I was talking with an electrician friend of mine at a gathering this Christmas and we talked about one of the most commonly called out defects, double tapped circuit breakers, during an home inspection. While it means "business" for him he was saying how some home inspectors don't know exactly what they are noting and cause undo concerns when everything is actually OK. He quizzed me. I passed.
I am not an attorney and didn't seek the super-duper advice before writing this post, so here is my disclaimer before giving any electrical how-to information: Don’t do any of this work if you’re not qualified. Qualified means LICENSED and trained in electrical work. Reading this article, or watching a home improvement show, does not make you qualified. You could be seriously hurt or killed. This is only an informative overview on what I have found.
Definition: There is no official term for this, so "double tap" is the trade slang. Two conductors are connected under one screw or terminal inside a panel. This could be on a circuit breaker or on a neutral bar. I will write about neutral bars another time. Let's just say that a neutral bar is not a drinking establishment for both Cardinal and Cubs fans. They should always be separate, but I digress.
When IS a "double tap" a DEFECT?
This is a defect when the circuit breaker isn’t designed for two conductors. It doesn’t matter if it’s just a simple doorbell transformer wire that’s added on to the circuit breaker that already has a wire on it – the issue isn’t about the load imposed on the circuit, it’s about the physical connection of the wires.
When is "double tapping" NOT a defect?
Double tapping is perfectly fine if the circuit breaker is designed for two conductors. Only circuit breakers designed for two conductors will say so right on the circuit breaker, and the terminal of the circuit breaker will be designed to hold two conductors in place. The only manufacturers that make circuit breakers that are designed to hold two conductors are Square D (QO and HOM Series) and Cutler Hammer (CH Series). Earlier some Square D HOM series breakers were made, but were only rated for ONE conductor. This is a change that has been made over time. The breaker would still say how many conductors it was rated for. Currently General Electric (GE) and Siemens breakers are not rated for double tapping conductors.
Why is "double tapping" a problem?
If the circuit breaker isn’t designed to hold two conductors, the conductors could come loose at some point in the future, even if they feel very tight today. Loose conductors can lead to overheating, arcing, and possibly a fire. This is a particular concern when two conductors that are not of equal size are landed under the screw of a breaker that IS NOT double tap rated.
Now, how can this defect be corrected? Here is where the licensed electrician comes in and should be doing the work.
1. Pig Tail:
The most common repair is a pigtail. The two conductors under the screw of the circuit breaker are disconnected from the circuit breaker and tied together with a new single conductor under a wire connector rated for the number and size of conductors. This wire connector is commonly called a "wire nut". Your electrician will know what to do. I just want to point out that it is a simple repair.
2. New Breaker:
Another remedy would be to replace the circuit breaker with a type that is designed for two conductors, as long as the panel is designed for it. The breaker MUST be the same manufacturer as the panel. DO NOT MIX AND MATCH BRANDS.
Why Does This Happen:
If there are more problems going on besides just a double tap, the remedy might require more investigating and work. I have seen this happen because of some of the following reasons.
Can this be repaired?
As stated before, this article is for education purposes only. Do not attempt to make these repairs or diagnose electrical issues if you are not trained and licensed. If you have questions contact your favorite home inspector or electrician.
Call Jon Bronemann Home Inspections, LLC for your home inspection in Cedar Falls, Waterloo, Parkersburg, Charles City, Manchester, Independence, Waverly, Dike, Hudson, Jesup, Center Point, New Hampton, Oelwein, West Union, Decorah and other areas in the Cedar Valley.
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