I'm not an electrician, but I'm not stupid either...

[rgano]

I have experienced two episodes of smoked up boats as a result of burned electrical insulation. It takes a surprisingly small amount of burning insulation to fill the air with acrid white smoke.

The first was on my own boat when my Nextgen 12-volt cooling fan motor seized shorting the unfused wiring an burning up the entire wiring harness of the generator. The new factory fresh wiring harness came with a fuse in the fan wiring. Go figure - installation error. And I understand that Nextgen people did the installations of these units on Mainships built in St Augustine just down the road from their HQA in Jax.

More recently on another boat I was on, a pump motor seized causing another insulation fire. I have no idea who installed this system, but there was a four-slot fuse block at the 12-Volt source in the ER with heavy gauge wiring (8AWG, I think) leading off to three users (Vacuflush, reefer, and unknown), all with 40-Amp fuses.

Yes, I know the fuses are to protect the wiring, but after 20 feet or so of wandering around, the heavy gauge positive lead for the head terminated in a series of ham-fisted tees to accommodate a now-removed macerator pump and an on/off switch for the Vacuflush in the head directly above. The positive and negative wiring for the vacuum generator's pump motor was of a lesser gauge and was the wiring which burned up. It seems to me that the re should have been a fuse at this transition (Vacuflush recommends a 10-Amp fuse). It has been argued to me that since the big wire was properly connected and that if the short run from the power distribution wire was less than 7 inches, ABYC requires no fuse.

Whether that motor wiring was eight or two inches, It seems stupid to me to not fuse as per Vacuflush's recommendation. I am already real tired of smokey boats!

BTW, there was no central 12-Volt breaker panel in this second vessel. Instead, the operator needs to know where the several fuse blocks are located and what there feed.

 

[markbarendt]

It is my understanding that ABYC agrees with you. Any transition to a smaller wire should get a fuse. No exceptions in my book.

 

[sickatea]

I am a master electrician, and I constantly shake my head at the electrical work on my boat. In the real world, bundling is a big no no as the wiring can not breathe and dissipate heat. Low voltage and high voltage cabling MUST be separated for a multitude of reasons. On my mainship, there is a bundle of wiring about 2-3 inches tightly wire tied together with inline fuses buried. FUN times troubleshooting that.

 

[rslifkin]

I am a master electrician, and I constantly shake my head at the electrical work on my boat. In the real world, bundling is a big no no as the wiring can not breathe and dissipate heat. Low voltage and high voltage cabling MUST be separated for a multitude of reasons. On my mainship, there is a bundle of wiring about 2-3 inches tightly wire tied together with inline fuses buried. FUN times troubleshooting that.

Bundling is fine as long as appropriate de-rating is accounted for. In a big enough bundle, the de-rate for wire ampacity is as severe as 40% of original ampacity. The buried fuses is a definite no-no, of course.

 

[rgano]

I am glad to hear that about fusing at any transition.

 

[Marco Flamingo]

Pacific Yacht Specialties has a lot of interesting videos on electrical stuff. The ones on fusing were especially useful to me. Check this out at 4:20.
Check out this video at 4:15. With all that smoke, do you shoot it with a fire extinguisher and redo all your electrical? Best to never have that issue.

I'm glad that sickatea brought up the bundling issue. My PO had put battery cables and smaller wires inside white PVC plumbing pipe as conduit. Makes for a nice presentation, but there are several potential problems. First is plumbing pipe isn't ignition rated for electrical. Second is conduit fill, where the wires heat up but can't dissipate the heat. The NEC has limits on the fill, and I assume so does the ABYC. I can also assume that my PO had no idea about the limits. Also, when the insulation on a cable melts inside the conduit, it can energize the smaller wires with more than they can carry.

But the worst part of bundling just occurred to me having modified, and in some cases removed, old wiring on my boat. I have both AC and DC outlets right next to each other. The wires to those outlets travel in pairs from the electrical cabinet, meaning that hot AC and hot DC are bundled (and have been since 1980). In case of a fault, it would be possible for an AC wire to energize a DC wire. That could be a problem when troubleshooting what appears to be a DC problem.

 

[markbarendt]

I am a master electrician, and I constantly shake my head at the electrical work on my boat. In the real world, bundling is a big no no as the wiring can not breathe and dissipate heat. Low voltage and high voltage cabling MUST be separated for a multitude of reasons. On my mainship, there is a bundle of wiring about 2-3 inches tightly wire tied together with inline fuses buried. FUN times troubleshooting that.

I do understand that head shake!

I'm going through my new-to-me boat as we speak to sort out as much as I can. Spent two weeks in December shaking my head. Amazed I didn't get a concussion for all that motion.

 

[markbarendt]

Pacific Yacht Specialties has a lot of interesting videos on electrical stuff. The ones on fusing were especially useful to me. Check this out at 4:20.
Check out this video at 4:15. With all that smoke, do you shoot it with a fire extinguisher and redo all your electrical? Best to never have that issue.

I'm glad that sickatea brought up the bundling issue. My PO had put battery cables and smaller wires inside white PVC plumbing pipe as conduit. Makes for a nice presentation, but there are several potential problems. First is plumbing pipe isn't ignition rated for electrical. Second is conduit fill, where the wires heat up but can't dissipate the heat. The NEC has limits on the fill, and I assume so does the ABYC. I can also assume that my PO had no idea about the limits. Also, when the insulation on a cable melts inside the conduit, it can energize the smaller wires with more than they can carry.

But the worst part of bundling just occurred to me having modified, and in some cases removed, old wiring on my boat. I have both AC and DC outlets right next to each other. The wires to those outlets travel in pairs from the electrical cabinet, meaning that hot AC and hot DC are bundled (and have been since 1980). In case of a fault, it would be possible for an AC wire to energize a DC wire. That could be a problem when troubleshooting what appears to be a DC problem.

Jeff Cote's videos are great.

 

[sickatea]

I had a go fast boat many years ago before kids and when I would run the boat and use the trim tabs at the same time (one at a time was fine) the fuse for the trim tabs, stereo and lights would blow. I found a schematic for the boat and figured its an easy fix as something is spliced together. I found a huge bundle of wire hidden below the helm that was accessed from the cabin. The wiring looked very similar to this picture! I fixed the problem and sold the boat with rats nest intact.