wire nuts come loose?

[GlennWest]

Still using my remaining dometic heat pump. Started tripping breaker. DW says she smells something hot like wires. She has a great smeller. I crawl up and check it out. This unit was new 3 years ago. The 110v connection was connected with wire nuts. I has it installed as I was working 7 days a week. What I found was the hot leg had burned the wire nut off and shortening out.Wire was burnt. I replaced burnt wire and cleaned the solid wire hot supply. Wired nutted back. Not getting hot now. My question is, is wire nuts a good practice in this area.  There is some vibration in these units. Or was it just not tight enough? 

 

 

 

 

[Bobbyb]

I do not know if wire nuts meet the RV code. On our 08Dynasty MH they used wire nuts but all are taped as well. I was taught to always use a plier to twist the wires first. If you don't like wire nuts there are some cool alternatives. You can find them at Home depot. They are a small plastic block and you simply strip your solid wire and insert. You can get them  with various wire capacity. I think some of them are approved for stranded wire. I am sure an electrician will jump in and correct me!

[GlennWest]

Well supply wire is rolex, solid wire. AC is stranded wire. Can not really twist this together. I agree with solid wire. Twist together with pliers and tape or wire not for cover.

[Pat & Pete]

I have made connections that are of solid and stranded wires . I twist the stranded wire , so the stands are twisted together . 

Then the nut goes on with the solid and twisted stranded wires together , tight as I can get it . Usually no problems . 

I recall ending up soldering previously wire nutted connections . But , those are pretty rare .

I use wire core wire nuts . They seem to be best . 

 

[GlennWest]

It may very well not been tightened properly. I didn't do it, so I can't say yea or nay. It is tight now but this happening had me wondering. If both solid would not even concern me.With DC connections I always use butt splice connectors with stranded wire. 

[DanZemke]

My recollection is that wire nuts are designed for solid wire connections.  Something like these are relatively inexpensive, easy to install and extremely reliable.  I happen to have just used one to fix a wire driving one of my Volvo 770 mirrors. I used a standard heat gun (Weller 120 volt) to melt the solder and shrink the tubing.  Here's an example of a "kit", but you may want to pick a version specifically suited for the gauge of wire needed.

Solder Seal Wire Connectors

https://www.amazon.com/dp/B07H2QZ1HR

[GlennWest]

Had never seen those. Neat.

[Chad Heiser]

Anytime I use a wire nut in a mobile environment (like my RV), I always tape it after I tighten it.  The vibration of the RV when in motion can loosen the wire nut over time and taping helps to prevent this.

[GlennWest]

I never did find a metal sleeve in there. Did find a melted wire nut but no metal sleeve that is in the ones I use. I have seen wire nuts that were all plastic. He may have used that.

[Pat & Pete]

34 minutes ago, GlennWest said:

I never did find a metal sleeve in there. Did find a melted wire nut but no metal sleeve that is in the ones I use. I have seen wire nuts that were all plastic. He may have used that.

The core isn't so much a sleeve as it is a coil , only cone shaped .

I know the smaller sizes are usually all plastic . 

[beemergary]

Wire nut story. No hot water just warm in house with electric hot water heater. Just use light tester at elements and there's power. Change elements and still just warm water. Then change temp. rheostat. Still warm water. Go look at water heater meter and its turning real slow. Cut the tag on box and open door. Electric Co. can remotely cut your power when a high demand. They had wired the receiver box into meter box with wire nuts and one must not been tight and got hot and came off. Moral of story-If I had used a 220volt tester would have known only getting 110 volts. The 110volts would go into element one side and out the other. I like to just use butt connectors with shrink tube if all possible and No all plastic wire nuts. To be old and wise had to be young and stupid.

[57becky]

Wire nuts are not designed to carry current from one wire to the other.  They are strictly intended to maintain pressure on the two or more wires so they stay fully in contact with each other.  If the nut is loose, it was not properly installed.  For 120 volts, the only wire nuts to use have the metal wire inside.  The only place the all plastic nuts should be used is low voltage, such as thermostat wires or communication wires.

[Sehc]

dirty copper will cause many problems. wire nuts should not be used in a vehicle. i wounder what is used for that "solder" that melts at 138C,  280F. My tin solder melts over 400F.

[oldjohnt]

19 hours ago, GlennWest said:

My question is, is wire nuts a good practice in this area

Glenn, great question. In my professional life in the electrical industry (Power Distribution) it was my experience and observation that when such a failure occurred, IT WAS OFTEN "NOT" THE WIRE NUTS THEMSELVES BUT THEIR IMPROPER INSTALLATION. If installed PROPERLY I saw few failures. In the workshops and seminars and when we instructed our electricians and contractors we stressed for added mechanical strength  there be a few extra wire turns outside the nuts themselves and where room allowed there be adequate slack and loops to allow for vibration and expansion/contraction. While typically not required a person could solder wires then then use wire nuts for added coverage, mechanical strength and protection, with tape to follow, but proper wire nut installation with added twists and expansion loops for vibration and expansion/contraction was all "usually" necessary...……. 

 

John T Longggggggggggg retired n rusty electrical engineer NOT up on the latest Codes and practices SO NO WARRANTY, things may have changed grrrrrrrrrrrrrr lol  

[GlennWest]

also this is stranded wire to solid wire. Doesn't twist well. 

[Kirk W]

14 hours ago, beemergary said:

Wire nut story. No hot water just warm in house with electric hot water heater. Just use light tester at elements and there's power. Change elements and still just warm water. Then change temp. rheostat. Still warm water. Go look at water heater meter and its turning real slow. Cut the tag on box and open door. Electric Co. can remotely cut your power when a high demand. They had wired the receiver box into meter box with wire nuts and one must not been tight and got hot and came off. Moral of story-If I had used a 220volt tester would have known only getting 110 volts. The 110volts would go into element one side and out the other. I like to just use butt connectors with shrink tube if all possible and No all plastic wire nuts. To be old and wise had to be young and stupid.

Mind explaining this one? If you remove one side of a 240V circuit? ?

[DanZemke]

Quote

i wounder what is used for that "solder" that melts at 138C,  280F.

Interesting question.  I didn't know the answer either but found it in Wikipedia.  The alloy is 58% bismuth and 32% tin.

Go to the linked page and search on: 138, to see the information in the table: https://en.wikipedia.org/wiki/Solder

[Pat & Pete]

3 hours ago, GlennWest said:

also this is stranded wire to solid wire. Doesn't twist well. 

Like I said , twisting the strands of stranded wire together makes it much easier to twist mismatched wire together .Twisting stranded wire makes that wire stronger , more stable .

[Randyretired]

Using wire nuts to secure solid to stranded wire is common practice.  Many light fixtures for instance use stranded wire to solid, romex wire.  It is bit tricky though and human caused failures do happen. A friend pulled into camp with us and literally crawled out of his MH.  The platform over the steps would not retract.  The problem was a wire nut that failed to secure the ground.  That wire nut was wrapped with tape.

[rpsinc]

7 hours ago, Sehc said:

wire nuts should not be used in a vehicle

I agree.  Their intended use is where no motion will be experienced.  I could see how crimp caps might work in RVs but never wire nuts.  Butt splices are a better choice.

[ALLOY]

I was taught to strip the wire 3/4" the length of the wire nut and twist the 2-4 wires until there is 1-2 turns/twists of the (insulated) wire outside of the nut.

When crimping solid wire it is critical that the correct (not universal) crimping dies are used.

Electrical tape is temporary and it leaves a sticky mess.

Interesting fact....In a boat both the AC and DC wiring is stranded (boat cable) but AC in a RV is solid.  In boats people will use the crimp connectors meant for 12VDC on the AC which is a no no as the 12VDC crimp connectors are split.

 

 

 

 

 

 

[oldjohnt]

Again its often  NOT  the wire nuts but improper installation the problem. A problem I saw often when they were used to splice stranded to solid wire was the stranded got pushed down versus it and the wire nut and the solid all joining together !!!! IMPROPER INSTALLATION. If I were using this (solid to stranded) in a critical hard to get at high current vibration application Id consider twisting the wires together then soldering then apply the wire nut. Still have an extra wire loop for vibration and expansion/contraction protection. A splice like that done correctly should be near bulletproof.

John T  Long retired n rusty, things change so no warranty   

[j2catfish]

I have found when connecting stranded to solid wire with wire nuts, it is best to strip slightly more insulation from the stranded wire. Allow the end of the stranded wire to be some longer than the bare solid .  To me, that ensures that the stranded wire properly contacts the solid wire.  Seems to me that taping the connection used to be Code but somewhere along the way that requirement was deleted.

Catfish (young retired electrician)

[beemergary]

On ‎12‎/‎13‎/‎2018 at 12:38 PM, Kirk W said:

Mind explaining this one? If you remove one side of a 240V circuit? ?

You get 220 volts by 2 110 volt lines. Your house has 220 volts from 2 110 lines. A 110 circuit breaker get power from one leg in box. A 220 circuit breaker gets power from both legs. A hot water heater element is 220 which is 2-110 lines going to it. My hot water heater would only get warm because was only getting 110 and not 220. By just using a light meter the 110 will feed into one side of element and out the other turning on the bulb on both sides but only one side is getting power. Lesson learned that day.

[Kirk W]

3 hours ago, beemergary said:

My hot water heater would only get warm because was only getting 110 and not 220.

. The reason that I asked for the explanation is that as a career electrical service technician, I think you missed something. A house has two legs from a 240V transformer that has a center tap tied to neutral and each phase is then 120v to the neutral line. Your water heater element has what amounts to +120V on one end of the element and -120Vtothe other, giving you an effective voltage of 240V. (As AC electricity it is actually two legs that are 180 degrees out of phase but they work in a push/pull effect.) If you remove either of the legs from that element, the result is that no current can flow so no heat. You must have had a bad connection that was dropping about half of the voltage and so lowering the heat capacity. In such case, you would have measured somewhere around half voltage across the element and the other half across the bad connection. Such a poor connection would probably asl show signs of having been very hot.