Methods of connecting two led cabin lights to one switch

[Boater Sam]

The industry would seem to disagree. Solder joints apparently don't do well where there is potential for movement such as on boats, and can cause broken wires or strands*. I can't see it being a huge issue if done well, but taken at scale these things generally are not done well. I used Wago connectors for the first time this year and was pleasantly surprised how good and cheap they were (they are genuine, but still inexpensive). The main issues with them are needing the space and needing the correct size. I absolutely hate standard insulated crimp connectors, even with good tools they fail to crimp tightly too often. Other crimps are fine though, and these days I prefer a nicely specced connector with crimped pins for most jobs, the downside to which is I now have 6 crimp tools and a locker full of various connectors ?

*someone like Paul will hopefully be along with the real explanation shortly

Twaddle. The world used to run on soldered joints till the nay sayers started making money out of selling fancy connectors.
The USA runs on twisted wires and screwits.

 

[PCUK]

As said, just put two wires into one crimp terminal, use the next size up to accommodate the size of the two wires. This is a very simple job and you are over-thinking it!

 

[lustyd]

Another option if 2 wires might become 4 wires in future is these studs, which you can fit in behind the panel. They're nice and neat and I've used them to give me one "electronics" switch to turn on the various gubbins with one switch.
https://www.amazon.co.uk/gp/product/B07V2N7M24

 

[Stemar]

This is how I'd do it. Simple and flexible

Double spade connector, 10-pack

 

[PaulRainbow]

Would there be objection to one of these in a dry location?
3M, Scotchlock 560B Tap Splice Connector, Blue, Insulated, Tin 18 → 16 AWG | RS Components (rs-online.com)
(Other sizes/colours available I believe)

These belong in the skip i'm afraid, horrible things.

 

[PaulRainbow]

Twaddle. The world used to run on soldered joints till the nay sayers started making money out of selling fancy connectors.
The USA runs on twisted wires and screwits.

Not on boats they don't. I also suspect they don't use them on car, planes, or most other installations.

 

[PaulRainbow]

As said, just put two wires into one crimp terminal, use the next size up to accommodate the size of the two wires. This is a very simple job and you are over-thinking it!

This can be acceptable, but you cannot usually get the insulation in correctly. So, strip some extra insulation back (or the wires don't go into the crimp far enough), crimp as usual, then put heat shrink over the whole of the connector and about 20mm of the insulated wires.

 

[PaulRainbow]

He's been missing for a while. Couldn't find him on the members list the other day, so I assume he has left? A great shame, but he and a few others did seem to get into a slanging match quite often. All in my opinion of course.

Still here, just been very busy with work.

 

[Wing Mark]

I think there is something to be said for not having all the cabin lights on the same fuse.

I've found that it doesn't matter so much what means you use to join wires, what matters is whether you do it properly, whether the wires are stressed afterwards, protected, kept dry enough etc etc.
I've done some of my cabin lights via a low dropout regulator IC, because the 10W LED fixtures would have been over driven at 14.4V charging voltage. That feeds a row of 2A fuses on a PCB, with screwdown connections for individual wires. It sits in the locker next to the switch panel.
It's not ideal, but there was little space behind the panel and some of the wires were quite short.

 

[PaulRainbow]

If i was wiring in a number of lights in one cabin i would only run a pair if wires from the switch, to the closest light, then loop to the next, the next etc (as suggested earlier).

1.5mm wire would be good enough for more LED lights than you'd be likely to fit on most moderate sized boats, but it's a good choice, as it's robust. Depending on the connections at the lights, i might use the aforementioned Wago connectors (3 way) or i might use insulated crimps (blue crimps and heat shrink work nicely for a pair of 1.5mm wires).

Soldering is acceptable, if done correctly. All too often it isn't done well, whereas most DIYers can make a decent job of a crimp. The main reason we don't do a lot of soldering professionally is the time it takes.

 

[Alex_Blackwood]

As said, just put two wires into one crimp terminal, use the next size up to accommodate the size of the two wires. This is a very simple job and you are over-thinking it!

Very bad practice to crimp two wires in a single connector.

 

[Hydrozoan]

Personally I wouldn't. ... My preference these days is a Wago though

I take your and Paul's objection, and have only used them on one or two occasions when space and access were very limited, (which I thought from the OP might be the case here) - but that was before the small Wago lever connectors, I think.

On the equally few occasions when I've put two wires into one crimp, which I also avoid whenever possible, I've also carefully opened up the strands and re-stranded them together before crimping (with a ratchet crimper) - but that's perhaps overkill.

 

[PaulRainbow]

Very bad practice to crimp two wires in a single connector.

I've heard this said before Alex and i'm going to disagree with you on this one.

A blue, insulated crimp is generally used for 2.5mm cable, which is typically 50 strands of .25mm wire. 1.5mm cable is typically 30 strands of .25mm wire. So two x 1.5mm cables will consist of 60 strands of .25mm wire, as opposed to the 50 strands of .25mm wire that a single 2.5mm cable will consist of.

Those extra 10 strands of wire fit perfectly OK in the connector and can only make for a slightly tighter crimp, maybe.

Providing the connection is covered in heat shrink it's perfectly OK.

A proviso being that the two cables should both use the same size of individual wires.

 

[Fantasie 19]

Look up "piggyback spade terminals" on Google Images and see if they'll do what you need.

They come in the three sizes of blue/red/yellow crimp and Halfords, Amazon and 12voltPlanet all stock them,

Beat me to it... I used one of these.. Female Spade Terminal with Piggy Back Male... apparently...

 

[Hydrozoan]

Beat me to it... I used one of these.. Female Spade Terminal with Piggy Back Male... apparently...

View attachment 127590

Crimp connector adapters are also available, both double male to female (61765-1 | TE Connectivity Female to Male Spade Connector, Adapter, 6.35 x 0.81mm Tab Size | RS Components (rs-online.com) ), and double female to male (RS PRO Female to Male Spade Connector, Adapter, 6.35 x 0.8mm Tab Size | RS Components (rs-online.com) ).

 

[steve yates]

This can be acceptable, but you cannot usually get the insulation in correctly. So, strip some extra insulation back (or the wires don't go into the crimp far enough), crimp as usual, then put heat shrink over the whole of the connector and about 20mm of the insulated wires.

Thanks Paul, will do, I'm heat shrinking everything
On the subject of connections, does anyone smear vaseline over their terminals where connections are made? I remember hearing vaseline was good at keeping moisture out but not sure if there's any truth to this?
All my connections are crimped and covered in heatshrink.

 

[thinwater]

Very bad practice to crimp two wires in a single connector.

Explain why, with references. Seriously.

Obviously, heat shrink is required for strain relief, since the strain relief crimp will likely be substandard. Normally, there will be enough adhesive to fill around the wires, stabilizing them. And this is, after all, exactly what pigtail crimps are.

I have had numerous soldered joints fail from either fatigue or a combination of corrosion and fatigue. Never had crimp fail on a boat. I'll solder if the wires are small and there is no other good option, but only then. And always suport with heat shrink

Wago connectors do not meet the pull-out strength requirements for ABYC. They are actually much weaker than wire nuts. Chockblocks with pressure plates do. Either way, you need strain relief. That said, I have used them a few places, including an anchor light 3 years ago, without failure. They are fast. But mostly I use them for testing and dry running things, for which they are very handy.

Yes, any waterproof grease will reduce corrosion. Whether that is a big deal in the cabin near a light depends on how many leaks you have.

 

[Kilo]

Thanks Paul, will do, I'm heat shrinking everything
On the subject of connections, does anyone smear vaseline over their terminals where connections are made? I remember hearing vaseline was good at keeping moisture out but not sure if there's any truth to this?
All my connections are crimped and covered in heatshrink.

You can buy heat shrink with a form of glue inside that will give a sealed finish, not suitable for continuous immersion but better than vaseline. I'll find a link later.

 

[PetiteFleur]

I've used both Wago connectors as well as a professional crimper, acquired years ago when I had a job abroad and had to do a rewire. I use whichever is suitable at the time. I do have a 12v soldering iron but it's not very good.

 

[Boathook]

Thanks Paul, will do, I'm heat shrinking everything
On the subject of connections, does anyone smear vaseline over their terminals where connections are made? I remember hearing vaseline was good at keeping moisture out but not sure if there's any truth to this?
All my connections are crimped and covered in heatshrink.

I use contralube, especially where the connections are more 'outside'. Contralube is expensive but you don't require much.