Connecting LED dome lights small wires to big wires...

[David M]

Mechanical connectors are required in all USCG inspected passenger vessels....for good reason. No solder joints allowed for power. For data wire soldering is allowed.

[rwidman]

Originally Posted by Dockhead

............... It's not good practice to use a connector made for a larger wire gauge. You can double it back and forth, but that's a bodge -- if the doubled strands are caught better than the strands right at the joint, then it can all pull out.

.

An alternative to doubling the wires is to use a short piece of another wire in addition to the "too small" wire and then cut off the excess.

It's always best to use the right connector but sometimes it's not easily available. In theory (and correct practice) the wires will be properly supported and there will be no strain to pull the wire out of the connector. And if it's properly crimped, this will be essentially a solid wire inside the crimp and part of it can't pill out.

[jkleins]

One of the issues that make this a little more complicated than most of the answers here is that the wiring to the light does not just go to that one light in most boats. The breaker that is protecting that circuit may have other lights, 12v outlets, etc on it. If the OP is just replacing the one light and the others are still the older halogens then the 5 amp breaker may not be enough for the load on the circuit.
The question then is how long do the wires need to be to warrant a fuse specifically for that one light?
If the wires were all housed in the same basic space as the light and didn't contact other materials, would that be a factor in whether to fuse them or not?
Even if the wires were bigger on the outside wouldn't the circuitry inside the light be smaller and susceptible to heating? Is this ok since it is inside the box? Would pulling the smaller wires into the housing be the same?
Those were just some of the questions I had when faced with replacing one of my lights so if there are any experts out there I would love to hear your thinking.

Jim

[Dockhead]

Originally Posted by rwidman

An alternative to doubling the wires is to use a short piece of another wire in addition to the "too small" wire and then cut off the excess.

It's always best to use the right connector but sometimes it's not easily available. In theory (and correct practice) the wires will be properly supported and there will be no strain to pull the wire out of the connector. And if it's properly crimped, this will be essentially a solid wire inside the crimp and part of it can't pill out.

I think I agree with you, and certainly I've done it myself like this, but unless you're at sea with an emergency and a limited electrical kit, why wouldn't you bother to get the right connector? I might even use a block connector temporarily, in such a case, rather than use the wrong connector.

One thing I've noticed with this technique is that the wires seem to break off more easily, when crimped doubled up. Don't know if that's inherent to the practice, but using the right connector, with good strain relief, certainly looks better.

[Rowglide]

Originally Posted by jkleins

One of the issues that make this a little more complicated than most of the answers here is that the wiring to the light does not just go to that one light in most boats. The breaker that is protecting that circuit may have other lights, 12v outlets, etc on it. If the OP is just replacing the one light and the others are still the older halogens then the 5 amp breaker may not be enough for the load on the circuit.
The question then is how long do the wires need to be to warrant a fuse specifically for that one light?
If the wires were all housed in the same basic space as the light and didn't contact other materials, would that be a factor in whether to fuse them or not?
Even if the wires were bigger on the outside wouldn't the circuitry inside the light be smaller and susceptible to heating? Is this ok since it is inside the box? Would pulling the smaller wires into the housing be the same?
Those were just some of the questions I had when faced with replacing one of my lights so if there are any experts out there I would love to hear your thinking.

Jim

So...OP here....
I have 2 circuits, lights only. The lights are are wired in parallel.
Each circuit has 4 dome lights and 2 little LED reading lights(2.4w each)
There are no 12v outlets or any other appendages to these circuits.
But damn are these wires ever small...

[TreblePlink]

Originally Posted by leftbrainstuff

Sea air corrosion, brittle and inappropriate for enclosed spaces. A good crimp tool and good connectors will make a more consistent connection.

Yeah, that's what's preached. But when I was troubleshooting avionics problems in a previous life, I found SO many intermittent problems caused by crimps.

I will say that the type of crimp makes a big difference - those with two "wings" that get folded into the stranded conductor, if done well and visually inspected along with a tug test, are very good. But the plain, simple crimp "butt" connectors can easily develop problems.

Similarly, I still hold that a good solder connection, done well, with good shiny flow will beat a plain crimp for reliability. As with any splice or termination, mechanical support is important.

I suspect that "authorities" recommend crimps largely because so many people don't solder well, and crimping is much more straightforward.

I have no connection to the Powerpole sexless connectors I mentioned earlier, and I'm surprised nobody here commented on them. They are an example of a good crimp connector, with silver contacts, that work well:

[BlackHeron]

Originally Posted by jkleins

The question then is how long do the wires need to be to warrant a fuse specifically for that one light?
If the wires were all housed in the same basic space as the light and didn't contact other materials, would that be a factor in whether to fuse them or not?

/snipped/

Jim

These are called "tap conductors." In the commercial electrical world we have specific rules about how long they can be in different locations and types of circuits depending on voltages, feeders, secondaries, or branch circuits. The taps can be pretty long (6', 10, and even 25') but we are talking about AC circuits of 120volts or more. But they can be of smaller wire than that usually associated with the fuse size at the panel, as long as they have sufficient ampacity to feed the device -usually sized at 125% of the calculated draw of the specific equipment they are hooked up to.

On a boat with 12v or 24v DC these "taps" are really part of the equipment like lights and power sockets, and other devices like meters and gauges and such. If they are permanently attached to the approved equipment then they have been designed by the producer to be of sufficient ampacity and short enough in length to be safe to use with the product.

So the short answer is don't be concerned about the wire that comes with your LED lights or the water pump or whatever device that the device comes with. Size your branch circuit wire according the ABYC tables and take into effect length (voltage drop) and ambient temperature de-rating factors. I'm not a fan of using the 105C ampacity tables because I think it woefully undersizes conductors and never use it even though I use 105C rated wire. I never ever size conductors on any table beyond the 75C table, It's much better to oversize wire than to run it too small any day. You really really really don't want wires running at 105C anywhere on your boat.

In the end you really don't have much control over the taps that come with equipment though. Rest assured that for short distances small wire doesn't make much of a difference in overall circuit resistances.

The biggest deal with smaller wire is getting it terminated properly and strain-reliefed so that it won't get damaged. That's why I like crimp connectors that all enter from one side. Then the wires can be taped together an inch or two up so the smaller conductor doesn't get strain where it goes into the crimp. That's where it will fail if it gets any strain and it can just rip or tear very easily as wire sizes get to and much below 18AWG.

[Lake-Effect]

Nice to see all the old arguments getting aired out

For wire-to-wire connections I kind of like these, too.

Originally Posted by BlackHeron

I like these.

http://a.co/bVp1Qtg

The wires are twisted onto each other, then one of these is crimped over top. You can put in as many wires as will fit after the ends are twisted together. After crimping, I dump glue or sealant into the one open end if I want to waterproof it.

The "adaptor" type butt splices seem fiddly and they're expensive.

[edit]

The biggest deal with smaller wire is getting it terminated properly and strain-reliefed so that it won't get damaged. That's why I like crimp connectors that all enter from one side. Then the wires can be taped together an inch or two up so the smaller conductor doesn't get strain where it goes into the crimp. That's where it will fail if it gets any strain and it can just rip or tear very easily as wire sizes get to and much below 18AWG.

I agree with this too.

[Lake-Effect]

Originally Posted by TreblePlink

... I still hold that a good solder connection, done well, with good shiny flow will beat a plain crimp for reliability. As with any splice or termination, mechanical support is important.

I suspect that "authorities" recommend crimps largely because so many people don't solder well, and crimping is much more straightforward.

You are correct that one reason why crimps are promoted over soldering is because the average person, using the right-sized crimp lugs and a good controlled-cycle crimper set up for those lugs, will most likely make a safe, secure, and lasting connection.

But the biggest reason why the ABYC and others don't endorse twisted and soldered wire connections is that if, because of overcurrent or fire, the solder gets to melting point, the joint is no longer secured mechanically and could burn up or separate, causing bigger problems. This mainly applies to power-carrying wires. Signal-carrying wires are less likely to be overloaded like that, so soldering can be more successful there.

I can solder up there with the best of technicians, but I can make a good crimp connection in like a quarter of the time it would take to do a solder splice, realize I forgot the heatshrink, swear, cut the splice, strip the wires again, splice, solder, accidentally scorch the tubing when i shrink it, etc etc.

[BlackHeron]

Originally Posted by Lake-Effect

Nice to see all the old arguments getting aired out

For wire-to-wire connections I kind of like these, too.



The wires are twisted onto each other, then one of these is crimped over top. You can put in as many wires as will fit after the ends are twisted together. After crimping, I dump glue or sealant into the one open end if I want to waterproof it.

The "adaptor" type butt splices seem fiddly and they're expensive.

[edit]


I agree with this too.

They also make really nice uninsulated ones as well, which are much more tidy when gooped up with liquid electrical tape and then over that shrink-tube is placed and crimped down flat on each end. With heat shrink over everything it doesn't need the plastic insulation on the crimp itself which is a little bulky and the bell-end is a bit too large.

https://www.homedepot.com/p/Gardner-...310C/202526312

In the electrical industry companies make "direct burial" terminations that are like this but instead of using liquid electrical tape they come with a little package of 2-part epoxy potting compound which you squish and mix up inside the packet until the two inner parts are thoroughly combined together. Then you cut off one end of the package and shove the completed crimp right up inside it which then will totally seal up the connection when it is cured.

Finally these kits have some glue-lined heat-shrink that goes over the top of that and protects it physically from damage and adds another layer of moisture-proofing and a plastic shield over the top of everything. At that point the cable can be simply dropped into the dirt and buried at a sufficient depth like it was never spliced. These kits are good up to 600v, and for higher voltages than that they make them with more layers that can be built up to add more insulation. Those are often used on 4160v underground cables feeding the grid behind a neighborhood of residential homes.

This same process when done DIY like I explained above is plenty good enough to make the weatherproof terminations for your nav lights on your bow-pulpit to the boat cable which goes through the deck. It'll shrug off salt water like the cable was never spliced and was one solid piece.

[mitiempo]

Originally Posted by Lake-Effect

.......accidentally scorch the tubing when i shrink it.....

Hard to do when using a heat gun.

A heat shrink butt connector properly crimped is a very good waterproof connection. One I use very often.

[rwidman]

Originally Posted by Lake-Effect

Nice to see all the old arguments getting aired out

For wire-to-wire connections I kind of like these, too.
https://images-na.ssl-images-amazon....QL._SX425_.jpg


The wires are twisted onto each other, then one of these is crimped over top. You can put in as many wires as will fit after the ends are twisted together. After crimping, I dump glue or sealant into the one open end if I want to waterproof it. .

I used these as well as the butt splices and crimp terminals when I was working.

They are OK for something like connecting wires to pigtails at a fixture (like the OP's light fixture) but look pretty sloppy if extending wires, etc. and they are unlikely to pull through a conduit if that becomes necessary.

[Lake-Effect]

Originally Posted by rwidman

[Crimped cap splices] are OK for something like connecting wires to pigtails at a fixture (like the OP's light fixture) but look pretty sloppy if extending wires, etc. and they are unlikely to pull through a conduit if that becomes necessary.

This is getting into the style area a bit... in some electrical standards, like house electrical, you're not allowed to bury a splice; they must only be made in suitable enclosures and must remain accessible for future inspection and service.

I like to carry that thinking into boat wiring as well. I try not to put in then pull through a splice that will become inaccessible.

Second, when you aim to make splices only in accessible spots, and you're planning for cap splices, you're forced into leaving an extra 4 to 6 inches of wire ends to make the splice on, so you know you have a bit of access for future re-splicing or changes, and that the wires aren't under tension at that point. And it's easier to crimp that one cap on twisted wires than it is to try and do two crimps on a butt splice,

Yes, a well-made inline butt splice that's pulled snug occupies less space than a bundle of pigtails... but you'll end up running a new wire if you ever have to replace or alter that splice.

[mitiempo]

Originally Posted by Lake-Effect

Yes, a well-made inline butt splice that's pulled snug occupies less space than a bundle of pigtails... but you'll end up running a new wire if you ever have to replace or alter that splice.

Don't pull it tight. Leaving a service loop is the proper way to do this.

[BlackHeron]

When I totally rewired our boat I ripped everything out and started fresh with flexible PVC conduit and PVC electrical boxes from the panel out to various locations. I pulled individual stranded wire in pairs, 4 circuits per box. All splices are inside the boxes and boat cable that went out from the boxes was never more than 4-5 feet long and was run through gland connectors. Any cable was strapped and secured within 6" of the junction box and every 18" after that. These junction boxes are pretty water tight and have gasketed covers. There are no joints outside of the junction box except for right before the light or whatever electrical device where the boat cable meets the wire of the device, where I used butt splices and marine shrink tube. Some devices had terminals and in that case the boat cable went directly to those terminals with a proper sealed ring connector.

As far as I'm concerned running wires all around a boat in cable is just as bad as running Romex in a house. I don't care if it is stranded and tinned. It's still Romex crap to me. Put it in conduit and boxes, and protect those wires and splices.

https://www.homedepot.com/p/AFC-Cabl...2-00/202286718

There is almost no