Twist-On Wire Connectors: 6 Common Mistakes & How to Avoid Them

Think you could twist on a wire connector with your eyes closed?  You might want to at least open your right eye.  Think all wire connectors are created equal?  Think again my friend.  In this article we will discuss six common mistakes that Electricians make every day when using twist-on wire connectors, and how these errors can be avoided. 

Mistake #1: Wrong connector size.


Just because wires will fit into a connector, doesn’t make it right.  Often times Electricians will get into a habit of using a particular twist-on connector, and begin to think that connector is the correct fit for all typical splices.  But not all contractors know that only certain wire combinations have been approved by UL for each individual connector.  Not using the proper size can lead to failed connections, unsuccessful inspections, and unnecessary do-overs.

It is important that every Electrician understand which wire connectors can fit which wires per UL specifications.  Most twist-on wire connector manufacturers will provide this information on their websites, so it is important to check before every job.  Keep these websites bookmarked on your browser, and make it a habit to check them often.  In the case that this information is not posted online, do not hesitate to contact the manufacturer of the wire connector you are using.  They will have a complete list of UL tested and approved wire combinations, and will be able to provide this information for you.  Remember, not all twist-on connectors are created equal, so it’s important you do your research and make an informed decision of which connector to use for every job.

Mistake #2: Incorrect UL Listing per job specifications.


This one is especially important because, as you know, a connector that does not meet the proper UL requirements cannot pass inspection.  And a job that cannot pass inspection means rework that costs valuable time and money.  Every Electrician knows that the NEC code book is an Electrician’s bible.  But knowing the code won’t do a thing for you if you don’t know which wire connectors may be used to uphold these requirements.  Here are a few quick steps to follow to make sure you’re installation is up to code:

  1. Know the Code – Electricians often think they know the NEC Code, but leave out important details that cannot be overlooked.  Make sure you are up to speed when it comes to things like wet and damp job locations.  A different connector is required for these instances, and it is important you get it right the first time.
  2. Know what connectors are on the market – Just knowing the code is a start, but knowing what twist-on wire connectors are available is a big help.  Several Electricians find that the best way to do this is maintaining an open relationship with your distributor.  They are usually the first to know when a new connector comes out on the market, so make sure you are in constant contact with them to make sure you are always getting the best item available for a specific job.
  3. Know how to use them – Installing per UL requirements is just as important as choosing the right connector, so make sure that you skim the installation instructions before installing any wire connector no matter how simple the twist-on connector may seem. 

Mistake #3: Improper strip length.


This should be an easy one, but inspectors are still finding over-stripped wires on job sites every day.  We have gotten too comfortable.  Several electricians will “eyeball” the strip length, and many are successful.  But oftentimes this haste only leads to exposed wire. 

Measuring each wire is a foolproof way to avoid over-stripping, but innovations in the industry have made it a bit easier on busy Electricians.  Several wire strippers today have measuring tools built right in, so you can set the appropriate strip length and, as long as you are using the same connector, strip wires all day without a problem.  In the case that you do slip up, manufacturers also offer a variety of twist- on wire connectors with a plastic skirt on the end to help protect exposed wire.  Keep in mind though, that these skirts are to be used just in case of over-stripping; they are not an excuse for sloppiness!  It is understandable that taking these precautions can be time consuming, but I like to remind Electricians that measuring each wire does not take nearly as much time as going back to a job site to repair a failure.

Mistake #4: Too much or too little torque.


The danger of too little torque on a connector is not something that can be ignored.  A loose connection will lead to arcing, which can cause poor conductivity, overheating, and can even be a fire hazard!  It only takes one weak connection for an entire system to perform poorly, so it is crucial that you take your time to tighten down each individual wire connector.  Conversely, a connection that is too tight can cause damage to connectors or to the wires themselves.

Here’s a quick checklist you can use to make sure your wire connector is torqued down tightly.  Ask yourself, does the connector feel tight?  Are the wires that are outside the connector twisted around themselves?  Can you pull the connector off without twisting?  If you answered yes to the first two questions and no to the last, odds are you have a solid connection.  It is up to each Electrician whether he or she chooses to use a tool to tighten down wire connectors.  Whatever method you choose, keep it as tight as possible without damaging the wires. 

Mistake #5: Wrong connector voltage.


We cannot stress this enough…read the fine print.  An Electrician I know (we will call him Bob, so as to keep his identity anonymous) was doing a landscape lighting installation for a homeowner.  He chose to use some low voltage waterproof connectors that he had on hand to complete the installation.  Typically, this would have worked just fine; however, the light fixtures Bob was installing called for a wire connector that was UL approved for up to 600V.  Not only was Bob forced to spend the time re-doing the connections, but he also lost money on inventory he used and then threw away.  Don’t make Bob’s mistake; do your homework ahead of time!

Mistake #6: Not lining up conductors properly before inserting into connector.


As small of an issue as it sounds, this happens more than you think.  Have you ever been on a job site, it’s Friday afternoon, and all you can think of is making it to your son’s T-Ball game on time?  Hustling through connections like this leads to improperly lining up wire connectors, and can result in failed connections.  As we well know, one hundred well done connections won’t be what the customer remembers…it will be the one failed connection.  Take your time!  It will be worth it in the long run.

Falling victim to one or many of these common errors can leave you with poor connections, unsafe conditions, or failed inspections.  I’m sure we don’t have to tell you that this can lead to lost time, lost money, and more headaches.  If you took away anything from this article, let it be this: take your time, do your homework before you start a job, and get it done right…the first time.

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