As a homeowner, it’s a matter of time before you’ll need to learn some basic electrical skills as part of your home improvement projects. You might need to splice wires to extend a wire, repair damage, or connect one electrical wire to another.
Splicing wire is a technique for joining two pieces of wire together to carry an electrical current. You do this for many projects, like relocating light switches or outlets and making repairs.
Read on as we cover the ins and outs of how to splice electrical wires safely for your DIY projects.
Whether it’s your first wiring project or your 100th, safety is critical. Be sure to follow the tips below to ensure you’re staying safe.
Always disconnect power to the circuit at the service panel before you begin working. Ensure the power is off using a non-contact voltage tester on the hot wires and ground wires before you get started.
When you splice wire, always make sure you’re using the same gauge. When splicing wires of different gauges, the lower gauge wiring can handle more amperage than the higher gauge wire. As the current travels through the splice, it can overheat and create a fire risk.
When splicing wires, always use a junction box to place all the spliced wires. Junction boxes protect from electrocution and fires by containing any sparks that occur during a short circuit. Attach the junction box to a wall stud or ceiling joist in a spot that won’t place undue stress on the wiring.
Be sure to finish all your connections with a shrink tube or a twist-on connector. Never use electrical tape to shield your connections.
How to Splice Electrical Wires
Follow this step-by-step guide, and you’ll be well on your way to splicing wires like a seasoned professional.
Be sure to cut off power to the wires you’re splicing. Never splice wires if you’re unable to cut off the power.
If you’re splicing insulated wires, use a wire stripper to remove about five inches of the outer sheathing from the wire. Then, remove about ½” of the plastic sheathing from the individual copper wires.
Examine the wiring for signs of damage. Look for burnt wire insulation, cut wires, nicks, or bite marks. Remove any damaged areas before you begin splicing.
Slide a piece of shrink tubing over the wire you’re splicing as you’ll need it once you complete the splice. You can skip this step if you’re using a wire cap to attach the wires.
If you haven’t set up your junction box yet, use your needle-nose pliers to attach clamps into the openings on the opposite ends of the box.
Making a Lineman’s Splice
Electricians started using the lineman’s splice, or Western Union splice, in the early 1900s. It’s ideal for joining two wires that will be kept under tension. Here’s how:
- Hold the wires parallel to one another. Bend the top wire down and over the bottom wire, and vice versa.
- Wrap each wire around the other wire several times until you run out of wire.
- Solder the connection to provide additional protection and conductivity.
Using a Twist-On Connector
A twist-on connector is an alternative to the lineman’s splice. Here’s what you’ll need to do to complete this splice.
- Hold both pieces of wire even with each other.
- Place both ends into the twist-on connector.
- Twist the connector to lock the two wires into place.
- Tug at each wire to make sure that the connection is strong.
When working with these devices, only use UL-listed products. Ensure that the connector covers all the exposed wiring you’ve stripped back. If you can see exposed wiring, you’ve stripped off too much. Trim your twisted wires and reconnect.
After making your connections, place them in the junction box and put the protective cover on. Then, secure it with screws.
When to Call an Electrician
While handling minor electrical repairs and modifications yourself is possible, the work can be dangerous if you’re not careful. If you’re feeling uneasy about doing electrical work yourself, call in a professional electrician.
With over 30 years of experience, our team at U.S. Electric can get your job done safely and efficiently. This way, you can enjoy your home or business to the fullest. Contact us today to discuss options with a professional electrician!
Twisting the wires together and soldering is often the best method, but there are two ways of doing this. If possible, you should twist the wires in-line before soldering as this makes a stronger (and neater) join than twisting the ends together.Is it against code to splice wires? ›
A splice is a connection between two or more wires and is one of the worst code violations. The splice is illegal and dangerous if not contained inside a junction box. The only times splices like this can legally occur are for temporary lighting and circuit troubleshooting.What is the first thing that you need to consider in splicing a wire? ›
Before you splice wires together, disconnect any power going to the wires and strip back 1 inch of each wire's insulation. Then, hold the wire ends so they're touching one another and twist a wire cap clockwise onto the exposed wires, which will wrap the wires together inside of the cap.Can a spliced wire cause a fire? ›
Leaving an Open Splice or Unprotected Wiring
This is a huge fire hazard, especially if the splice is within sparking distance of flammable material. If you're splicing wire as a step to create connections for new areas of your home in need of electricity, make sure to cover it after the connection is made.
Does that mean you have to rewire the entire circuit? Fortunately, no. Savvy electricians can splice wires together, safely adding the length they need to reach their destination.Can I connect two wires without a junction box? ›
Short answer: NO. Long answer: All splices must be in a junction box, and the junction box must be accessible.What are the different methods of joining wires? ›
- 1: Crimp Splice. The In-Line Crimp Splice is simple and requires minimal tools. ...
- 2: Solder Sleeve. ...
- 3: Terminal Block. ...
- 4: Ultrasonic Weld. ...
- 5: Solder.
Never use tape in place of wire nuts—it's simply not secure enough, and it's vulnerable to damage. Some people like to use wire nuts and wrap them with tape. This fine to do, but you probably won't find any wire nut manufacturers advising you to do it.Do all splices need a junction box? ›
Electrical splices can never be left on their own in a wall or ceiling cavity. Instead, all splices must be contained within an approved junction box or fixture electrical box.Is it OK to splice Romex? ›
It must be noted that while it is possible to splice different types of Romex wire—12/2 to 12/3, for instance—you should never splice together wires of a different gauge. Wire gauge is determined by the amount of amperage the wire is expected to carry.
For safety considerations, always turn the power off in the circuit when performing cable splicing. You can safely splice three or more wires as long as you follow basic instructions.How do you prepare the wires before splicing them together? ›
Prepare the wire by stripping the wires ends using a wire stripper. If you are working with stranded wire, try twisting the ends to group the strands together and tinning the tips before soldering. Cut a piece of heat shrink to cover the exposed wires.What is the most common method of terminating and splicing wires? ›
Crimping. Crimping is the most commonly used method of wire termination, and is most efficient for high-volume wire termination. The terminations are fast, clean and mechanically strong.How many times can you splice an electrical wire? ›
There is no limit to the number of boxes or splices, only a length limit. In the specifications of most of the commercial and industrial jobs we wire they require an increase in branch circuit wire size if we exceed 100 feet. This is a "rule of thumb" without doing a voltage drop calculation.What is a floating splice? ›
The term “flying splices” is an electrical term for wiring that has been spliced together, meaning that the wires have been connected, left open and not enclosed in a junction box.Are splicing connectors safe? ›
Be on the Lookout for Improperly Spliced Wires
If the connecting wires become overloaded or loose, they can overheat and cause sparks. If you allow these wires to stay in the open, then those sparks could cause a fire.
- Understanding the Fire Code. ...
- Check Your Fuse Box. ...
- Organize Wirings. ...
- Choose Safe and Quality Appliances. ...
- Child-proofing Electrical Outlets. ...
- Responsible Use of Extension Cords. ...
- Repair Loose Plugs. ...
- Always Consult an Electrician.
What you need: a roll of electrical tape and two wires whose ends have been twisted together. First, lay the twisted part of the wires onto a strip of electrical tape. Wrap the tape around the wires tightly 5-6 times, making sure to cover up all the wire. Give your connection a tug to make sure it is strong.Is it OK to cut wires with scissors? ›
Scissors, clippers, and the like just aren't made to cut wire. Chances are you'll end up with dull scissors or clippers from trying to cut the wire, or worse—you'll completely damage or ruin the tool. These aren't sharp enough to cleanly cut wire, so the wire will end up being bent out of shape.What happens if you tie a neutral and ground together in a junction box? ›
No, the neutral and ground should never be wired together. This is wrong, and potentially dangerous. When you plug in something in the outlet, the neutral will be live, as it closes the circuit. If the ground is wired to the neutral, the ground of the applicance will also be live.
Junction boxes are an integral part of virtually every electrical installation.Do electrical connections have to be in a box? ›
Electrical codes generally require that all electrical devices, and the wiring connections to those devices, must be enclosed in an approved electrical box. 1 Often known as a junction box, this metal or plastic box includes a cover to protect the wiring within and protect you from the wiring.Which wire splice method is the most reliable method? ›
Soldering is the most common method for wire splicing in custom cable production, and it is the most reliable.How do you connect electrical wires safely? ›
Twist the electrical wires together tightly starting at or near the first bit of exposed wire. Always twist the wires in a clockwise direction. That way when you screw on a twist-on connector (which also is tightened by turning it clockwise) you won't be un-twisting your wires.What are the 4 types of electrical splices and joints? ›
There are four main types of splice joints: half lap, bevel lap, tabled, and tapered finger.Is it OK to use electrical tape instead of wire nuts? ›
Yes, but first you must twist the wires securely with linemen's pliers, then wrap the twisted wires with rubber tape and then electrical tape. This is how it was done before wire nuts.What can I use if I don't have electrical tape? ›
- Duct Tape. You've guessed it right! ...
- Wire Connectors. Wire connectors are a great alternative to electrical tape for a number of reasons. ...
- Heat Shrink Tubing. ...
- Friction Tape. ...
- Dielectric Spray. ...
- Rubber. ...
- Vinyl. ...
Longitudinal steel lap splice is always required in reinforced concrete (RC) columns. Normally, in countries having high seismic risk, lap splices of longitudinal steel must be located around mid-height of the storey.Is a splice stronger than a knot? ›
A Splice is usually significantly stronger than a knot and is intended to be permanent. Undoing a splice and re-making it takes much more time than doing the same with most knots.Why is Romex not allowed in conduit? ›
one reason you don't put romex in conduit is because it creates more heat and is not advised in conduit if you have conduit you can run insulated wires instead it's probably cheaper. when you put romex inside conduit The Romex cannot breathe and retains too much heat.
It is not permissible to secure more than one 3-conductor cable under a single staple. Use stacker-type fasteners to secure multiple cables to the same framing member. These allow the cables to be stacked for a neater, safer installation.How many wires can you splice in a junction box? ›
How many wires can a 4-inch junction box hold? In general, a junction box that is 4-by-4 inches with a 2 1/8-inch depth can handle up to six cables.What Splice is the most frequently used? ›
Fusion splicing is the most widely used method of splicing as it provides for the lowest insertion loss and virtually no back reflection. Fusion splicing provides the most reliable joint between two fibers.What is an acceptable splice loss? ›
When it comes to mating of two splices on connectors, the acceptable fiber splicing loss is calculated to be around 0.7 to 1.5 dB per connector. In fusion splicing, the acceptable loss is reduced to around 0.1 to 0.5 dB per splice.What are the requirements of splices? ›
In order to get the maximum splicing efficiency the fiber should satisfy following criteria: a) They should be perfectly aligned. b) They should have the same geometric characteristics i.e. same core diameter. c) They should have same optical characteristics i.e. ∆, NA should be same.What are the two steps of splicing? ›
- In the first step, the pre-mRNA is cut at the 5' splice site (the junction of the 5' exon and the intron). ...
- In the second step, the 3' splice site is cut, and the two exons are joined together, and the intron is released.
One of the primary root causes for splicing failures is poor cleaning of aluminum strands prior to compression. The Electric Power Research Institute has developed technology that enables line crews to properly prepare conductors quickly, efficiently and affordably.What is the best tools to use when splicing wires? ›
Splice kits can include many different tools to ensure a safe joint between cables. These tools include a wire cutter, needle nose pliers, wire strippers, and electrical tape. Wire cutters, also called diagonal cutters, are intended for cutting wire instead of grabbing or turning anything.What are the 2 types of cable splicing? ›
Types of Splicing
There are 2 methods of splicing, mechanical or fusion. Both methods provide much lower insertion loss compared to fiber connectors.
Per the 2018 International Residential Code, electrical wires should be set back no less than 1-1/4 inches from the edge of the framing lumber. Limiting drilling depth to less than 1-1/4 inches is a good start to reducing the risk of damaging wiring behind the drywall.
Electrical splices can never be left on their own in a wall or ceiling cavity. Instead, all splices must be contained within an approved junction box or fixture electrical box.What happens if you hit a live wire while drilling? ›
If you suspect that an electric cable has been hit, it is absolutely necessary to repair it. You should immediately ensure that the power is switched off before touching anything. In the worst case, if the protective earth conductor has been damaged you otherwise run the risk of a fatal electric shock.Do stud finders detect wires? ›
The stud finder wall scanner can quickly find the edges and center of metal studs, pipes, rebar, joists behind walls, floors, and ceilings as well as the live AC wires.