2023 NEC Section 310.12 and Sub-Panels

by | Jul 9, 2024 | NEC Code, NEC Section 310.12, Sub-Panels

I was recently asked the question:

“Can 2023 NEC Section 310.12 and the corresponding table be used for sub-panels in a dwelling?”

Sub-Panel. Rocky Mountain Chapter of the IAEI.This question prompted the following blog, highlighting the most common violation in my experience, associated with Section 310.12.  The remainder of this blog is my answer to the question, hope you enjoy.

Can Section 310.12 be used?  Hmmm, I would say maybe, this section has some conditions, the one most often violated being the feeder or service conductors supplying the dwelling, supply all loads associated with the dwelling.  Section 310.12 permits feeder and service conductors to be sized in accordance with sub-divisions (A) through (D), in short (A) and (B) require the conductors supply “the entire load associated with a one-family dwelling, or the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling”.

Example of a common misapplication would be a sub-panel supplying only the loads associated with a garage.  First off, a garage is not a dwelling, secondly, if the sub-panel only supplies some, but not all loads associated with the dwelling, 310.12 cannot be applied.

It is important to remember 310.12 does not give exception to conductors having an ampacity at least equal to, or greater than the calculated load.  Lastly, it needs to be mentioned 2023 NEC Section 240.4(B) may permit conductors to be protected by an OCPD of the same ampere rating as that of Table 310.12.

For example, where a 4/0 AWG aluminum feeder supplies a basement sub-panel, if the sub-panel does not supply all the loads associated with the dwelling, 310.12 is not applicable, however, the ampacity of a 4/0 does not correspond with the ampere ratings of a standard OCPD, and 240.4(B) permits the next higher standard size to be used.  In this example it is Section 240.4(B) that permits a 200-ampere OCPD to protect the 4/0 aluminum conductors and not Section 310.12.

Author
Chris Papp

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NEC Changes and Adoption

by | Sep 7, 2022 | NEC Code

NEC Changes and Adoption

Did you know…

NEC Changes and Adoption

​It is approaching that time again, bikini season, whoops…. Wrong article, NFPA 70 Public Input Stage.  Most, if not all of us in the electrical industry are well aware the NEC is revised, then updated every three years for the latest version.  This blog will not go into any further discussion of government adoption, but the link below to the NFPA website provides a map of NEC State adoption, color coded by the code cycle year adopted.

http://www.nfpa.org/NEC/NEC-adoption-and-use/NEC-adoption-maps

NEC Standards Development Process

The NEC process can be broken down into four steps.  It all begins with the issuance of a public notice that the NEC revision process has begun, this is usually within a few days of a newly released edition of the NEC.  Fun time, if you are involved in the electrical industry, you or somebody you know have at some point discussed how a particular Section of the NEC could be or have been improved by the code making panel (CMP).  Reality is anybody in the electrical industry can have a significant impact on the NEC, it is truly a consensus standard.

After issuance of public notice that the NEC revision process has begun anybody can submit a public input on NFPA’s website.  Public inputs are most often submitted by interested parties such as the IAEI but can be submitted by any individual as well.

The Public Input or PI

Public inputs will require identification of the submitter, and the organization or company affiliation of the submitter.  The submitter can also simply be unaffiliated with any company or organization, just a NEC geek wanting to be heard.  PI’s must identify the specific Code Section of the proposed revision.  Next the PI will need a statement of the problem and substantiation for why the change is necessary.  All that’s left now is the proposed wording of the revised text or the wording to be deleted.

In conclusion I leave all with the infamous words of Keith Loftland that would be spoken several times during any of the many educational seminars he had instructed for IAEI.  “I look forward to your public input”.

Author
Chris Papp

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NEC Requires Products and Materials be Listed

by | Jul 1, 2022 | 2022, Listed Products, NEC Code, NRTLs, OSHA

NEC Requires Products and Materials be Listed

Did you know…

NEC Requires Products and Materials be Listed

Dustin Behounek . IAEI Rocky Mountain Chapter InstructorDid you know that, although the NEC requires products and materials be listed or field evaluated, not all code articles contain a specific statement requiring listings? In general, most sections you will find an XXX.6 that requires listings or field evaluations. In 2017, the NEC underwent some more changes to how every article is structured and there was also a push to have an XXX.6 placed in all articles. There was some pushback in certain articles keeping that requirement out. NEC 110.3 (B) and (C) deal generally with who is allowed to ‘List’ or ‘Certify’ a product and how these are to be installed and used. There is an informational note under 110.3(C) that directs attention to OSHA which is the organization that recognizes qualified testing laboratories. The current list of nationally recognized testing laboratories (NRTL’s) is found on the OSHA website at https://www.osha.gov/nationally-recognized-testing-laboratory-program/current-list-of-nrtls. There are currently 21 NRTL’s.

If An Item Is Not Listed

Inspectors, installers, and consumers should always verify that the materials and Inspectors, installers, and consumers should always verify that the materials and equipment installed are listed by an NRTL. IAEI Rocky Mountain Chapter.equipment installed are listed by an NRTL. If it is found that an item is not listed, it can be field evaluated. There are many field evaluation bodies (FEB’s) that can perform a field evaluation. You can find a list of these at https://www.iasonline.org/services/field-evaluation-bodies/.  Once a field evaluation is requested or required the chosen FEB will evaluate the item in the field at its final location or address of installation. When complete, there will be a report made available and a label applied to the item. The report should be sent to the inspector for approval.

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Circuit Breakers and Fused Switches

by | May 2, 2022 | 2022, Circuit Breakers and Fused Switches, NEC Code, Overcurrent Devices

Circuit Breakers and Fused Switches

Did you know…

Did you know that there are restrictions to where you can install circuit breakers and fused switches? Those restrictions can be found in article 240.24(A) through (F) of the 2020 NEC. Circuit breakers and fused switches are called overcurrent devices. They need to be readily accessible and installed so the center grip of the operating handle is not more than 6 feet 7 inches above the floor or working platform when it is in the highest position unless the device is for busways (as provided in 368.17(C), supplementary overcurrent protection (described in 240.10), overcurrent devices described in 225.40 and 230.92, or where adjacent to the utilization equipment they supply, the access can be portable like a ladder. There is an exception, found in 240.24, that allows a tool to be used where they are installed within listed industrial control panels or similar enclosures. Regardless of the location, the working clearances of 110.26 would still apply.

Ready Access

Circuit breakers and fused switches are called overcurrent devices.All occupants need to have ready access to all overcurrent devices that supply power to conductors in that occupancy unless permitted by 240.24(B)(1) and (B)(2). Where service and maintenance for electrical are provided continuously by the building management, the service and/or feeder overcurrent devices supplying more than one occupancy are permitted to be accessible only to authorized personnel. An example would be in multiple-occupancy buildings and guest rooms or guest suites. Where service and maintenance for electrical are provided continuously under building management supervision, the branch circuit overcurrent devices for guest rooms or suites WITHOUT permanent provisions for cooking shall be permitted to be accessible only to authorized personnel.

Where Overcurrent Devices Cannot be Installed

Overcurrent devices cannot be installed where they are subject to physical damage. There is an informational note here that directs you to 110.11 concerning deteriorating agents.

Overcurrent devices cannot be installed near easily ignitable materials like in clothes closets. This would also include linen storage closets and the like.

Overcurrent devices cannot be installed in bathrooms of dwelling units, dormitory units and guest rooms or guest suites (other than supplementary protection).

Overcurrent devices cannot be installed above the steps of stairways. This use to be a regular practice but was found to be hazardous to those needing access.

You might come across panelboards that were installed under a previous edition of the NEC in areas like bathrooms, clothes closets and over the steps of stairways. You should always consult your local AHJ to determine if you can install new overcurrent devices in these panelboards.

TIA – Tentative Interim Amendment

by | Apr 1, 2022 | 2022, NEC Code, Tentative Interim Amendment

TIA – Tentative Interim Amendment

​Did you know that on December 8, 2021, the NEC issued TIA 20-15 for 406.9(C), exception No. 2?

A TIA is a Tentative Interim Amendment to the NEC. These can be found by navigating to https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=70

Click on Current & Prior Editions and you find all Issued Amendments under the TIA heading for the 2020 Edition. You can download and print these to place in your codebooks for reference. They are placed automatically in the digital version of the NEC.

This TIA 20-15 was issued to address the use of receptacles for electronic toilet or personal hygiene devices i.e., electronic bidet seats. 406.9(C) created a zone of 3 feet horizontally and 8 feet vertically from the top rim of a bathtub or threshold of a shower stall where no receptacles are allowed to be installed. This obviously created an issue for the electronic toilet and personal hygiene devices as the toilets are commonly placed near the tubs and showers. The NEC now allows a single receptacle (simplex) to be installed in that zone if it meets the requirements of Exception No. 2. When inside the 3 x 8-foot zone, the receptacle must be a single (simplex) receptacle installed in a readily accessible location on the opposite side of the toilet from the tub or shower but NOT behind the tank. What the exception does not address is the use of the electronic bidet devices where the toilet is set between the bathtub and the shower stall and there is no place outside the defined zone. No receptacle would be allowed to be installed for a bidet in this instance.

As of the writing of this article, there have been sixteen TIA’s issued for the 2020 NEC. These include TIA’s for the following references:

725.121(C) – issued prior to printing; 210.52(C)(2) – issued prior to printing; 725.121(C),a second TIA – issued prior to printing; 240.67(C) and information note – issued prior to printing; 240.87(C) and informational note– issued prior to printing; Annex D3 – issued prior to printing; Table 430.252 – issued prior to printing

Issued AFTER printing – 551.71(F); 800.100(B)(2) informational note and figure caption; 356.10(8); 520.21; 520.53; 210.8(F) [This TIA does NOT negate the Colorado State Variance which includes ALL HVAC installations on dwelling units]; 706.50; 406.9(C), Exception No. 2; 250.114(3)e and 250.114(4)e

Of the sixteen TIA’s issued there are nine that were issued after printing the NEC.

See our Blog Page for more articles from the Rocky Mountain Chapter of the IAEI.

Did You Know…

by | Mar 3, 2022 | 2022, Job Site, NEC Code

Did You Know…

Did you know that for the installation of a temporary job-site trailer, you need to refer to several NEC articles? Let’s see how to navigate this.

For the temporary installation of a job trailer (manufactured buildings and relocatable structures), one would think you would begin with Article 545. However, the section that should first be visited is Article 590. I know what you’re thinking… “It’s just temporary.” Nevertheless, while reviewing Article 590 we find that there are some things that are relaxed and many that have more restrictive rules.

To begin, installations must comply with ALL other applicable articles except as SPECIFICALLY modified by 590. In Colorado, there is also a relaxed requirement for the grounding electrode system. Colorado allows a single rod, pipe (which you cannot use due to lack of listing), or plate electrode to be installed for all temporary installations that require a GES.  However, 590.3 lists the time constraints for a temporary installation as “During the Period of Construction.” The temporary installation is to be removed immediately upon the completion of construction. 590.4 then tells us that the service must comply with parts I through IV of article 230. If the unit is to be provided electrical power through a feeder, it must have overcurrent protection in accordance with 240.4, 240.5, 240.100 and 240.101. The conductors used for the feeder are permitted to be within cable assemblies or multiconductor cords or cables as identified in table 400.4 for hard usage or extra hard usage (typically type S through SOOW). For flexible cords, you will need to use column A of Table 400.5(A)(1) to find the conductor sized to fit the need, up to #2 AWG at 80 amps max. For all other approved wiring methods, you will use 310.16 to find the ampacity. You are also permitted to use Type USE cable in a raceway underground for the purpose of temporary installation only.

Next, 590.4(J) requires that cable assemblies and flexible cords and cables must be supported to prevent physical damage and cannot be installed on the floor or ground (extension cords are exempt from this). Flexible cords containing fine stranded conductors like class I, K and M, may not be rated for use with the terminal lugs of the panelboards and OCPD’s installed in/on the trailer.

Additionally, we must visit Article 545, Part II, Relocatable Structures. Part II is a recent revision to the 2020 NEC that was taken from previous cycles within Article 550. Previous code text from Article 550 that applied to mobile homes used as other than dwelling units, has now been relocated to Part II of Article 545 and is titled “Relocatable Structures.” Part II of Article 545 applies to relocatable structures, like jobsite trailers.

Finally, The State of Colorado requires that all manufactured buildings that were manufactured after 1991 bear a DOLA/DOH insignia. These requirements are found in 8CCR 1302-14 4.21.2. Without the insignia, the unit will not receive power. If manufactured prior to 1991, the insignia is not required and proof of date of manufacture is to be provided. The vehicle registration will show the date of manufacture.

In conclusion, we would need to use articles 590, 545, 230, 240, 250, chapter 3, and 400 from the NEC as well as state statutes to install electrical power to a job site trailer (manufactured building/relocatable structure). What do we do with a converted semi-trailer that needs power? Hmmm… That will have to be tabled for another day.

Thank you, and I hope this is helpful!