Electrical, DC Main Circuit Breaker, Part 2: Wiring

The protective cover for the DC main circuit breaker

The wiring of a DC main circuit breaker would seem to be one of the easier tasks in the complete rewiring of a sailboat. After all, there are only two wires that join it. Things, though, in boat work, never are as easy as they seem. There are unexpected problems that create unexpected delays, and before you know it, what seemed at first as if it would require only a hour's worth of work ends up requiring much of the day. Replacing an existing component of an existing electrical system is not difficult. Creating an entirely new system is not. How much wire will I need? Where will I route it? Where will I terminate it? What size terminals do I need? Will this wire obstruct another that I will need to run through the same area tomorrow or the next day? How much chafe protection do I need? Is it the right size for the wire that I need to create for this component? For that matter, is the wire itself the right size for the job? Will it overheat? Have I taken into account the length of the run and the voltage drop? Wait a second, if I move up to a heavier gauge wire, then I'll need to order additional terminals, and maybe additional conduit, and maybe now the other wires that I planned to run through this area won't fit. These and many other similar questions I asked myself time and time again in the planning and execution of this complete rewiring of Oystercatcher my Ericson 25.

In this posting, the second of two in my article on the DC main circuit breaker, I describe the steps I took and the problems I solved to install two simple wires.

Let's start by looking at the protective cover for the DC breaker. You'll notice that there are two wires exiting it. The one on top is labeled "TO DC PANEL." The one on the right, that is fully sheathed, runs to the battery switch.

Now let's look on the other side of the bulkhead where things are nice and pretty. This was the way it looked after I had temporarily installed all of these components.The red switch is the battery switch. To right of it is the battery monitor, and to the right of the battery monitor is the DC breaker.

What I needed to do was to route a wire from the back of the battery switch (the red thing on the right) to the back of the DC breaker (the black thing on the left). It was clear from the start that I would have to route this wire around the back of the battery monitor (the round white thing in the middle). It was also clear that the blue protective cover that I had planned to install over the back of the battery monitor was no longer an option. It had to go.

What was not clear from the start, however, was that the thickness of the bulkhead would prevent me from connecting the wire from the battery switch to the back of the DC breaker.

Having made the wire and labeled it (tasks that I will not here describe, since I have described similar tasks in detail elsewhere in other articles) I now needed to figure out how to remove some of the plywood from the bulkhead in the area around the back of the DC breaker. You'll recall that I installed the DC breaker in the large hole where the old battery switch used to be. I was fortunate to have done this, because the extra space of this old hole gave me a little more working room.

Using my Dremel, with a sanding drum attached, I slowly routed out pathways of sorts for the two wires, being very cautious not to nick any of the wires in the vicinity. This tool can do a lot of damage in short period of time, if you're not careful. I should note that I did all of this work on my knees, while leaning into the cockpit locker.

I also had to be cautious about sanding too deeply. Otherwise, I would create not a rut, but a hole - a hole clean through the bulkhead. Note that I have covered the back of the battery monitor with duct tape to prevent dust from damaging the instrument.

Once I had routed out these pathways to a sufficient depth, I temporarily installed the two wires on the back of the DC breaker. I continue to use the word wire, but since this wire is 6 AWG (American Wire Gauge), it is normally classified as a cable.

At any rate, the wire that I routed upward from the back of the DC breaker led to the DC distribution panels in the galley. To get there, I routed the wire up and over the blue protective cover for the back of the bilge pump switches. Then I routed it through a small opening between the bulkhead and the hull. This wire, sheathed in a black, split-loom conduit, is near the gray plastic conduit on the far left. You just can't see it in this picture. Note that I used the white AC three-wire cable to hold the wire in place.

Below is a picture of the galley. To the left you can see the various white labeled conduits that I have routed through the small opening between the bulkhead and the hull. To right you can see a Blue Sea Systems terminal stud. It was to this stud that I would connect the wire from the DC breaker. The gray, blue, and orange wires are for the DC branch circuits. I address these in separate articles.

Here's the terminal stud after I have connected the 6 AWG wire to it. The other wires, which are 10 AWG, feed the three DC distribution panels. Connecting these three wires to the panels was one of the last things that I did in this complete rewiring of the boat. By this point, the only 10 AWG wire that I had left was yellow, the color I used elsewhere to indicate negative. Not wanting to order another spool of 10 AWG for such a small amount of wire, I decided to use the yellow 10 AWG but to color-code it with red tape and to label it with a + sign to make it clear that it was positive.

Before going any further I needed to seal the joint between the bulkhead and the hull liner in the galley. To do this, I used NP1, a polyurethane adhesive/sealant not unlike 3M 4200 or Sikaflex. NP1 is available in good hardware stores and, since it's sold as a construction material and not a "marine" material, it's much less expensive. It comes in a variety of colors. I selected Off White to match the interior of the boat.

There was a small gap in the joint. I wanted to seal this, so that air would not freely move between the interior of the boat and the cockpit. The NP1 worked well, and the Off White color blended perfectly with the color of the gelcoat on the interior of the boat.

The next issue I faced concerned the final installation of the breaker itself. Up until this point the breaker was only loosely seated in its housing with short screws. Now I needed to mount it with fasteners of sufficient length to prevent it from working itself free. I did not have fasteners of sufficient length, so I had to make a trip to the hardware store. Fortunately, here in Charleston, South Carolina, there are still some traditional hardware stores that sell individual stainless steel fasteners from open bins rather than prepackaged fasteners in quantities that you often do not need.

The fasteners had to be long enough to penetrate the first or second layer of the bulkhead, but not too long that they would pass all the way through these layers.

The DC breaker as it appeared shortly after I had screwed it fully into position.

One problem that I ran into, in terms of the fasteners was that, in the area above the back of the breaker, there was no bulkhead into which I could screw a fastener. The only material that the fastener could grab was the mahogany of the decorative backer. This was not necessarily a problem in and of itself. The problem, rather, was that the end of the fastener penetrated the mahogany and projected into the space where the wire for the DC panel needed to run. To remedy this problem, I pulled out the Dremel and sanded away the end of the fastener. By the time I finished, all that was left was a small stainless steel nub that was barely detectable when touched by a fingertip.

Despite the smoothness and the almost non-existence of this nub, I still thought it would be wise to cover it with several layers of black electrical tape. This was insurance of sorts against the possibility of chafing action.

Next, I needed to focus more closely on the wire that ran from the battery switch to the breaker. Up until this point it was just loosely connected to these two components.

One reason I kept it loose was because I still needed to connect the 1 AWG wires to the back of the battery switch. I had to be sure that this 6 AWG wire would fit with all of these larger wires in this space.

Fortunately, it looked like it would, so I screwed the protective cover into place over the back of the battery switch.

Now I was able to focus on tightening the nuts on the back of the DC breaker and finding a protective cover for it.

Here I encountered another obstacle. When I had earlier hand tightened the lock nuts on these studs on the back of the breaker, everything seemed okay. Now, using a ratchet wrench, I could not get a good grip on these nuts. Therefore, I experimented with different nuts in my miscellaneous bag of stainless steel hardware. A number 10 nut was too small, and a 1/4 inch nut was too large. Puzzled, I made a trip to the hardware store. There, I discovered that the nut I needed was in fact a metric sized nut. Fortunately, this hardware store keeps stainless steel metric fasteners in stock. Back at the boat, I tightened these metric nuts into place using a metric ratchet - a tool that I rarely use, but one that I am glad that I had. I'm still not sure why Blue Sea Systems opted for the metric system on this breaker when they use the English system on all their other components that I have encountered. While I'm at it, I should note that I was able to solve this metric puzzle by taking the original nuts to the hardware store. Yes, this breaker came with nuts. I needed a second set of nuts, because I used the first set as stand-offs. In other words, I installed them behind the lugs. This helped me in the seating of these lugs in this tight space.

Now that I had solved the nut problem, I needed to solve another. As I contemplated how I might protect the back of the DC breaker, I slowly began to remember a conversation that I had had with the tech person at Blue Sea Systems and the notes I had taken at that time. I had asked this tech person if I needed to fuse the wire that would run between the battery switch and the DC breaker. He said that, according to ABYC (American Boat and Yacht Council) standards, the battery switch is a power source. Therefore, he said, if the wire coming off it were to be over 7 inches in length, then it would need to be protected by a fuse. He added, however, that if this wire were to be protected by a sheath or conduit, then it could be up to 40 inches in length without being protected by a fuse. After consulting my notes, I pulled out my tape measure to check the length of the wire. Sure enough, it was an inch or two over the 7 inch limit. I knew that given the space restrictions a fuse was out of the question. Therefore, I decided on the quickest and easiest solution possible - sheathing the wire in a split-loom conduit.

This was something that I really should have done in the first place, given the twists and turns that this wire had to make in such a small space, and given the proximity of this wire to the wire that fed the DC distribution panels. As an added measure of protection I wrapped the end of the conduit many times with black electrical tape to insulate this wire from the adjacent one on the back of the breaker.

In terms of protecting the back of the breaker itself, I experimented with several options until I settled on the one you see pictured below. Yes, this is an electrical box for an AC receptacle. Specifically, it is known as a "shallow work" box, due to its slim profile. It fit perfectly in this space, and it left plenty of room for the two wires to enter and exit the box.

At this point, my complete rewiring of the boat was almost at its end. This is the way the cockpit locker appeared at this time.

Despite the fact that it was obvious to me at this moment that this was the main DC breaker, I still went ahead and labeled the box. This would provide immediate recognition and clarity for me or for anyone else (who might be assisting me) at any point in the future.

Yes, this was a lot of work for two simple wires, but then again I could tell countless stories of similar tasks in the refitting of this boat that seemed at first to be simple, but ended up being much more time consuming than I had ever imagined.

This ends this posting on how I wired the DC main circuit breaker on Oystercatcher, my Ericson 25.

Electrical, ACR (Automatic Charging Relay), Part 1: Installation of Positive Cables

The ACR with its positive cables installed

An ACR, or Automatic Charging Relay, is a useful piece of equipment on a cruising sailboat. It enables you to charge two separate battery banks at the same time from a single charger. Knowing that I wanted to have as much battery power as possible on Oystercatcher, my Ericson 25, I decided that the incorporation of an ACR into my plans for a complete rewiring of the boat was essential. If you've read my article on the DC main circuit, then you'll know that I decided to affix a number of components of the DC main circuit to a backplane - a piece of Starboard, or marine grade HDPE (high-density polyethylene) - and that I fastened this backplane to the bulkhead on the portside of the lazarette, directly beneath some of the other components of the DC main circuit located in the portside cockpit locker. Now I would like to describe how I installed the positive cables to the ACR and how I routed these cables to the fuses and bus bars in the confined space available on this backplane.

Let's begin by looking briefly at the finished job. On the far left is the bus bar for the house battery bank. Between it and the ACR there is an ANL style fuse. The next bus bar is for the reserve battery bank. It too is separated from the ACR by an ANL style fuse. Fuses are essential for protecting the cables. They are, so to speak, the weak link in the chain. Better for the fuses to blow and to break their respective circuits rather than the cables to overheat and to catch fire. I'll say right now that I did not initially plan to use ANL fuses for this job, but instead terminal block fuses. Read on to see why I altered my plans.

The yellow tabs on the Blue Sea Systems brand ACR hold the protective cover in place.

Beneath the cover there are two lugs, both 3/8 inch.

I ordered all my cables from Genuinedealz / BestBoatWire, an online retailer in Brunswick, Georgia. I learned about Genuinedealz from reading the many postings and online articles of Maine Sail, that marine electrician from Maine who does an excellent job explaining the complexities of marine wiring. For a sample of Maine Sail's work, check out the link to his Compass Marine website on the homepage of this site.

Beneath the many pieces of 12 inch heat-shrink tubing were the cables themselves, as well as the lugs that I would use to terminate them.

The cables were manufactured by Almo Wire and Cable in Philadelphia, Pennsylvania. These were not solid copper cables; rather, they consisted of many small strands of tinned copper. Stranded, tinned copper cables are the proper cables for boats, as they are more flexible and more readily resist corrosion. The lugs were manufactured by FTZ Industries in Simpsonville, South Carolina. All the lugs were heavy duty / heavy walled, and they were all tin-plated copper, designed to resist corrosion in the marine environment.

Earlier, I had ordered an FTZ brand heavy duty crimper, product number 94285. As per the advice of Maine Sail, I found that the best deal was at K. L. Jack & Company in Portland, Maine. This crimper was not cheap, but it was worth it. I cannot imagine trying to do this complete rewiring of Oystercatcher without it. Sure you can pay Genuinedealz one dollar in labor to crimp one of these heavy duty lugs on a cable. This would certainly be worth it, if you were replacing a some existing cables whose exact length was known. In my experience from this rewiring, I would have wasted a lot of money, if I had gone this route. There were just too many variables in terms of the twists and turns that almost all of the cables needed to make from start to finish.

At the head of the crimper there are adjustable dies, and on the handles there are charts which indicate which dies you must use for each size and type of lug you are using.

I found the whole FTZ crimper and lug system to be quite easy, as the lugs are color coded and have the proper die settings printed on them. The charts on the handles are good for double-checking, which I always do out of force of habit. It's sort of like that old saying in woodworking - measure twice and cut once.

Before I headed out to the boat, I assembled the necessary equipment.

For this part of the project I got a friend to give me a hand, especially since the crimping appeared as if it would require more than two hands. Here we see my buddy using the cable cutters to score the plastic jacket of the cable. This was 4 AWG cable, in other words, 4 gauge cable according to the AWG (American Wire Gauge) standard.

He cut just enough to allow the lug to fit snugly.

Nice and tight, with no exposed wire, just as Maine Sail suggests on his webpage.

Here's a close up of the adjustable dies for the crimper. To accomplish the crimping, my friend would stand inside the boat at the companionway and I would kneel in the cockpit. He would turn the crimper vertically (in other words, perpendicularly) to the teak you see pictured below. I would then hold the cable in my left hand and the lug in my right, holding the two firmly together while my friend made the crimp. This squeezing action on my part was necessary to prevent the lug from slipping off the end of the cable as the crimp was being made.

The completed crimp. As per the suggestions of Maine Sail, we made the first crimp at the base of the lug (here pictured left), and then we made the second crimp higher up. We also rotated the lug 90 degrees for the second crimp, so as to distribute the sharp edges and rounded edges that are created by the dies. I should note that we took these pictures for illustrative purposes at some point in the overall main circuit rewiring process. That's why this particular cable is not red.

Here we see my friend using the heat gun to make the adhesive lined heat-shrink tubing conform to the lug. This heat-shrink tubing helps to prevent the intrusion of moisture and thus the establishment of corrosion. Note that we've already slid a piece of clear heat-shrink tubing on the cable. This clear heat-shrink will cover the label that we'll soon apply over the red heat-shrink after it cools. Depending upon the size of the heat-shrink, it's often easier to slide the clear piece on in advance of the heating of the colored piece.

It was so much less strenuous doing this work in the cockpit instead of trying to do it in place on the bulkhead in the lazarette. This was the primary reason why I decided to use a backplane for this part of the main circuit.

The first cable that we made was the one that would join the house bank positive bus to the ACR. The Blue Sea Systems ACR allows you to install cables in one of two directions - either vertically, from the bottom, or horizontally, from the side. For this cable, the best approach was from the side. Note the cover in the background. The two slits on the left hand side indicate the "knock-out" portion of the cover. In other words, the consumer, if he chooses to install the cable from the side, can knock-out this plastic tab to allow access for the cable. You really don't have to knock it at all. You just wiggle it back and forth, and it breaks off quite neatly.

Notice that I have taken the time to label this short cable that joins the house positive bus to the ACR. Again, I followed the lead of Maine Sail on this. If you read his many online postings and look at his many outstanding pictures, you'll notice that he is almost obsessive about labeling. Many a person might wonder why it would be worth it to label such a short cable "ACR" when clearly it runs directly to the ACR. Well, I'll tell you why. Because, if you ever have to disassemble your main circuit to replace one item or another, you might have trouble putting it all back together again, if all of your cables are red and all of them are unlabeled. Part of the story of this article I'm presently writing, and which I've not yet discussed, is how I had to alter my original plan and my initial configuration to accommodate ANL fuses. In the process, I had to shift some things around. Having clearly labeled cables made it much easier for me to sort things out.

For all of this labeling I used the Brother brand labeler, Model PT-1290. It cost me about $20 at an office supply store. I was sort of upset at the time I bought it that the AC power cord was not included with it, and that, because of this, I would need to use AAA batteries to power it. I could have bought an AC power cord for $20, but that price seemed outrageous. As it turned out, the labeler was not power hungry, and one set of AAA batteries was sufficient for the entire rewiring project, and beyond.

There is a window on the bottom of the labeler which reveals the specific type of tape cartridge that is in the machine. I used the good stuff - the waterproof TZ tape. This was not the type of tape that came with the machine. I had to order this on my own from an online retailer. Once again, in using this Brother brand labeler and this specific tape, I was following the lead of Maine Sail. Lots of good advice.

Soon after crimping the first lug on this short cable I starting thinking about the terminal fuse block that I planned to install on the stud of the bus bar. The dimensions of this terminal fuse block would affect the length of the cable and thus determine how much I need to remove from the other end of the cable before crimping the second and final lug - the lug that would join this cable to the stud on the ACR.

Below we see the terminal fuse block, part number 5191, sold by Blue Sea Systems. I had read in Maine Sail's many postings and had noticed in his many pictures that he often used terminal fuse blocks to protect the cables that would join his bus bars to the ACR or some other item. Terminal fuse blocks typically are used on battery terminals to provide protection to the battery cables at the power source (rather than farther down the line). Maine Sail, however, as I noticed, also uses them from time to time on bus bars. This, to me, seemed to be a good idea for my set-up, especially given the space limitations I faced on a 25 foot boat.

I had not yet ordered the terminal fuse blocks for this set-up, since it was necessary to spread out my purchases for this complete rewiring of the boat over some period of time. I did, though, figure that I could still accurately determine the length of the cables I needed to make, simply by referring to the excellent specifications provided by Blue Sea Systems on their website. When I consulted these specifications, I discovered, much to my chagrin, that the terminal fuse block would not work at all with the particular bus bar that I had already purchased and installed on the backplane. This bus bar, like the two others, was a common, 150 amp bus bar with four 1/4 inch studs (Blue Sea Systems, part number 2303). The terminal fuse block holder contained a mounting hole that was 3/8 inch in diameter. This meant that if I installed the terminal fuse block on the bus bar there would be a gap of 1/8 between the bus bar stud and the terminal fuse block mounting hole. This meant that there would be poor contact between these two pieces of metal. This meant that this set up would not work. How could I have gotten this so wrong? That's what I wondered. After all, I had seen pictures of Maine Sail using terminal blocks on bus bars, and I knew that, being the stickler he was, he would not permit himself to do sloppy work.

Pausing for some time, I went back and hunted down some of the postings where I had seen him talking about the use of terminal fuse blocks on bus bars. Eventually, I found these postings, and then I discovered my mistake. I had assumed that all Blue Sea System bus bars were the same, in other words, that they all had the same size studs. The bus bars that Maine Sail had shown in his pictures were larger - the 250 amp MaxiBus bars by Blue Sea Systems. In pictures, these look no different to me than the smaller 150 amp common bus bars. Maine Sail did not say that he was using the 250 amp bars, but I could deduce this, because he said that the studs on the bars were 5/16 inch, which is what the 250 amp bars possess. Maine Sail, I should note, did say that despite the 1/16 inch difference between the 5/16 inch studs on the 250 amp bars and the 3/8 inch mounting hole on the terminal fuse block, he found this difference to be tolerable. I should also note that I had originally planned to use 250 amp bars in my set-up, since I figured that this size would be needed for the main circuit, especially since it would be handling the in-rush of amps from the motor whenever I started it. After using the Blue Sea Systems online Circuit Wizard, however, and after consulting with Blue Sea Systems' technical support person, I had determined that the 150 amp common bus bars were appropriate for my set-up.

All of this meant that for this particular set up, I would not be able to use terminal fuse blocks to protect the cables leading from the bus bars to the ACR. This was troubling, at least at first, because space was already very tight on this backplane, and I had not planned on adding anything else to it, except for the many cables that would snake around it.

Eventually, after some thought, I decided that the best thing to do would be to try to fit ANL fuse blocks onto the backplane. I had seen Maine Sail use these in similar situations, so I figured they would be a good alternative, assuming I could fit them into the space.

I began by mounting the one for the reserve bank bus bar horizontally, directly beneath the ACR. The second one I thought I might have to mount on the overhead of the lazarette. That's why I have the cable veering up and away from the house bank bus bar (far left). Throughout this process I had to take into account the other cables that would be joining the bus bars. Across the top of the back plane I would probably run the large, 1 AWG cables that would lead upward to the battery switch in the cockpit locker. Also I would probably run the positive cable for the battery charger across the top.

Mindful of the crowded space on the top side of the backplane, I eventually began to think that I should route the cable for the house bank bus bar downward (and then upward) to the ACR. I could not make any final decisions, however, until I did some more work in the boat.

With the backplane back in the lazarette, I began to make and install some of these other cables. I had already run the AC cables (gray conduit) and the AC grounding cable (black conduit) downward from the cockpit locker. These didn't appear as if they would present any problems.

Next, I ran the 1 AWG battery switch cables downward from the cockpit locker. These were the things I really needed to take into consideration.

In the picture below, you see the battery switch cables coming down. You also see the positive and negative cables for the battery charger coming in from the right hand side of the picture.

After holding up all of these cables with my hand, trying to get a sense of how they could all fit into this space, I eventually decided that the best location for the ANL fuse block for the house bank bus bar was between that bus bar and the reserve bank bus bar.

This allowed me to route the cable, or I should say cables, to the ACR in the most space-saving way possible. Note that in the picture below I have placed a cable on the top side of the backplane as a mock-up, just to make sure that I was allowing enough room for everything.

Later, after I had begun to install more of the other cables for the main circuit, I saw that my decisions regarding the location of the ACR and the routing of the cables to it through the ANL fuses had been a good one. Everything was starting to fit together well.

This ends this posting on how I installed the positive cables for the ACR in Oystercatcher, my Ericson 25. In the next posting in this series, I discuss my installation both of the LED indicator light and of the grounding wire for the Automatic Charging Relay.