NMEA 2000 Connector Question

[svenskflicka]

I used these on my SIMNET (NMEA2000) masthead wind sensor successfully.

Originally Posted by Dsanduril

Just came across these self-soldering heat shrink butt splices in my business life. Splice/solder/heat shrink all in one unit, using only a heat gun. No mechanical connection however. Seem to work well on land, anyone actually used them on a boat? Seems like they might be useful in this scenario.

[s/v Jedi]

Field attachable connectors from Maretron work like a dream. I can’t see how they don’t work for someone who can follow the instructions

Here’s a tip: buy long ready-made cables. Cut them in half so you can use both ends and in the case of the arch of the OP: feed the cable from outside to inside so that the factory molded connector is outside and the field attachable connector inside.

Also: the cable should already have tinned conductors. You should not use a soldering iron to tin those before attaching to the connector with screw terminals. This creates hard spots and the connector is not designed for it. What is crucial is to strip the cable and conductors conform instructions. No bare (stripped) conductor should stick out the terminals.

[DGH]

What happens if I leave a tee on the backbone without any dropper or device attached?

[bergius]

Originally Posted by DGH

What happens if I leave a tee on the backbone without any dropper or device attached?

Nothing, as long as the open connector doesn’t get wet and maybe cause a short. I’d recommend adding a blind cap.

[s/v Jedi]

You may want to consider to just remove the T. If all is well, you should be able to attach the backbone connectors to each other without the T being the coupler.

[DGH]

Thank you Bergius and Jedi.

[Bella Donna]

I have used those self-soldering heat shrink butt splices, and they seem really good if you can manage to do it well. My biggest challenge is whe is trying to do them by myself. Because you need to have both wires inserted and positioned correctly, even having two hands for the job is a bit challenging--if you're holding one wire in each hand, the splice connector kind of floats between. When doing the heating you can't hold the connector. So even with four hands it's not easy, especially if working in cramped quarters. Before I do them again I'm going to get myself one of those multi-leg spider things with alligator clips. I think that will make the jab a lot more

[s/v Jedi]

Originally Posted by Bella Donna

I have used those self-soldering heat shrink butt splices, and they seem really good if you can manage to do it well. My biggest challenge is whe is trying to do them by myself. Because you need to have both wires inserted and positioned correctly, even having two hands for the job is a bit challenging--if you're holding one wire in each hand, the splice connector kind of floats between. When doing the heating you can't hold the connector. So even with four hands it's not easy, especially if working in cramped quarters. Before I do them again I'm going to get myself one of those multi-leg spider things with alligator clips. I think that will make the jab a lot more

Yes, I used the helper clips too, plus I cheated with a bit with my flux-pen.

But remember that this is low melt temperature solder and you can not use it for high amperage circuits. I use them for data and low power LED lights only.

[Bella Donna]

I would say that if your wire is in danger of melting the low temperature solder due to current flow (amperage), your wire is undersized. The maximum temperature that wire is rated for is 90 deg C. The minimum upper temperature that these type of connectors are rated for is 125 deg C

[s/v Jedi]

Originally Posted by Bella Donna

I would say that if your wire is in danger of melting the low temperature solder due to current flow (amperage), your wire is undersized. The maximum temperature that wire is rated for is 90 deg C. The minimum upper temperature that these type of connectors are rated for is 125 deg C

The problem is melting the solder before the fuse protects the wire. Fusing values for wiring do not consider low melt solder.

[Bella Donna]

Under what circumstances would you use a fuse that will allow the wire to get to 125 deg C before blowing if the wire is rated for 75 deg C or 90 deg C?

[s/v Jedi]

Originally Posted by Bella Donna

Under what circumstances would you use a fuse that will allow the wire to get to 125 deg C before blowing if the wire is rated for 75 deg C or 90 deg C?

Most wiring on boats is 105 degree Celsius and at that temperature low melt solder has lost most mechanical properties. The fusing values as used in the industry simply do not consider low melt solder. I don’t think it is mentioned as not being allowed, but this is because they never expected people to use this for power circuits.

You crimp.

[Bella Donna]

According to a quick search, you're right. 105 deg C does seem to be quite common, if not standard. It's just really hard for me to imagine that anyone would design their circuits and fuse them to allow them to be so hot that you could boil water on them or even to be too hot to touch! That just seems like pushing things to extremes. Wouldn't we all be better advised to use larger wire?

[s/v Jedi]

Originally Posted by Bella Donna

According to a quick search, you're right. 105 deg C does seem to be quite common, if not standard. It's just really hard for me to imagine that anyone would design their circuits and fuse them to allow them to be so hot that you could boil water on them or even to be too hot to touch! That just seems like pushing things to extremes. Wouldn't we all be better advised to use larger wire?

Sure, but this isn’t for normal circumstances, it is for when there is a short somewhere. Before the fuse blows the wire can get that hot, not during normal operation.

[Bella Donna]

I'm curious how you would select your fuse rating. For example, if you are running #12AWG marine wire, what fuse would you use?