Free Illustration Download for Inspection Reports

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Free Illustration Download for Inspection Reports

Main Lugs

Download this free illustration of main lugs from InterNACHI’s Gallery of Inspection Illustrations to boost your inspection reports.

Step 1: Open the newsletter.
Step 2: Scroll to the free illustration.
Step 3: Click it.

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Current standards require energized main lugs before the main disconnect to be protected…

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IMG_51941920×1440 146 KB

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Thank you, Alicia Gromicko.
Health and Happiness this New Year.

PS: Say hello to Ben for me.
Tell Ben, “You’re The Best!”

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There are several issues with this graphic.

  1. A main lug only (MLO) panel requires a 4-wire feeder
  2. The bare conductor on the EGC (ground) bus is the EGC not the neutral. A neutral for the feeder cannot be bare.
  3. The 4th conductor which is missing is the neutral and must be insulated like the two ungrounded conductors and terminate on one of the two neutral buses running down adjacent to the two hot buses with all of the neutral screw holes.
  4. The 4-wire feeder would be type SER cable not SEU.

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Since Dave pointed this out someone has asked me when this requirement entered the code. Here’s the summary of the last three NEC code cycles:

In the 2017 NEC service panelboards were added to the list in 408.3(A)(2) which required a barrier to exposed live parts:

408.3 Support and Arrangement of Busbars and Conductors.
(A) Conductors and Busbars on a Switchboard, Switchgear, or Panelboard. Conductors and busbars on a switchboard, switchgear, or panelboard shall comply with 408.3(A)(1), (A)(2), and (A)(3) as applicable.

(1) Location. Conductors and busbars shall be located so as to be free from physical damage and shall be held firmly in place.

(2) Service Panelboards, Switchboards, and Switchgear. Barriers shall be placed in all service panelboards, switchboards, and switchgear such that no uninsulated, ungrounded service busbar or service terminal is exposed to inadvertent contact by persons or maintenance equipment while servicing load terminations.

In the 2020 NEC this requirement was moved to 230.62(C):

230.62(C) Barriers.

Barriers shall be placed in service equipment such that no uninsulated, ungrounded service busbar or service terminal is exposed to inadvertent contact by persons or maintenance equipment while servicing load terminations.

In the 2023 some additional wording was added to clarify that this protection was for when the service disconnect was opened:

230.62(C) Barriers

Barriers shall be placed in service equipment such that no uninsulated, ungrounded service busbar or service terminal is exposed to inadvertent contact by persons or maintenance equipment while servicing load terminations with the service disconnect in the open position.

Note that this only applies to service equipment. It does not apply (yet anyway) to panels or emergency disconnects that are not service equipment.

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The question that arises to make these illustrations less than useful for a report is, “how does this relate to my home.” I only include illustrations that show the correct installation when a defect is observed. These will accompany a photograph of the actual defect.

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