Electrical Splices – Where Should You Splice?

One of the many tough decisions electricians have to make is where and when they can make an ‘electrical splice’. There are some codes in the National Electrical Code book that prohibit splices in certain locations or applications. Ideally, an installation is done with as few splices as possible; in a lot of places, that works out. Because electricians over the generations do their best to avoid too many splices, there have been a lot of myths on this subject. In this article we will discuss the can’s and can’ts of electrical splices.

What is an electrical splice? There is no definition in the National Electrical Code book – however, it brings the term up throughout. In 1964, The New York Times published an article that defines a splice as ‘two or more electrical wires joined together’; the joint formed is called a splice. If we take this definition to be true, then we now need to understand some basic codes. NEC Article 110.14, Electrical Connections, states that “… devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be properly installed and used”. 110.14(B) states that “Conductors shall be spliced or joined with splicing devices identified for the use or by brazing, welding, or soldering with a fusible metal or alloy. Soldered splices shall first be spliced or joined so as to be mechanically and electrically secure without solder and then be soldered”. All electrical splices need to be identified for the conductor’s material in that connection. Connections need to be made with identified means for the purpose. Today, electricians use a lot of terminal blocks, as well as wire connectors known as ‘wire nuts’.

One of the major downfalls from making too many splices in an electrical circuit is that there is room for error. There is a phrase: loose wires start fires. This is true. The dreaded job of troubleshooting an electrical circuit when it’s not working properly can be daunting – especially if there are splices that the electrician doing the troubleshooting doesn’t know about. Because of this, a lot of foreman electricians will use the code to scare their apprentices away from making splices. 

There is a big myth that it’s a code violation to make a splice in a panel; we will cover that a little later. For now, we will address some genuine code violations with splices. 

Article 300.15, Boxes, Conduit Bodies, or Fittings – Where Required, says: “Where the wiring method is conduit, tubing, Type AC cable, Type MC cable, Type MI cable, nonmetallic-sheathed cable, or other cables, a box or conduit body shall be installed at each conductor splice point, outlet point, switch point, junction point, termination point, or pull point”. This is telling us that we have to have a box at all splice points. Splices made behind sheetrock or up in the attic of a home without boxes are violations of this code. 300.15(H), Insulated Devices, refers to 334.40. Both state that it is not a violation to have a splice in one of those locations, when nonmetallic cable is spliced with a listed insulated device. This is known as an ‘in-wall splice kit’. Electricians seem to struggle with the concept of the in-wall splice kit because these are new in the code book, and up until 2014 they weren’t allowed.

There are other places within an electrical circuit that electricians don’t seem to like having electrical splices. The electrical cabinet, or panel, is one of those places. For some unknown reason, splices in panels seem to be frowned upon. While reading a post on a fellow electrician’s social media, he mentioned that for 30 years he had been teaching his employees that it’s a violation to make a splice in a panel. He said that his father had taught him that it was a code violation and that he’d never checked the code book for himself. This is not an uncommon thing in the electrical world. A lot of times electricians don’t take the time to actually look in the code book, or they have a personal opinion about a certain method or practice. Oftentimes they teach apprentices that certain methods or practices are code violations, when that’s not always the case. 

312.8(A)(2) is the code article that covers splices in an electrical panel. It says that the area of all conductors, splices and taps installed at any cross-section cannot exceed 75 percent of the cross-sectional area of the space. This seems like it would be an easy code to violate, but there would have to be a lot of wire nuts to accomplish that. There are some electrical installations that would require you to have splices within an electrical panel, such as a shunt trip breaker in a commercial or industrial based project. The shunt trip type breaker is manufactured with two wires built into the breaker that the electrician has to splice to. These breakers are obviously installed in electrical panels, so it would be quite difficult to avoid making a splice in this application.

Like a splice in an electrical panel, making a splice underground without an enclosure or box is frowned upon. I personally see why electricians would have a hard time with making a splice in these locations. Besides, we’ve already mentioned in-wall splices.

Splices should be installed in an accessible location. ‘Accessible’ is defined in the National Electrical Code book as capable of being reached for operation, renewal, and inspection. Code articles 300.15(G) and 300.5(E) state that direct-buried conductors or cables can be spliced or tapped underground without a splice box, if made in accordance with 110.14(B), which is titled Splices. It tells us that conductors being spliced ‘shall be with devices identified for the use’. Using a listed device makes perfectly good sense – however, putting a splice underground with no enclosure could make it hard to troubleshoot if the connection were to come loose. The same goes for an in-wall splice kit. Both a listed in-wall splice and a listed direct-buried device should be thoroughly inspected and tested before they are covered. This of course is my opinion. Know that the whole purpose of the National Electrical Code is to be a practical safeguarding of persons and property, as stated in 90.1(A). If the code gives an allowance like it does for in-wall splices or listed direct-burial devices, then it’s safe if done correctly. 

The final installation for electrical splices that will be disguised is within conduit bodies. 314.16(C)(2) covers conduit bodies with splices. This is pretty basic, and there is not a lot to it. 314.16(C)(2) says that splices can be made in a conduit body if it is manufactured with a legible marking of its volume. Most electricians I have worked with are unfamiliar with this code, as well as how to size conduit bodies. I personally don’t run into too many splices in conduit bodies, but I know they’re out there. I have heard from a couple former foremen of mine from when I was an apprentice that it’s against code to make a splice in a conduit body. Again, there are a ton of electrical myths out there about electrical splices. Knowing when and where a splice can be made without creating a code violation or safety hazard is very important in all installations. Knowledge is power. You can save money if you know what is allowed, or you can go the extra mile to ensure that your installation is more safe. The code is a minimum standard of how you should do your work, and it’s always changing. 

Be safe out there, and make sure to keep yourself educated to be the best electrician that you can be.

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