Wiring the aft cabin

[guyrj33]

Originally Posted by ashmun

Please keep in the back of your mind that DC wiring is the #1 cause of boat fires and that percentage has been increasing over the last decade. Over Current Protection (OCP) is not so much a problem with LED lighting but it is with most everything else (bilges, blowers, etc.). Nigel Calder’s book, Boatowner’s Mechanical and Electrical Manual (latest edition) has a really good section on wiring and OCP. Also try to stick to marine grade wiring and fuses plus there are plenty of really good wire sizing apps out there on the smart phone and web, just make sure it’s a marine DC wiring app based on ABYC, ISO, or AUS/NZ like BlueSea’s Wizard, DC Wire Sizer, Wire Sizer, etc.. I received a video this month showing a 2/0 cable getting hot because of a ‘off-brand’ ANL fuse. The cable was fine once the fuse was replaced with brand name (in this case, BlueSea). Safe Sailing.

How did one fuse and not the other cause the wire to get hot?

[Americanrancher]

Originally Posted by steamgoat

Don’t want to be rude,but a connector strip ,in my view would be a ‘cob job’.
Put in a small fuse box,down the road you are bound to want to add something,like USB outlet.

I absolutely agree and this is what is have done on my boat TWICE! BTW I have been told that those 3 way crimps do not comply with ABYC rules so should not be used. And certainly putting 3 or more wires into one crimp is not ABYC approved. As an aside I installed a 12 circuit fuse block near my nav station expecting to use 2 or 3 fuses, a year later it is FULL.

[Americanrancher]

Originally Posted by Reefmagnet

Jaycar does (did?) have a (IIRC) 8 connection terminal strip that uses 1/4" spade lugs, including a couple of rows dual ganged male lugs. I found these pretty good for use as distribution points. As a plus they were also relatively cheap. Even without the ganged lugs, 1/4" spade double lugs are easy to come by.


I'd also say I prefer the lug connections to screw connections because one issue with all screw terminal strips of the open bakelite frame variety is it is super easy to lose screws into the bowels of the boat if trying to install ring connectors with non magnetic screws using some kind of cockamamie (it seems at times) hybrid philips and pozidrive system. Besides, after many years of bitter experience, if I had the choice between using fork or spade lugs I'd choose the spade lugs every day of the week.

Fork lugs are not ABYC approved anyplace on a boat.

[ashmun]

Response for guyrj33 question, "Why did one fuse get hot and not the other?”:

I believe most fuses are purchased in bulk from over sea and the difference between an ‘off brand’ fuse (the one that got hot) and a branded fuse, like Blue Sea, is quality assurance. So a few dollars more for brand name marine fuses, wiring, and connection is cheap insurance against the #1 cause of boat fires (AKA DC wiring) and often better protection against corrosion.

Wire Sizing apps (DC Wire Sizer, Wire Sizer, Blue Sea Wizard, etc.), web site and Marine DC wiring charts mostly follow marine standards (ABYC E-11, ISO, AUS/NZ, etc.) calculations and derating tables but they can’t account for “variants” (as Blue Sea mentions in their disclaimer. So if a wire has been appropriately sized and is getting warm/hot (good to use a thermo gone on electrical panels, connections and wire), here are some “variants” to look for:

1) Old wire; can have corrosion which will cause voltage drop and heat.
2) Bad crimp; with corrosion will cause voltage drop and heat.
3) Any grease in the crimp; will cause voltage drop and heat.
4) SS washers - can be a big problem.
5) Fusing (especially off-brands) and termination.
6) Duration/Continues Running of High Voltage.
7) Input in the DC wire sizing calculation:
7a) Length matters which is why charts always make you go up a step for between sizes.
7b) Bundles; I used a bundle of 1 for 2 AWG on a given wire but a bundle derating of 2 would require 0 AWG, a bundle of 4-6 requires 00 AWG, a bundle of 4-6 requires 000 AWG, and a bundle of25+ requires 0000 AWG.
7c) Wire Insulation; marine wire standard is 105˚wire insulation but an insulation of 75˚would require 0 AWG, insulation of 80˚would require 1 AWG, and insulation of 90˚would require 1 AWG. Note: basic welding cable (not premium) is usually not 105˚wire insulation.

On our boat (and this is not a general recommendation), we use 2/0 or thicker for short battery, starter, inverter, charging source, and other high amp connections to help cover the “variants”. And we use a class T fuse near the batteries and breakers/ANL at the charging sources (AKA solar panel, chargers, etc.).

[Lake-Effect]

Originally Posted by Americanrancher

Fork lugs are not ABYC approved anyplace on a boat.

Just for the record, fork lugs that have a "lock" feature (eg the tips are bent up, or have thicker leg ends that won't fall off the screw) are permitted by ABYC.



... and Reefie, what is considered a "spade" lug? Those tab-type male/female quick disconnects?

[guyrj33]

Originally Posted by ashmun

Response for guyrj33:

Wire Sizing apps (DC Wire Sizer, Wire Sizer, Blue Sea Wizard, etc.), web site and Marine DC wiring charts mostly follow marine standards (ABYC E-11, ISO, AUS/NZ, etc.) calculations and derating tables but they can’t account for “variants” (as Blue Sea mentions in their disclaimer. So if a wire has been appropriately sized and is getting warm/hot (good to use a thermo gone on electrical panels, connections and wire), here are some “variants” to look for:

1) Old wire; can have corrosion which will cause voltage drop and heat.
2) Bad crimp; with corrosion will cause voltage drop and heat.
3) Any grease in the crimp; will cause voltage drop and heat.
4) SS washers - can be a big problem.
5) Fusing (especially off-brands) and termination.
6) Duration/Continues Running of High Voltage.
7) Input in the DC wire sizing calculation:
7a) Length matters which is why charts always make you go up a step for between sizes.
7b) Bundles; I used a bundle of 1 for 2 AWG on a given wire but a bundle derating of 2 would require 0 AWG, a bundle of 4-6 requires 00 AWG, a bundle of 4-6 requires 000 AWG, and a bundle of25+ requires 0000 AWG.
7c) Wire Insulation; marine wire standard is 105˚wire insulation but an insulation of 75˚would require 0 AWG, insulation of 80˚would require 1 AWG, and insulation of 90˚would require 1 AWG. Note: basic welding cable (not premium) is usually not 105˚wire insulation.

On our boat (and this is not a general recommendation), we use 2/0 or thicker for short battery, starter, inverter, charging source, and other high amp connections to help cover the “variants”. And we use a class T fuse near the batteries and breakers/ANL at the charging sources (AKA solar panel, chargers, etc.).

Hmm ,you repeated the assertion that a fuse can cause a wire to get hot (#5).
But you did not answer the question.
How can one fuse over another cause a wire to get hot?

[Lake-Effect]

Originally Posted by guyrj33

How can one fuse over another cause a wire to get hot?

If it passes more current than it's supposed to. (eg wrongly labelled, or imprecisely made). Or maybe poor conduction at its terminals.

[guyrj33]

Originally Posted by Lake-Effect

If it passes more current than it's supposed to. (eg wrongly labelled, or imprecisely made). Or maybe poor conduction at its terminals.

The original statement said " The cable was fine once the fuse was replaced with brand name (in this case, BlueSea). "

The implication is that the original fuse somehow caused a wire connected in serial to overheat.

Was this a case of the fuse getting warm and transfering heat to the cable?
Was the fuse holder replaced along with the fuse?

Let's let Ashmun answer the question.

[Lake-Effect]

Originally Posted by Americanrancher

And certainly putting 3 or more wires into one crimp is not ABYC approved.

Strictly speaking, ABYC has nothing to say about how many wires can be crimped together in one crimp. But if you're joining more than a couple of thinner wires to a thicker feeder (eg for LED lighting), you will run into sizing and wire protection considerations; ie you have to fuse that circuit to protect the thinnest wire from burning up (exception: short fixture or device pigtails connected to a feeder)

[Orin]

Originally Posted by coopec43

We are only talking about a couple of lights and an oscillating fan in the aft cabin so I'm not looking for an expensive over engineered solution. (I must keep cost in mind).



I've soldered just about all the connections and used heat shrink. Mind you my standards might slip a bit if it was just a light but you can bet everything is "spot on" when it comes to bilge pumps even to the extent of enclosing the soldered join in an air tight junction box.


I've used very few "butt splice connectors" but I have to connect the bilge blower and the fresh water pressure pump. Are you saying those joints would have to be soldered/ heat shrink. (I haven't ruled that out)



Those Wago lever nuts look great but there is no way I could spend $12 on a three way lever nut. I'm looking forward to my visit to Jaycar next Wednesday when I can see what they have to offer.


Thanks for your comment

I wouldn’t say “have to be” but it’s a real PITA trying to troubleshoot the sort of intermittent failure due to high voltage drops that butt end splicing creates when it does give up the ghost. Unless you’ve got it fresh in your mind to replace that.

Even then, I would be doubly careful that the risks for fire were not elevated by placement or higher loads. If you’re doing other electrical stuff I’d add it to the list to swap those out. The solder joint should be placed in an area where the wire doesn’t have to flex and will be supported, but then it’ll let the life of the wire done right.

The wago clips ought to be way cheaper. Somewhere around $.35-85 a connector. Like many things though, it’s a bit more difficult to buy just one for $.35.
Also with those sorts of thing you have to add the incoming wire.

Seen here for $0.80 a piece. Actually cheaper than wire nuts from the same store.
https://www.menards.com/main/electri...838455&ipos=17

[ashmun]

Hi guyrj33, a fault fuse can get a hot a number of ways but in this case I believe the issue was resistance. The heat from the fault fuse also caused the wire crimp on the terminal to get hot and about a foot of the cable nearest to the faulty fuse. By removing the cover on the faulty ANL fuse, the owner was able to temp shoot the fuse, the crimp (mechanical), and the wire. Once the faulty “off-brand” fuse was replaced, the new ANL fuse (Blue Sea), the fuse, crimp and the wire all showed normal temps.

Now if changing the fuse did not bring the temp down, then checking for improper washers on the terminal, for a bad crimp, and faulty/corroded cable would have been the next steps done one by one to isolate the issue. Aside from the temp gun, the owner could have also used a meter to check the resistance and voltage drop.

P.S. I’m not saying a brand name fuse can’t fail or be faulty but most major brand names high a higher level of quality control and assurance.

[ashmun]

An ohms meter reading of the good fuse vs the bad fuse would be another indicator. And my guess on what could cause an ANL fuse to be hot, and mind you I’m not an electrical engineer, would be that either a loose connection, like between the fuse ‘strip’ and the copper or the ‘strip' itself was poor causing the resistance. Ohms law on resistance and heat the primary principle and I’m not sure if Preece’s Law would also apply.

Sorry for my brief responses, my mother-in-law just passed and we’re trying to get the place packed, cleaned, and fixed-up. I was just checking the computer because I’m monitoring ads on Craigslist and MarketPlace to help move stuff out. Thanks.

[ashmun]

One last recommendation: MarineHowTo (https://marinehowto.com/fusing-termi...-voltage-drop/) used to have two great articles on battery connections and fusing (besides other great articles) that are well worth reading. I am not associated with MarineHowTo or BoatWorks, I’m just saying they have great articles, How To’s, and videos.

[Reefmagnet]

Originally Posted by Lake-Effect

Just for the record, fork lugs that have a "lock" feature (eg the tips are bent up, or have thicker leg ends that won't fall off the screw) are permitted by ABYC.



... and Reefie, what is considered a "spade" lug? Those tab-type male/female quick disconnects?

These guys...
[IMG]http://www.arlin.com.au/assets/media/product_images/large/arlin_S2QC-6.3_crimp%20terminal.jpg
[/IMG]

[ashmun]

Hi Guyrj33, opps, I still missed answering some of your questions. I’m must be more tired than I thought.

1) Was this a case of the fuse getting warm and transferring heat to the cable? Yes, the fuse was hotter then the crimps which was hotter then the cable and the heat dissipated on the cable as it went away from the fuse.

2) Was the fuse holder replaced along with the fuse? The ANL fuse was off-brand but the holder was Blue Sea and did not seem to be part of the problem.