Double Tapped Breakers Explained
Double tapped breakers are one of the most common electrical defects found in the homes we inspect here in Richmond. Although it is a home inspection defect, and it is a potential fire hazard, I don’t consider it to be a major defect and it is generally easy to fix.
What is Double Tapping?
The most accurate description is that a double tapped breaker is when two hot wires (the black wires) connect to the terminal of one breaker that is listed for one wire. The problem is that it can cause loose connections, arcing, and potentially an electrical fire. You can see an example the photo below. The blue tape was applied so can you visualize it better.
Is Double Tapping a Code Violation?
The national electrical code (NEC) does not have a code specifically stating that double tapping is prohibited. The applicable code is 110.3(B) which states;
“Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling”
In other words, the NEC states that the breaker must be installed in accordance with how the manufacturer requires it to be installed. As stated, most manufacturers only allow one wire to be installed in the breaker terminal.
It is absolutely a code violation to double tap a breaker.
How to Repair/Correct Double Taps
make sure its an actual defect. Some manufacturers make breakers that are listed and approved to hold two conductors. In the photo below, you see the plate has two grooves, and it is listed and approved to have two wires. Some home inspectors write them up anyway, but I
believe KNOW they are wrong for doing so.
After removing the panel cover, you can examine the front of the breaker for a label or diagram that states two wires can be installed. Both electrical wires need to be the same size and same material. You can not install a copper wire and an aluminum wire in the same terminal. You also can not install a size 14 wire and size 12 wire in the same terminal.
Sometimes, the label or diagram is on the side of the breaker and you will need to remove the breaker to examine it.
A common mistake I see home inspectors is confuse the number of poles, with the number of wires allowed. A single pole breaker does not mean it is only listed for one wire.
To be clear, if the breaker is listed for two wires, and it has two wires installed, it is not a double tap. It is only a double tap when two wires are installed on a breaker that is only listed for one wire.
The only manufacturers I am aware of that make these breakers are Cutler Hammer, and Square D.
there is no need to freak out. This is generally an easy fix. A licensed electrician can usually just pull the two wires out, pigtail them to a third wire with a wire nut, and connect the third wire by itself to the breaker. Now there is only a single conductor connected to a single circuit breaker.
Even though this is one of the most common ways to correct the issue, it is not always acceptable. There may be two many devices on the circuit, or one of the circuits may be a required dedicated circuit.
An electrician can also install a new breaker in the main panel, or add a tandem circuit breaker (shown below) if the panel allows tandem breakers to be installed. Tandem breakers are basically two smaller breakers that take up the space of a single breaker. Not all panels allow the installation of tandem breakers, and some panels limit the spaces where tandem breakers can be used. This is also not that expensive.
Unfortunately, if there is no extra space in the main electrical panel, and the panel does not accept tandem breakers, then it might not be a simple repair. This is more common an older electrical system, and at this point, it may be a better long-term solution to have an electrical contractor replace the breaker box with a larger one.
If you feel confident, you may even be able to do the work yourself. We always advise having qualified tradesman perform repairs though.
Double tapping doesn’t just happen at the breakers. It can also occur on the neutral bar although the proper term for this is double lugging.
Double lugging is when two grounded conductors, also called neutrals, or the white wires, are under one screw/terminal. This is a defect because each terminal in the neutral bus bar is only listed for one grounded conductor. One problem, which you can see on the right is that the connections can become loose, which can cause arcing.
Another problem is that loosening the grounded conductor of an MWBC in the panel can be a safety hazard if its under load because the current will flow to, and possibly over load one of the circuits in the MWBC.
Ground wires a different
The last thing to consider in regards to double tapping is that you generally are allowed to have at least 2 ground wires in one terminal. A ground wire is usually a bare copper wire. The label will list how many ground wires can be installed in a terminal. Remember to always install everything in accordance with its label and listing.
I’ve outlined a pretty full answer here. The short of it is that double taps are a common defect, but are easy for any qualified electrician to repair, and should not be something to worry about.