Reuben's Home Inspection Blog

Double Tapped Neutrals: This Isn’t A New Rule

May 24th, 2011 | 8 comments

Double Tapped NeutralThe problem I’m addressing today is double tapped neutral lugs in electric panels.  A ‘double tapped neutral’ is a slang term for saying that one of the screws on the neutral bus bar in the panelboard has more than one neutral wire feeding to it.  This is a no-no, and has been for a long time.

One reason that two neutral wires can’t be connected to a single terminal in a panelboard is so that the circuit can be isolated if it needs to be worked on.  There is a great explanation of this at the Schneider-Electric web site.

The other reason two neutral wires can’t be connected under a single lug is because the connections might come loose, which could lead to a fire.  The images below show an overheated conductor at a double-tapped neutral lug.  The left image shows the original photo, and the right image has a thermographic overlay from an infrared camera.

Overheated Neutral

While panel manufacturers will allow for up to three grounding conductors under a single lug, they typically only allow one neutral wire.  The grounding conductors aren’t going to normally carry current for extended periods of time, so they have a very slim possibility of coming loose.  This isn’t the case with the neutral conductors.

Despite what many seem to think, this didn’t become a new requirement in 2002.  This has been a requirement of UL 67 for a long time, but was spelled out in the NEC in 2002.

Reuben Saltzman, Structure Tech Home Inspections - Email - Minneapolis Home Inspector

        

 

8 responses to “Double Tapped Neutrals: This Isn’t A New Rule”

  1. Melinda
    May 24, 2011, 8:42 am

    Not that this has anything to do with your blog, but there is an article on the MSN about the importance of hiring a home inspector when you purchase a home. Made me very grateful that we hired you. Although you didn’t find any major stuff, it was just nice to know what we were walking into and what would have to be fixed down the road. It was totally worth the money.

  2. James
    May 24, 2011, 12:14 pm

    Isn’t double tapped hot into the circuit breaker a no-no too?

  3. Reuben Saltzman
    May 24, 2011, 3:45 pm

    Melinda – thanks, much appreciated!

    James – yes, it’s usually a no-no on circuit breakers too. I wrote a blog about that here http://www.structuretech1.com/2010/01/how-to-correct-double-tapped-circuit-breakers/

  4. Woody
    June 15, 2011, 6:07 am

    1) Since you cannot work on that panel ‘live’ the isolation arguement is moot.
    2) UL 67 does not apply since those are not neutrals. They are grounded conductors.
    3) That makes it a code violation. A safety hazard? Very,very,very remote possiblitity.

  5. Reuben Saltzman
    June 16, 2011, 4:23 am

    Hi there, Mike. You’re going by “Woody” now? I’d say it’s good to hear from you… but, well, you know.

    1) Since you cannot work on that panel ‘live’ the isolation arguement is moot.

    I’ve heard this tired old argument from you before. In the real world, electricians work on live panels all the time.

    2) UL 67 does not apply since those are not neutrals. They are grounded conductors.

    I’m sure you’re already aware of the change in the 2008 NEC to define the term neutral conductor. http://www.iaei.org/magazine/2006/07/analysis-of-changes-part-1-nec-2008/ . You can’t seriously believe that UL 67 doesn’t apply to neutral conductors.

    3) That makes it a code violation. A safety hazard? Very,very,very remote possiblitity.

    Well, I guess I should be glad that’s you’ll admit it’s a possibility. I have to assume you’re digging your heels in on this one because of that blog post you wrote on ActiveRain about two years ago, and long discussion that followed it. http://activerain.com/blogsview/1225687/bad-home-inspection-info-electrical . Yes, yes, I know that most of that discussion was about grounded and grounding conductors being connected under the same terminal, but I also called you arrogant and said you have a chip on your shoulder. I don’t think anything has changed.

  6. Photos From New Construction Inspections | Structure Tech Home Inspections
    November 10, 2011, 5:20 am

    [...] but I do find them.  In the next two photos below, there are double tapped circuit breakers and double tapped neutral wires.  These breakers aren’t designed to be double tapped, and neutral wires are never allowed to [...]

  7. Photos from New Construction Home Inspections, Part II | Structure Tech Home Inspections
    November 5, 2012, 11:07 am

    [...] I don’t find a lot of electrical defects on new construction homes.  This is the one trade where the installations are almost always very clean… almost.    In the photo below, there are two neutral conductors connected to a single terminal.  Each neutral conductor needs to be connected to its own terminal. [...]

  8. Home Inspections and Infrared Cameras | Structure Tech Home Inspections
    September 17, 2013, 4:51 am

    […] Scanning electric panels with an infrared camera can easily identify overheated conductors or circuit breakers.  The panel shown below had an overheated neutral wire, which I suspect was the result of a loose connection; there were two neutrals connected to a single lug. […]

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