avoid that. CBs are always better then fuses.

Quote:

4. I assume if there are redundant instruments (I have a few), they should be on separate circuits, in case one circuit fails. Agree? Is there a philosophy on redundancy I could read?
yes good idea

Quote:

5. Is it better to run wiring pairs (or multiconductor) than individual wires? For example, I can buy spools of 2-conductor, 3-conductor, 4-conductor (etc) wire that has a white sheathing. I think this would be a more convenient way to organize wires than running individual conductors (but perhaps at higher cost). But, with sheathed wire, I assume you cannot color code (only red/black), as you can with individual wires. My idea there is to label each sheathed wire along the length, and at the terminations. Comment?
2core dc cable is often used for common low current devices, cabin lights , bilge pumps etc. Single cores tend to be used for heavier current. Label as frequent as you can bear.

Quote:
6. Regarding labeling, is there a "standard" method I could use? For example, circult number, termination number, conductor size, any other info to include in the code? Is there a recommended label making device? What about a label tape type that is bullet-proof to years of marine exposure?
Make a circuit diagram and assign connector termination numbers.

Several cable marking machines exist see google some are expensive. If it's a big job it's a worthwhile investment

Quote:
7. Should the DC main panel be enclosed at the back, to exclude water in the event of a dousing (say, if the cockpit is pooped). On my Pearson, the panel is currently on the back wall, near the galley, and is open to the cockpit locker area, and in event of a major dousing, could see some water.
Good idea follows industrial practice. Use standard glands.
Quote:
8. If the main panel is enclosed, is there an issue with heat buildup behind the panel? Any comment on how to ventilate for cooling (if needed)? My idea is to build a wall/box that is water resistant to protect the panel, then construct the panel so that it drops forward inside the galley area for access to the wiring terminations. Wires will pass through tight fitting grommets that exclude most water from the box. I wasn't planning on any ventilation holes.
Unless you put active heat generators inside the cabinet ( electronics etc). Then no need for ventilation.

As to cAD design aids there are many see google

Dave
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Old 27-03-2011, 15:45   #11
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Re: Electrical Redesign Advice

Quote:
Originally Posted by Zednotzee View Post
Don't worry if people start spouting off about ABYC as if it's some kind of religious document- the ABYC is purely voluntary, & many boat manufacturers don't fully comply with it.

If you follow most electrical practices, the only place you can really get into trouble is with grounding & bonding. This is one case where you don't want to tie everything together.
Yep, this is probably the most important component of any electrical system on a boat as if there is no isolation between shore power ground and system negative, in a saltwater environment you can start losing zincs and expensive boat parts really fast. As far as the code goes, if more owners and manufacturers followed it closer there would be a lot less problems by and large.
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Old 27-03-2011, 15:48   #12
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Re: Electrical Redesign Advice

Although I live in Canada, our codes are similar Here is a link you may find useful http://www.abycinc.org/committees/e-11.pdf
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Old 27-03-2011, 17:09   #13
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Re: Electrical Redesign Advice

Heart_Gold, thanks for the link. I will read it cover to cover. You aren't related to Neil Young are you?
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Old 27-03-2011, 17:13   #14
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Re: Electrical Redesign Advice

Also thanks everyone for the other references. I will look up Mainesail, and the Blue Sea "free" design software.
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Old 27-03-2011, 19:47   #15
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Re: Electrical Redesign Advice

Stick as close as you can with the ABYC codes and use only Marine rated wire and connectors. Remember that SAE and AWG wires are not the same size.
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