Results 1 to 3 of 3

Thread: Max Generator Disconnect Height

  1. #1
    Join Date
    Jun 2017
    Location
    WI, USA
    Posts
    198

    Max Generator Disconnect Height

    My design has a single exterior generator in a skin-tight enclosure with a sub base tank. Drawings call for a platform around the enclosure to make sure the on-board circuit breaker does not exceed 6-7".

    The contractor called me and wanted to highlight the additional verbiage of 240.24. This article points us to 225.40 and 230.92: both discuss feeder OCPD not readily accessible and the need for downstream OCPD that are accessible. Admittedly, I typically design to 6'-7" and don't look into it much further (except instance like busways).

    My initial thoughts:

    * This seems to conflict with 230.70(A)(1) and 225.32; although, if the overcurrent protection and disconnect were separate, maybe it wouldn't.
    * Maybe 225.40/230.92 meant to use the term "accessible" rather than "readily accessible," because we would still want the main disconnects to be readily accessible once the qualified person gains access to the locked location when say it has to be locked by 240.6(B) or in an owner/tenant situation.
    * One may consider 445.18 is met by an EPO outside the enclosure either not mounted above 6'-7" or mounted above using exceptions in 404.8

    Although I see where an interpretation may allow the on-board generator circuit breaker to be mounted higher than 6'-7", I lean on the conservative side and hold to the 6'-7" requirement unless the AHJ allows otherwise. Additionally, if I were the owner, I would want the disconnect to be where I could reach it without a ladder.

    Thoughts?

  2. #2
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    33,521
    Quote Originally Posted by publicgood View Post
    My design has a single exterior generator in a skin-tight enclosure with a sub base tank. Drawings call for a platform around the enclosure to make sure the on-board circuit breaker does not exceed 6-7".

    The contractor called me and wanted to highlight the additional verbiage of 240.24. This article points us to 225.40 and 230.92: both discuss feeder OCPD not readily accessible and the need for downstream OCPD that are accessible. Admittedly, I typically design to 6'-7" and don't look into it much further (except instance like busways).

    My initial thoughts:

    * This seems to conflict with 230.70(A)(1) and 225.32; although, if the overcurrent protection and disconnect were separate, maybe it wouldn't.
    * Maybe 225.40/230.92 meant to use the term "accessible" rather than "readily accessible," because we would still want the main disconnects to be readily accessible once the qualified person gains access to the locked location when say it has to be locked by 240.6(B) or in an owner/tenant situation.
    * One may consider 445.18 is met by an EPO outside the enclosure either not mounted above 6'-7" or mounted above using exceptions in 404.8

    Although I see where an interpretation may allow the on-board generator circuit breaker to be mounted higher than 6'-7", I lean on the conservative side and hold to the 6'-7" requirement unless the AHJ allows otherwise. Additionally, if I were the owner, I would want the disconnect to be where I could reach it without a ladder.

    Thoughts?
    permanent stairs or permanent ladder make your platform readily accessible.

  3. #3
    Join Date
    Jun 2017
    Location
    WI, USA
    Posts
    198
    Quote Originally Posted by kwired View Post
    permanent stairs or permanent ladder make your platform readily accessible.
    I agree. The proposed from the contractor was to remove the platform and allow the on-board disconnect to be higher then 6'-7". He wants to say the feeder breakers on the generator switchboard are accessible; therefore, the on-board generator breaker does not have to be accessible.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •