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Thread: Double Tap Question

  1. #1
    DIY Junior Member centurion's Avatar
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    Default Double Tap Question

    I understand is it not acceptable and not to code to put multiple neutrals together on one neutral bus lug, unless the manufacturer of the box specifically allows it.
    I am a realtor and see a lot of home inspections. Almost all of the homes around here, Central NJ, that are in the 20 to 30 year age range, have all or most of the neutrals on one lug. Many of these boxes, including my own home, have not been touched since the house was built and still have the approval sticker on them from when they were originally inspected.
    So my question is, has something changed? Was it acceptable practice to do this before? Did the code change, if so when?
    I am just curious to know why I see so many homes with this that were inspected and approved.
    Anybody know? Thanks.

  2. #2

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    Hello, at that time code allowed that. It is no longer code to do that, but you are grandfathered in. Should the panel be changed it wouldn't be allowed. I also, see it, too.

    You are allowed to have more than one wire but, you won't see 15 or 20 altogether. I am thinking that is what you are seeing. Some city could require one wire per lug, but that is something the city would require and not the NEC.

    I might be wrong but a double tap would be a wire connected to a part of the panel directly connected to the power pole with no protection inbetween.
    Last edited by Cookie; 04-10-2012 at 01:38 PM.

  3. #3
    DIY Junior Member centurion's Avatar
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    Quote Originally Posted by Cookie View Post
    Hello, at that time code allowed that. It is no longer code to do that, but you are grandfathered in. Should the panel be changed it wouldn't be allowed. I also, see it, too.

    You are allowed to have more than one wire but, you won't see 15 or 20 altogether. I am thinking that is what you are seeing. Some city could require one wire per lug, but that is something the city would require and not the NEC.

    I might be wrong but a double tap would be a wire connected to a part of the panel directly connected to the power pole with no protection inbetween.
    Thanks. If it is true that this was allowed by code before, does anyone know when it was changed?

  4. #4

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    Other than that of the manufacturer's listing and instructions, I would think, around 2002, perhaps. I might be wrong, but, what matters is the code of today. JW would know.
    Last edited by Cookie; 04-10-2012 at 02:32 PM.

  5. #5
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Cookie View Post
    Other than that of the manufacturer's listing and instructions, I would think, around 2002, perhaps. I might be wrong, but, what matters is the code of today. JW would know.
    And so would Cookie

    Panelboards was moved from 384 to 408 during the 2002 code cycle when 408.21 was included to mandate one neutral for one screw. Prior to 2002 we used the number of conductors outlined on the label in the panel. As long as they were the same size some panels would allow up to five under certain screws.

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    DIY Senior Member Homeownerinburb's Avatar
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    Quote Originally Posted by jwelectric View Post
    to mandate one neutral for one screw.
    Would it not be correct to say that the code now insists on one wire per screw in every application?

    I cannot think of any place in a residential (what I mostly work on) system where I would be permitted to have two wires at one screw, at all.

    That is not to say that I never stuff a grounding wire from a length of NM under the same screw in the buss as another. But I should not.

  7. #7
    DIY Junior Member centurion's Avatar
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    Quote Originally Posted by jwelectric View Post
    And so would Cookie

    Panelboards was moved from 384 to 408 during the 2002 code cycle when 408.21 was included to mandate one neutral for one screw. Prior to 2002 we used the number of conductors outlined on the label in the panel. As long as they were the same size some panels would allow up to five under certain screws.
    Thanks. This is the information I was looking for.

  8. #8
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by Homeownerinburb View Post
    Would it not be correct to say that the code now insists on one wire per screw in every application?

    I cannot think of any place in a residential (what I mostly work on) system where I would be permitted to have two wires at one screw, at all.

    That is not to say that I never stuff a grounding wire from a length of NM under the same screw in the buss as another. But I should not.
    In a panel it is permissible to land more than one equipment grounding conductor under one screw. Look at the label in the panel for more information.

  9. #9
    DIY Senior Member Homeownerinburb's Avatar
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    Quote Originally Posted by jwelectric View Post
    In a panel it is permissible to land more than one equipment grounding conductor under one screw. Look at the label in the panel for more information.
    OK, when next I get deep into one.

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