NEC 422.6: Does this preclude any electrical changes to your machines? No more adding VFDs?

[rabler]

Ok, who is a NEC code guru? Any electricians? Haven't seen @Bi11Hudson posting recently ...
I was digging through the NEC after looking at load requirements (wiring sizes) supporting VFDs. Just chasing NEC concepts, and came across this one that is new in the 2017 NEC revision:

• 422.6: All appliances operating at 50 volts or more shall be listed.

"Listed" generally means UL or other similar safety organization (my read of other parts of the code).

I'm guessing UL listing doesn't apply to modified equipment. Sounds like, at least on paper, that any machine repaired with other than factory supplied parts are therefore a NEC code violation. I'm guessing technically if you add a VFD you can't plug it into a NEC 2017 code building. (Fortunately my shop was built under NEC 2014 which was in effect for Indiana last year). Sounds like FAA requirements for airplane parts.

If so, I'd guess 99% of us including me are going to just ignore this, and I'm not trying to play safety police. Just seeing if any of the collective wisdom can shed any light on this. I'd guess 1/2 the stuff bought on Amazon or Ebay from overseas sellors isn't "listed". In practice I think NEC code applies when a residential building is inspected and approved for use/occupancy. Not to what the end user plugs in after the fact. (Commercial buildings may be subject to ongoing inspection) Anything after that is an argument for insurance company not paying?

 

[mksj]

I think the key word is "appliance", I do not consider machines used in the garage would fall under the term appliance. Most mainstream VFD's are UL listed that I have seen, these all have been 20Hp and under. Larger industrial types probably fall under other electrical code requirements. UL listing is for electrical devices that use plugs and receptacles.

Understanding Requirements for Appliances​

 

[woodchucker]

Ok, who is a NEC code guru? Any electricians? Haven't seen @Bi11Hudson posting recently ...
I was digging through the NEC after looking at load requirements (wiring sizes) supporting VFDs. Just chasing NEC concepts, and came across this one that is new in the 2017 NEC revision:

• 422.6: All appliances operating at 50 volts or more shall be listed.

"Listed" generally means UL or other similar safety organization (my read of other parts of the code).

I'm guessing UL listing doesn't apply to modified equipment. Sounds like, at least on paper, that any machine repaired with other than factory supplied parts are therefore a NEC code violation. I'm guessing technically if you add a VFD you can't plug it into a NEC 2017 code building. (Fortunately my shop was built under NEC 2014 which was in effect for Indiana last year). Sounds like FAA requirements for airplane parts.

If so, I'd guess 99% of us including me are going to just ignore this, and I'm not trying to play safety police. Just seeing if any of the collective wisdom can shed any light on this. I'd guess 1/2 the stuff bought on Amazon or Ebay from overseas sellors isn't "listed". In practice I think NEC code applies when a residential building is inspected and approved for use/occupancy. Not to what the end user plugs in after the fact. (Commercial buildings may be subject to ongoing inspection) Anything after that is an argument for insurance company not paying?

Hmm, good point about Bill. I hope he's ok. He's been off since Jan

 

[rabler]

I think the key word is "appliance", I do not consider machines used in the garage would fall under the term appliance. Most mainstream VFD's are UL listed that I have seen, these all have been 20Hp and under. Larger industrial types probably fall under other electrical code requirements. UL listing is for electrical devices that use plugs and receptacles.

Understanding Requirements for Appliances​

I chased this down in the same vein as your VFD wiring spec, playing with definitions. You quoted IIRC 430.122, which is for Circuits which contain power conversion equipment. (Contain, not provide power to). Doing some research, that seems to be intended for vfd installs where the vfd and motor are part of the building approved structure and wiring. Such as operating elevators, commercial hvac ventilation, etc.

Looks to me like anything plugged into an outlet is an appliance. NEC has specific provisions for appliances containing motors. One of those points is to use the tagged capacity by a listing authority for determining the wiring size. Which led me to this.

It is certainly not obvious to me that using UL listed parts means the end device is UL listed . Can you provide further support for that? I’d think UL would want a separate testing fee. They are a private company. For one thing if there is any other than the VFD and motor, there is enough load and ground issues that the vfd “listing” isn’t applicable. And they probably want to review your ISO9001 certification to see you have suitable quality control on your “product”.

*My* personal take away is quoting obscure bits of NEC is fruitless unless you have a legal degree, electrical degree, electricians license and state inspection authority. Basics are pretty clear, but getting into essentially this level is pointless at the hobby level.

But your comment does support the idea that if it has a plug, NEC applicablity gets … weird. I’m going to stick to making my tools plug-in based rather than disconnect wired for that reason. I think it at least provides a good argument against a denied insurance claim. You might consider that in terms of your liability in putting out “plans” and suggestions etc for conversions. Generally you have pretty good advice and are a great resource, but this feels like a stretch of that. I think you’re on shaky ground making any where near definitive statements with this. Part of the problem is neither NEC or UL are legal governing bodies . They are adopted by state’s legislative processes that have no understanding of electricity. And the rest of us are left to sort out the mess. Just my thoughts, FWIW.

 

[mksj]

The NEC establishes listing requirements, and UL meets those requirements in what it certifies (bearing in mind that the term “Listed” as used in the NEC is not the same as “UL Listed”). What I have seen posted elsewhere is that electrical devices with an attached plug typically falls under UL, if hard wired it is NEC. Generally, the NEC applies to field installation and wiring. Manufactured items and package systems that are shipped pre-wired are generally not covered by the NEC - that is where UL comes in. There is also UL Listed which refers to a stand alone device, vs. UL Recognized parts which are the individual components that may be used in a machine. VFD's do not come with plugs, unless they are part of a machine. In the case of most machines like the 1440EV in another discussion, it does not come with a plug, so it is not a UL machine, although the VFD is UL listed. The UL listing you indicated states "Article 422 covers electric appliances used in any occupancy if they are fastened in place, permanently connected, or cord‑ and plug-connected. The meat of this Code Article is in Parts II (Installation) and III (Disconnecting Means)". The rest of the article discusses appliances in the house and not machines. UL certifies the device to meet certain specifications/operating conditions, NEC determines the specifications it needs to meet. UL deals with complete appliances/individual parts, not modified by the user. If you replace/modify a UL listed machine then it no longer meets their listing unless noted otherwise. Adding a VFD to a machine would fall under NEC, the cord and plug would need to meet NEC requirements, the plug and receptacle would also need to be UL rated I assume.

Even the expert electricians tend to disagree on the interpretation of the electrical codes, and then you have local code on top of that. At the end of the day it is the electrical inspector who approves the compliance with codes.

 

[Reddinr]

Bottom line is to make the equipment as safe or safer than it was when it was purchased/listed. If you are not selling it, the only risk is your own.
If you make it as safe or safer than as-built, and maintain the equipment as needed, the risk of fire / shock / burn is very low. I have never seen an inspector look twice at plug-in equipment at a residence but they certainly can if they desire.

Here is a link that talks about reconditioning Listed Equipment. This is a step that is less than modification so you can bet that modifying equipment by adding a VFD requires the removal of the listing mark too to maintain listing.

https://www.ul.com/resources/faqs-about-safety-certification-reconditioned-equipment


Product listing process, - for anyone interested - :
(Unfortunately I've been through this process countless times. It is not any fun as the rules seem to change with the test/evaluation personnel.)

UL Lists products with plugs/cords AND direct-wired devices.

For manufacturers that make listed products for sale, the process includes UL (or ETL or TUV or Intertek or other) to review all components within the product as well as the overall product. For the most part the manufacturer is allowed to substitute almost any equivalent "Listed Device" they want within the product as long as it meets the requirements for the equipment. In the test report, a plug on a cord might be described as "LISTED ATTACHMENT PLUG, 20A 240V" Or something to that effect. Note there is no manufacturer/model number.

On the other hand, "Recognized Components" used in end-use equipment are evaluated and/or tested as part of the end product evaluation. If you want alternate Recognized Components they are also evaluated at the time of the UL Listing evaluation of the product. The allowed model numbers/manufacturers are usually listed out in detail. Sometimes a model series is allowed. Each recognized component is also evaluated to its requirements by its manufacturer/UL and always includes "conditions of acceptability" which must be met in order to use it within listed equipment.

For a device "in the field" to keep its UL Listing and be reconditioned or modified in the field with alternate parts not covered by the listing report, UL and others have field evaluations that can be done. This is typically done by a customer in cooperation with the manufacturer. UL techs show up, look over the changes, possibly testing them. If OK, a label is re-applied and a large invoice is generated.