110.26(A)(4) Limited Access.
Code Change Summary: A new code section addresses equipment with limited access.
Read carefully, this is a BIG change.
In the 2014 NEC®, language was introduced in 424.66(B) to require working space above a suspended ceiling for duct heaters. Many times, once a code change is introduced, there is a future ripple effect and the “what-abouts” start happening.
Question: Well, if a duct heater above a suspended ceiling requires work space, then what about the disconnecting switch feeding the duct heater?
Answer: Well, that’s a good point, why not put in a code proposal for the next code cycle?
In the 2017 NEC®, the language that was specific to only one type of appliance (duct heaters) was removed from 424.66(B) and basically relocated to Article 110 where it now applies generally to anything above a suspended ceiling that may be examined or worked on while energized.
Part of these new requirements include specific size access panels based on if the installation is above a ceiling or in a crawl space.
Below is a preview of Article 110. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2017 NEC® edition of NFPA 70.
2017 Code Language:
N 110.26(A)(4) Limited Access.
Where equipment operating at 1000 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized is required by installation instructions or function to be located in a space with limited access, all of the following shall apply:
(a) Where equipment is installed above a lay-in ceiling, there shall be an opening not smaller than 559 mm × 559 mm (22 in. × 22 in.), or in a crawl space, there shall be an accessible opening not smaller than 559 mm × 762 mm (22 in. × 30 in.).
(b) The width of the working space shall be the width of the equipment enclosure or a minimum of 762 mm (30 in.), whichever is greater.
(c) All enclosure doors or hinged panels shall be capable of opening a minimum of 90 degrees.
(d) The space in front of the enclosure shall comply with the depth requirements of Table 110.26(A)(1). The maximum height of the working space shall be the height necessary to install the equipment in the limited space. A horizontal ceiling structural member or access panel shall be permitted in this space.