Why are wire nuts disliked in boats.

[sdowney717]

Anytime I have used a wire nut in the boat, I have first solder tinned the wire ends. I have about 4 in use. Other places, to join wires, I have used copper crimps, then heat-shrink them. I have also put marine grease inside wire nuts, and honestly those few wire nutted connections have been fine.
From my testing there have been no problems.
Maybe its the way everybody uses them, just screwing onto bare wires?

 

[bayview]

IMO they can loosen with vibration. Frequent temperature variations probably don't help either.

 

[TJM]

Disliked is putting it mildly. It might be do to the way DIY'ers can go to any big box store and use them.
Exposure to corrosion is a big issue with the open ends.
The potential for trapped water in the cone ?
The possibility of them untwisting causing a shorted condition on a possible critical piece of equipment ?
Galvanic corrosion inside the wire ?
Just to name a few.

 

[O C Diver]

While I don't know for sure, I would guess wire nuts aren't approved for anything that moves (may be subject to vibration) as there is no locking mechanism to keep them from loosening. They're certainly not approved for any kind of vehicle, airplane, or boat.

Ted

 

[bayview]

Over time I have found that following the codes is generally better than what somebody can get away with. If I saw wire nuts on a boat I was considering I would wonder what else was done incorrectly.

 

[Shrew]

Over time I have found that following the codes is generally better than what somebody can get away with. If I saw wire nuts on a boat I was considering I would wonder what else was done incorrectly.

I found 2 buried in the lower helm while I was doing an electronics install this winter. I ended up having to rewire most of the lower helm in the process. It still nags me where else I might find similar work.

 

[diver dave]

vibration. read this:

https://forums.mikeholt.com/showthread.php?t=94443&page=15

industrial electricians even resorting to using tape and then a tie wrap over it all when dealing with shaking wire nuts.

 

[stubones99]

Plus, if they end up pointing down, salt water collects in the cup and will speed up corroding the wires.

 

[sledge]

Plus the latest adhesive heat shrink butt splice connectors are easy to buy in bulk, relatively easy to use (with a correct crimping tool), and they allow you to sleep much easier at night....

 

[diver dave]

Plus, if they end up pointing down, salt water collects in the cup and will speed up corroding the wires.

good point. while on a similar subject; one must not use the "back stab" feature on receptacles. I won't have that even in my house.

One time, I had a auto grade wire running in the boat. Salt water found a pinhole in the insulation, then migrated +/- a foot either way, and actually opened up the electrical path. Essentially no visible damage. Thus, the reason for 600V rated insulation for boats. Nothing to do with applied voltage; its the applied sea water.

 

[sunchaser]

Humm, properly crimped wires held by nuts used all over on every vessel for larger wires. As with everything, and stealing PSN’s wording, it just depends.

 

[diver dave]

Humm, properly crimped wires held by nuts ....

I'm not sure what that means.

 

[STB]

Just twisting, as in household use, doesn't reliably hold in vibration, even if taped or heat shrink taped outside the nut.

Soldering generates stress points where the eire is more subject to failure and also makes the nut bite less into the wire.

Also remember that home wiring is solid and boat wiring is stranded to let it bend more easily -- but which also lets wire nuts damage the thinner constituent wires more easily.

Crimping provides a better connection with less damage and when combined with a heat shrink sheath provides a strain relief that prevents the stress at the crimp. A similar arrangement could be made for soldering but would require similar consistency in form, which is unlikely by hand without a jig ornm controlled heat, timing, volume, etc.

 

[STB]

I can also add that i just got through debugging an autopilot failure that delayed the departure for a long trip of a dock neighbor and stumped an electonics shop.

Corroded wires in wire nuts were half of the failure. Wire damaged inside the sheath at a stress point was the other half. And a mislabelled breaker that controlled the autopilot pump but not controlled head or computer was a confounding factor (it was labelled deck lights), as were wires changing colors in odd places.

 

[syjos]

There are wire nuts with set screws but still not recommended.

Non adhesive lined crimp connectors can get water in there too.

 

[Comodave]

I agree with the negatives stated above but would add that if you sell the boat, the surveyor will call them out if he/she sees them. It just adds more potential for the buyer to say, humm wonder what else is not done properly? Besides why not just do it correctly? It isn’t any more difficult.

 

[AusCan]

Personally, I'd prefer wire connections that were soldered with a wire nut over cheap crimp connections done poorly. But the wire nuts are more obvious, so they tend to get the bad rap.

 

[syjos]

For splicing cables, I use these.

They are filled with gel to keep water out and the clamp screw has a waterproof cover.

These are rated for wet areas.

I buy them at an electric supply distributor.

 

[psneeld]

I get it.... But the reality is after working on many boats....I have seen failures in every other kind of connector (except maybe heat shrink crimps...probably because they were rare till recently)....and yet on those same boats the wire nuts connections were still OK.


ANY connector poorly done is an issue....and there are lots out there....not just wire nuts which some boaters probably have the most experience with.


Not suggesting their use, but their bad rap is like many other boating no no's....not as bad as they are made out to be. Or look at it as ....many shouldn't work on their boats including many pros.

 

[Brooksie]

Illegal for many reasons but holding water and not vibration proof are near the top of the list. Most common wire nuts have plated steel guts too.

 

[Comodave]

Why are there so many problems, apparently according to this thread, with crimp connectors? I use a ratcheting crimper that will not release until the crimp is probably done. Then I pull pretty hard on the wires to check. If used properly crimp connectors are extremely reliable. Then heat shrink the connectors and you have a solid, reliable and waterproof connection. Done. Why would anyone even consider using a wire nut instead?

 

[angus99]

 

[Ski in NC]

Most wire nuts the inside coil is not corrosion resistant. Steel I think.

If you heat shrink the two wires, that does not close the gap between the pair of wires. It will not seal the connection.

The grease would help. But I still do not want them in the boat. Might be as good as any other connection, but do not like the stigma.

 

[syjos]

Why are there so many problems, apparently according to this thread, with crimp connectors? I use a ratcheting crimper that will not release until the crimp is probably done. Then I pull pretty hard on the wires to check. If used properly crimp connectors are extremely reliable. Then heat shrink the connectors and you have a solid, reliable and waterproof connection. Done. Why would anyone even consider using a wire nut instead?

I agree 100%

Most problems with crimp connections are attributed to several practices.

Most boaters use the less expensive, more commonly available wire crimper - wire cutter combination tool, which does'nt crimp the plastic around the connector. The crimping quality varies with the strength of the operator's hand. Pull on those connections and they sometimes fail.

The ratcheting crimpers place a specific pressure on the crimp, makes a wider crimp with more contact area and crimps the plastic around the connector.

The other issue is the connectors themselves. The 3M connectors are very well made, tinned and the plastic can be crimped. The other connectors that are found in auto parts stores and elsewhere are usually not tinned and the plastic around the connector does'nt crimp well.

 

[Maerin]

Illegal for many reasons but holding water and not vibration proof are near the top of the list. Most common wire nuts have plated steel guts too.

Perhaps splitting hairs, but there's nothing illegal about using wire nuts. There's no law prohibiting their use, there's no entity with enforcement powers. They *are* specifically prohibited in ABYC standards, but that's a standard or recommendation, not law. Lots of folks refer to ABYC compliance in relation to legality, it's a voluntary standard, not to be confused with building/electrical/plumbing *code* which is codified by law, and has entities with enforcement powers e.g. your local building code enforcement official. Officer of the court. No parallel agency exists in the boating world, other than USCG, but that's a different can of worms.

 

[syjos]

Perhaps splitting hairs, but there's nothing illegal about using wire nuts. There's no law prohibiting their use, there's no entity with enforcement powers. They *are* specifically prohibited in ABYC standards, but that's a standard or recommendation, not law. Lots of folks refer to ABYC compliance in relation to legality, it's a voluntary standard, not to be confused with building/electrical/plumbing *code* which is codified by law, and has entities with enforcement powers e.g. your local building code enforcement official. Officer of the court. No parallel agency exists in the boating world, other than USCG, but that's a different can of worms.

Surveyors will make a deal about it on the report. Insurance and banks will want the issue rectified.

Boat US surveys my boat every 10 years and things like wire nuts would require corrective action.

 

[sunchaser]

I'm not sure what that means.

I’m being purposely obtuse. Naturally, a home style wire nut is a bad idea on a boat. But many properly crimped wires held in place by nuts or bolts give problems as well for a whole host of reasons.

But connections of any type allowed to get wet will eventually become problematic. It would seem a failed connection requires a bit of thought as to why it occurred.

A wire nut in a nice dry setting would likely outlive a “Normal” connection getting doused with salt water. It depends —-

 

[sdowney717]

I do a lot of soldering of wire ends. Frequently have crimped then soldered. Sometimes have just twisted and soldered! But I tell you I dont have any failures with anything and I have owned this boat since 1998 and rewired a lot of it. I do not particularly like those plastic collars, I sometimes prefer to remove them, crimp , solder, then heat shrink. And nothing ever gets wet, that is odd, why do people talk about wet wiring?

There is only one possible place for wet wiring, and that is wiring and terminal strip blocks under the floor in the bilge areas. I dont know how your boat is made, but mine has 2x4 floor framing holding up the plywood floors and I put those terminal strip blocks on them and they are foot above bilge water. Its just not much of a problem even there and when it is a problem, I redo whatever it needs. I have 5 bilge pumps and pump switches and I just consider it normal maintenance.

I can understand hard spots created by soldering,, which can snap the wire apart due to being bent back and forth, but its rare, and ought to be as the entire length of wire allows for flex.

And the few wire nuts have been fine and easy enough to replace if I had too. The vibration and wire moving around cause boat moves, not sure I can agree with that. Typically wires are going into boxes, and the boxes have a clamp to keep the wire steady, so its not moving inside the box.
I honestly think the corrosion issue is true, and the big reason not to use them as is. The inside of wire nuts is steel and can rust. But if you put marine grease, then they cant rust. The other is supposedly a wire nut can cut the wire strands, but that idea is over rated and if you solder the ends, wont happen.

Of course you cant fight the tide of opinion.

 

[Boatfever]

Just twisting, as in household use, doesn't reliably hold in vibration, even if taped or heat shrink taped outside the nut.

Soldering generates stress points where the eire is more subject to failure and also makes the nut bite less into the wire.

Also remember that home wiring is solid and boat wiring is stranded to let it bend more easily -- but which also lets wire nuts damage the thinner constituent wires more easily.

Crimping provides a better connection with less damage and when combined with a heat shrink sheath provides a strain relief that prevents the stress at the crimp. A similar arrangement could be made for soldering but would require similar consistency in form, which is unlikely by hand without a jig ornm controlled heat, timing, volume, etc.

/\/\/\/\/\
This (bolded type)
Wire nuts are for solid wire. Sure, a lot of us have made them work with stranded but the propensity for loosening, especially in a vibrating environment, is there. As well as the above mentioned wire damage on fine stranded wire. I've never used them on a boat. Then there is the obvious corrosion problem many are mentioning.

 

[psneeld]

Not sure they are illega on recreational boats, but there are better options.