Results 1 to 7 of 7

Thread: Battery Rooms declassified per 480.10?

  1. #1
    Join Date
    Apr 2016
    Location
    Georgia
    Posts
    509

    Battery Rooms declassified per 480.10?

    My understanding is battery rooms containing vented lead acid storage batteries should be classified as Class I, Division 1 (Group B).
    Per Article 480.10, if sufficient ventilation is provided within the room it need not be classified under Article 500. We have several of these rooms on site. They are quite small and probably do not meet the required CFM for declassification. However each room contains a vent fan, gas detector, air-flow switch and trouble alarm to DCS. The Area Class drawing shows them as Class I Division 2 - not Unclassified. Isn't this a bit overkill?

  2. #2
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,230
    One of my favorite Sections from NFPA 497 [2017 Edition](Underlines mine):

    5.6.4 When classifying buildings, careful evaluation of prior experience with the same or similar installations should be made. It is not enough to identify only a potential source of the combustible material within the building and proceed immediately​ to defining the extent of either the Class I, Division 1 or Division 2; or Class I, Zone 1 or Zone 2classified areas.

    Where experience indicates that a particular design concept is sound, a more hazardous classification for similar installations may not be justified. Furthermore, it is conceivable that an area be reclassified from either Class I, Division 1 to Class I Division 2, or from Class I, Division 2 to unclassified, or from Class I, Zone 1 to Class I, Zone 2, or from Class I, Zone2 to unclassified, based on experience.
    A Battery Room built to the requirements of Article 480 does not need to be classified. In other words, you don't need to declassify what wasn't needed to be classified in the first place.

    Even before Article 480 was introduced it was recognized (by those with sufficient experience) that the hydrogen generation rate and its subsequent diffusion rates did not warrant classifying a battery room.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #3
    Join Date
    Apr 2016
    Location
    Georgia
    Posts
    509
    Quote Originally Posted by rbalex View Post
    One of my favorite Sections from NFPA 497 [2017 Edition](Underlines mine):

    A Battery Room built to the requirements of Article 480 does not need to be classified. In other words, you don't need to declassify what wasn't needed to be classified in the first place.

    Even before Article 480 was introduced it was recognized (by those with sufficient experience) that the hydrogen generation rate and its subsequent diffusion rates did not warrant classifying a battery room.
    Nothing on the area classification drawing states the room was built to Article 480. Everything is designed for Class I, Division 2 environment, i.e. conduits are sealed and a Nema 7 Encl is installed on the wall for the Air Flow Switch. I feel confident the room is ventilated at min 1 CFM per square foot capacity (NFPA 76) and therefore meets the requirement of 480.10; but I cant prove it. The only two viable options I see here are CID1 or unclassified.

  4. #4
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,230
    Quote Originally Posted by Dale001289 View Post
    Nothing on the area classification drawing states the room was built to Article 480. Everything is designed for Class I, Division 2 environment, i.e. conduits are sealed and a Nema 7 Encl is installed on the wall for the Air Flow Switch. I feel confident the room is ventilated at min 1 CFM per square foot capacity (NFPA 76) and therefore meets the requirement of 480.10; but I cant prove it. The only two viable options I see here are CID1 or unclassified.
    Well, the NEC requires it be designed to Art 480; so odds are, I wouldn't classify it although I'm not too familiar with NFPA 76 requirements.

    That "gas detector" you mentioned in the OP might land it in Section 500.7(K) which virtually makes Division 2 automatic; i.e., if you think you need a gas detector, you must think there is a sufficient possibility of an ignitable atmosphere.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  5. #5
    Join Date
    Feb 2003
    Location
    New York, 40.7514,-73.9925
    Posts
    4,568
    Some folks design battery rooms with more than the minimum thinking that it makes it safer, but sometimes it confuses the classification issues for those that come after.
    Ron

  6. #6
    Join Date
    Apr 2016
    Location
    Georgia
    Posts
    509
    Quote Originally Posted by ron View Post
    Some folks design battery rooms with more than the minimum thinking that it makes it safer, but sometimes it confuses the classification issues for those that come after.
    I agree. Furthermore the room resides in a prefab metallic building (13.8kV switchgear is in the adjacent room separated by a sheet metal wall). Which makes me believe even more the room is in reality, unclassified.
    I’m used to seeing battery rooms with concrete walls — unless of course air movement within the room/building meets the criteria for Art 480 in which case it wouldn’t matter.

  7. #7
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    5,230
    I forgot, I'm sorry, although they are quite common, Art 480 doesn't actually require an isolated battery room at all. The key issue with regard to classifying the location surrounding the battery installation is Section 480.9(A).
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

Posting Permissions

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