Originally Posted By: Dennis Bozek
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Joe,
My answer would be no because a neutral is a current carrying conductor where a ground is not. Also the neutral bus bar is not rated for double lugging. Typically the largest gauge wire you can put into a neutral buss is 4 gauge and it fits quite tightly. Regardless of that fact though, I do not ever double lug any wires other than a ground and a ground purely because grounds are not current carrying conductors. Double tapping and lugging can create hot spots on breakers and neutral bars if not tightened to the correct torque and especially if two different size conductors are used. This is especially true if aluminum conductors are used and they are not protected against corrosion with De-ox. Because the hot and neutral wires are current carrying conductors, the chance is then greater for potential hot spots. If the double tap or lug becomes lose, it begins to arc. As it arcs it builds up carbon. Carbon is then resistance and with the more carbon buildup the more difficult it is for the conductor to make contact....thus increasing the current. End result can be the breaker tripping because of the loose conection (excessive current exceeding the rating of the breaker), or signs of overheating such as discolored wires, melted wires, etc, or worse yet...fire! I have often double lugged ground wires and have yet to fail a EI inspection for it. You will never see a panel done by me though that has double tapped hots or double lugged neutrals. I just won't do it....to me it is a safety issue.
I carry a temperature sensor, which is a battery operated laser that can measure temperatures up to 2000 degrees Farenheit. I use this device when inspecting and/or troubleshooting electrical panels. One can measure the temperature at the point of connection in the breaker and at the neutral buss. These temepratures should be relatively close to one another. Some might be a tad higher than the rest due to different types of loads causing more current thus creating more heat (power). I think if a panel that utilizes breakers rated for double taps is questionable, this would be an excellent way to determine if the connection is safe or not. But again as I mentioned in my previous post...I always put a single wire on a single connection.
Another example of what loose connections can do is sometimes seen in a wirenut, that does not have all the wires properly "tied" within the wirenut. What typically happens is the connection made by the wirenut becomes hot, thus causing either a loose or intermittent connection. In this example, as the wires try to make contact, they buildup excessive current doing so and promptly will melt the wirenut. The next time I see a melted wirenut or melted wires at a breaker due to double tapping, I will post the pics on this BB. So my point is....double tapping might be acceptable for some breakers rated for such....but it is not a good rule to follow. Double lugging anything other than 2 ground wires is never an acceptable practice by me.
Sorry for the long response Joe but sometimes I am long winded....just ask Russ lol.
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This information has been edited and reviewed for errors by your favorite resident sparky.