The age old debate: Are double tapped neutrals a problem?

Double tapped neutrals: what exactly does this mean? Neutral wires are the white wires in an electric panel, and are an integral part of a home’s electrical system. They are designed to complete an electrical circuit, as their purpose is to return current to the electric panel. The term “double tapped neutrals” refers to when more than one neutral wire is set under a single lug on the neutral bus bar in the electric panel. This was a common practice by electricians’ for many years up until 2002, when the National Electric Code (NEC) specifically stated that neutral wires must be isolated individually under their own lug on the bus bar. The fact of the matter is, double tapped neutrals have never been allowed, but there was some gray area in the NEC, which mislead electricians’ to misinterpret the code and double tap neutrals.

Double tapped neutrals can be both a minor issue, as well as a major issue. When wires are double tapped, they can come loose because neither one of the wires has a good connection or can be properly torqued to be secure. When a loose connection occurs, arcing can result, which can represent a fire hazard. Double tapped hot wires (black or red wires) have never been allowed in the NEC (there is an exception to this, as some circuit breakers are rated for double taps). So why did electricians’ think that double tapped neutrals were ok? Neutrals are current carrying conductors, and can just as easily come loose as hot conductors. Before 2002 when the NEC spelled out specifically that double tapped neutrals were no longer allowed, there was nothing stating that double tapped neutrals were not allowed in the NEC. What was stated is that electric panels must be installed according to UL 67, which is the safety standards set forth for panel boards. UL 67 has been around for a long time, and has never allowed neutrals to be double tapped. Since it was not specifically stated in the NEC, electricians’ did not seem to think anything was wrong with double tapping neutrals.

Now, when two neutral wires are set under a single lug, if they are both the same wire size (both 14 awg, both 12 awg, etc), and there are ONLY two of them under a single lug, then they are likely to have a good connection and never present an issue, even while technically not being allowed. When more than two are set under a single lug (which is almost always the case), then problems can arise. There is no way that lug can be properly torqued with all those wires bundled underneath it, and all those wires have a solid connections. It’s not happening, and don’t let an electrician tell you it is. Another issue is when two neutrals are under the same lug, but they are different wire sizes (a 14 awg and a 10 awg, for example). Those two different wire sizes also present a torquing issue, where one will not have a good connection.

Any panel installed after 2002, it is a no brainer that double tapped neutrals are not allowed, with concrete evidence of this in the NEC, but it is still common to see them double tapped. Why is this? Unfortunately, many people have the belief that if it wasn’t a problem before, then why would it be a problem now? That way of thinking is like saying “I haven’t gotten lung cancer from smoking yet, so I don’t see why I would ever get it, I’ve been smoking for 30 years!” Many electricians’ will argue this point regarding double tapped neutrals relentlessly, but the proof is in the pudding, and according to UL 67, it has never been allowed. And it has never been allowed in the NEC either, but it wasn’t written out that way specifically until 2002.

As mentioned above, double tapped neutrals can both represent a minor and a major defect, and just because you have double tapped neutrals does not mean that your house is going to burn down. It just simply means that there is a defect in your panel, and whether or not that defect can lead to repercussions is relatively unpredictable. Isolating neutrals is an easy task, can be done inexpensively, and in a short amount of time. It is also one of the most common defects found on almost every home built prior to 2002, and makes it into almost every inspection report as well. It should not be a deal breaker, but it should be addressed eventually.