Why is bundled wiring in an electric panel a defect?

Tuesday, July 10, 2018

Neat and organized wiring is one of the ways you can tell that an electric panel was wired by a professional electrician. Wires from breakers on the right side of the panel exit the box on the same side. They don’t cross over the service cables or run around the bottom. This requires planning and careful execution, and the completed work sometimes resembles a wiring diagram, with each wire turning at a right angle next to the breaker before it heads up or down and out of the box.

     A good electrician is justifiably proud of a well-organized panel. But bundling the wires together with zip-ties to further enhance the organization of the panel, like in the photo above, is a step too far. Both the wiring and breakers in a panel generate heat and air space around the components is needed for heat dissipation. When the wires are bundled, heat generated by the inner wires is trapped by the surrounding ones. Also, each wire connected to a breaker helps to conduct heat away from the breaker, but this is nullified if the wire runs into a bundle just an inch away from the circuit breaker terminal.

    The National Electric Code does not directly ban bundling in a panel but does require adjusting wire size (derating) for bundled wiring 24-inches or more in length as a way to avoid overheating. Because many wires converge and heat is concentrated in an electric panel, even if the length does not exceed 24-inches, bundling is still the wrong thing to do. 

    Also, see our blog post Why do some wires in an electric panel have tape wrapped around them near their connections?

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

Which house appliances need a dedicated electrical circuit?

Can a short circuit cause a high electric bill?

What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

What causes copper wires to turn green or black in an electric panel?  

What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

Why is it unsafe to bond neutral and ground wiring at subpanels?

Should I get a lightning rod system to protect my house?

Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

Does a wire nut connection need to be wrapped with electrical tape?

What is the minimum clearance of overhead electric service drop wires above a house roof?

What are the requirements for NM-cables entering an electric panel box?

What is the color code for NM cable (Romex®) sheathing?

Why is undersize electric wiring in a house dangerous? 

What causes flickering or blinking lights in a house?

Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

How can I find out the size of the electric service to a house?

What could cause an extremely high electric bill?

Can old electrical wiring go bad inside a wall? 

What is an open electrical splice?

What are the most common electrical defects found in a home inspection? 

What is the life expectancy of electrical wiring in a house? 

What is an "open junction box"? 

How dangerous is old electrical wiring? 

What is a ground wire? 

I heard that aluminum wiring is bad. How do you check for aluminum wiring? 

What is "knob and tube" wiring? 

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles. 

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