JohnSTI wrote:... the box up top in the rafters is only a junction box. There is no disconnect ...
Curious as to what that white spot on the original photo is? That is what I thought was a switch disconnect.
... utilizing a strain relief connector into the junction box. The origin photo from the first post seemed to be using a compression type connector at the junction box but has a tension strain relief located about 6ft away from the junction box.
The weight of the cord needs to be supported at the connector unless the connector is specifically listed for that use - without information on the connector being listed for supporting pendant drops, then install a tension strain relief support where it exits the box and connector, and have the cord exit straight down, not out the side as that causes the cord to bend greater than its require bending radius and puts a strain on the cord and the connector which neither is listed or rated for.
You mention that the flex cord may be in violation of 400.8(4) is this because of the tension strain relief from the original post photo?
Those photos show what looks like (zooming in on the photo gets grainy and loses clarity due to low resolution) white nylon cable straps attached to a beam with the flexible cord being held up by those cable straps.
As a side note, white cable straps are not very UV resistant and are not rated for use outdoors, only indoors, and, while that is "indoors", the lighting inside may be putting out enough UV to deteriorate white cable straps/ties over time. i.e., keep an eye any white cable ties/straps used like that and replace as needed/if needed (the safest bet is to use black cable ties/straps inside when exposed to high levels of lighting which contain UV - some lighting types produce more UV than other types, if the straps get hard and stiff, the straps are deteriorating, black cable ties/straps are listed for outdoor use and are UV resistant).
* So the Flex cord doesn't meet 400.7(1) as a pendant drop? why the lack of a plug?
- Correct. The NEC does not define "pendant", however, the NEC specifically states at the beginning of Article 100 that it only defines terms which are deemed necessary to be defined, not common terms, and "pendant" is a common term and is used to describe something which is suspended or hanging from something, in electrical use an example could be a pendant light, in your use, an example could be a pendant receptacle ... except that there is no receptacle, the flexible cord is simply being used from high above to a machine below.
* The conduit and junction box in the rafters was run the same time as the flex cord for the purpose of powering the CNC so it wouldn't fall under 400.7(11) becasue the junction box isn't an electrical outlet and wasn't per-existing?
- Regardless of when the flexible cord was run, it would have to end with the end hanging loose and something on the end of it, such as a lighting fixture, receptacle outlet, switch to control something, etc. In the case shown, the cord is simply run down to the machine.
- If the flexible cord hung straight down with a receptacle outlet on the end of the cord, that would be a pendant.
- It the flexible cord hung down, was draped to a wall, then hung down ... that part is being used as a substitute for fixed permanent wiring and should not be flexible cord - that should be in conduit down to a box with a receptacle outlet if the machine is cord and plug connected, or to a flexible cord if the transmission of noise and vibration needs to be reduced (flexible conduit could be used for that purpose to an extent), or use a rigid raceway (such as PVC/EMT/IMC/RMC) if noise and vibration is not an issue.
* I 'm sure the flex cords wasn't used for 400.7(7) because other CNC have pendants drops (flex cord) have a plug/receptacle connection at the CNC (not hardwired) like some others, but that's not to say that particular machines are more sensitive than others.
- It may be possible that the flexible cord pendants for the other machines also helped with reducing the transmission of noise and vibration, it is also possible that the flexible cord was simply easy to hang down out in the middle of the floor in an approximate location where a machine may be set, rather than drop a rigid raceway which has limited flexibility.
- Either way, pendants are permitted for some uses, so saying the other pendants are incorrect is more difficult than addressing the one which does not meet any of the requirements as installed. If this flexible cord was hanging straight down and had a receptacle outlet on it end, it could be questionable as being okay or not okay, but this one is not installed hanging straight down ... so it is not a -pendant, and it meets some of the 'uses not permitted' while not meeting any of the 'uses permitted'.
I can see where a CNC machine may create noise and vibration which would not want to be transmitted and would need a flexible connection - are the CNC machines mounted on vibration and noise isolation pads, or are they mounted directly to the floor? If mounted directly to the floor, that would be an indication that vibration and noise from the CNC machines are not issues which need to be addressed, thus flexible cords likely would not be needed to isolate vibration and noise.