Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at firstname.lastname@example.org. Answers are based on the 2020 NEC.
Why doesn’t 110.26 require all door swings on all electrical rooms, small and large, to swing out for safety reasons. One of our electricians fell and was lying in front of the closed door, making it difficult to get in there to help him. Doesn’t it make sense to modify this rule to have all doors swing out? Why is it based on ampacity?
This requirement is not based solely on ampacity. Section 110.26(C)(3) addresses equipment rated 800 amps (A) or more where there is overcurrent, switching or control devices. If there is an egress door within 25 feet of the nearest edge of the working space, the door must open in the direction of egress and be equipped with listed panic hardware or listed fire exit hardware. The 800A threshold is a value that is subject to change. The original discussion that moved the threshold from 1,200 down to 800A included concerns that a value below that level could impact egress corridors that typically do not allow a door to open into the egress corridor.
Automatic lighting control
Where is the Code reference that states light switches in elevator machine rooms cannot be sensor- or motion-activated. At our new construction project, I pointed out that the light switch will need to be changed. I know they will want in writing where exactly this is stated, and I cannot find it.
The requirements of NEC chapters 1 through 4 as supplemented and/or modified by Article 620 will apply in elevator machine rooms. There is no specific reference in Article 620 that deals with automatic lighting control. Section 620.5 addresses working clearances with a mandatory reference to 110.26(A). While this requirement applies as it is located in Chapter 1, this section does provide modifications to the rules in 110.26. See 110.26(D) that mandates that control by automatic means is not permitted to control all illumination within the working space. This rule does not prescriptively identify types of spaces for required illumination; it identifies working spaces around types of equipment, including service equipment, switchboards, switchgear, panelboards and motor control centers installed indoors. This issue should be addressed in 620.5 with a new first-level subdivision for all elevator machine rooms and related spaces to require illumination and prohibit control by automatic means for the safety of all people performing maintenance related activities in those spaces.
Support of Type SE cable
Why doesn’t Article 338 have a section for securing and supporting like other cable assembly articles? Are there no prescriptive requirements for supporting Type SE cable?
No. The common numbering format in Chapter 3 reserves the XXX.30 section for securing and supporting, as seen in 334.30 for Type NM and 330.30 for Type MC cable. You are correct, Article 338.30 does not exist. However, Article 338 specifically addresses securement and support in 338.10 “Uses Permitted.” You make an excellent point; there should be a section 338.30 that contains the referenced requirements in 338.10, which should be reserved to very simply identifying permitted use. 338.10(A) requires that service entrance cable be installed in accordance with 230.6, 230.7 and Parts II, III and IV of Article 230. This includes Section 230.51(A) that requires service entrance cable be supported by straps or other approved means within 12 in. of every service head, gooseneck or connection to a raceway or enclosure and at intervals not exceeding 30 in. 338.10(B)(4) requires that Type SE cable used for branch circuits and/or feeders be installed with the same securement and support requirements for Type NM cable in Article 334.
Service disconnect location
When installing service equipment, how do we interpret “nearest the point of entrance?” Is it 6 ft., 10 ft. or does the service equipment have to be directly below or above the point of entrance? An inspector required us to move a panelboard used as service equipment 8 ft. It seemed ridiculous because the SE cable was to be behind a finished wall.
Section 230.70 requires a means to disconnect all ungrounded conductors in buildings and structures. The NEC does not require that the service disconnect be installed inside of all buildings or structures. 230.70(A)(1) requires that the service disconnect be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors. The reason behind this rule is extremely important: service conductors are unprotected. The NEC seeks to limit the exposure of unprotected conductors in buildings and structures. If a building owner requests a specific location inside a building or structure, installing the service disconnect outside is always an option. Nearest the point of entrance means exactly what it says. If you can install the service disconnect directly below or above the point of entrance, it must be located there. The NEC does not provide a prescriptive distance because every installation will be different. If the Code allowed 10 ft., you would use 10 ft. for installations that could be installed nearest the point of entrance of the service conductors.
The NEC defines the term “exposed” (as applied to live parts) as capable of being inadvertently touched or approached closer than a safe distance by a person. How does the new requirement for all service-supplied equipment to be provided with barriers that provide inadvertent contact protection impact whether or not the line side terminals are exposed when using 70E?
The requirement that you are referencing in 230.62(C) requires barriers in all service equipment so that no uninsulated, ungrounded service busbar or service terminal is exposed to inadvertent contact by people or maintenance equipment while servicing load terminations. This does not require a metal barrier that completely eliminates contact, as seen in similar requirements in the Canadian Electrical Code. The word “inadvertent” means without intention or done accidentally. This level of protection varies by manufacturer and types of equipment. I have seen some means to provide this protection that resulted in a very poor job and others that were extremely substantial and did an excellent job preventing any possible inadvertent contact.
It is very important to note that NFPA 70E defines “exposed” as applied to energized electrical conductors or circuit parts. The definition is the same, but 70E goes significantly further with additional clarity. NFPA 70E places informational text that exists in the NEC into positive text clarifying the defined term “exposed” (in NFPA 70E) is applied to electrical conductors or circuit parts that are not suitably guarded, isolated or insulated. The presence of exposed energized conductors or circuit parts is a determination made by the employer and qualified people on a case-by-case basis. This is part of the required arc flash risk assessment. An arc flash hazard exists where there are exposed energized conductors or circuit parts and where people will interact with the equipment in a manner that increases the likelihood of an arcing incident. There is no easy button here. Just because service equipment is provided with barriers to prevent inadvertent contact by people or maintenance equipment while servicing load terminations, does not mean exposed energized conductors and circuit parts do not exist.
How to comply?
Commercial service equipment is required to have a label that provides the available fault current. How does installer get those values when we do not always have a transformer to look at and calculate the value? Shouldn’t this be the engineer’s responsibility?
The requirement in Section 110.24(A) is to field-mark the amount of available fault current on service equipment installed in other than dwelling units. The installer is required to apply the field marking. While the engineer could obtain or determine this value, the installer is responsible for applying the label in the field. Informational note No. 2 explains that available fault current values can be obtained from the electrical utility in published or other forms. Many utilities post it on their websites.