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    Does a pendant drop required a plug at either end?

    Does a pendant drop required a plug at either end?

    New postby JohnSTI on Tue Aug 30, 2016 2:23 pm

    I have several CNC Machines at my facility that looks like Pendant drops were going to be used but someone decided to hard wire the flex cord at each end. Is this a violation?
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    Re: Does a pendant drop required a plug at either end?

    New postby Jerry Peck - Codeman on Tue Aug 30, 2016 4:57 pm

    Is that a disconnect switch in that box up on the rafter/beam? The disconnect should be down near the equipment too.

    From what your photo is showing, my answer would be: No, that is not a permitted use under 400.8 Uses Not Permitted and 400.7 Uses Permitted of the NEC.

    If the drop from the box at the beam was in raceway down to a box on the wall near the equipment, the disconnect located at that lower box, and flexible cord run between a box which is now lower and closer to the equipment and to the equipment itself, my answer would be "depends" ... as it would depend on if the equipment meets the allowances permitted in 400.7 Uses Permitted and not under 400.8 Uses Not Permitted.

    Currently it does not meet 400.7 Uses Permitted: (1), (2), (3), (4), (5), (6), (8), (9), (10), or (11).
    - It might meet 400.7 Uses Permitted (7), but that is not shown in the photo either way - you would need to determine that on-site.

    Currently it seems to fall under 400.8 Uses Not Permitted as it meets; (1), (4), and possibly (7) ... unless it meets 400.7(7) based on 400.8 stating "Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:"

    Unless that cord, installed from a lower junction box and then run as a shorter piece to the equipment, meets 400.7(7) "Prevention of the transmission of noise or vibration.", then it would be 400.8 Uses Not Permitted.

    HOWEVER, as currently installed hanging from the rafter/beam, even if it was installed to meet 400.7(7) for transmission of noise or vibration, it still meets 400.8 Uses Not Permitted because it is being used "(1) As a substitute for the fixed wiring of a structure."

    2014 NEC 400.7 & .8 flexible cord uses.jpg
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    Re: Does a pendant drop required a plug at either end?

    New postby JohnSTI on Wed Aug 31, 2016 7:06 am

    Jerry the box up top in the rafters is only a junction box. There is no disconnect switch except the one located on the CNC machine it's self. The only other is the breaker located in the panel box where the conduit run in the rafters originates from. I included another picture that give you a slightly closer look but is the same kind of connection as in the original post, but from a different CNC machine. The connection in this photo though happens to be 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. 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?...

    * So the Flex cord doesn't meet 400.7(1) as a pendant drop? why the lack of a plug?
    * 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?
    * 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.

    Thanks
    Jerry

    I'm absorbing your knowledge....keep it coming....lol
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    Re: Does a pendant drop required a plug at either end?

    New postby Jerry Peck - Codeman on Wed Aug 31, 2016 11:38 am

    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.
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