I am installing 12kV MV cable within a termination section. The cable is being terminated onto a high bus. What is the maximum length of unsupported cable permitted from the conduit stub-up to the fastening point? I see where the vertical support of MC cable has a maximum vertical distance of 6 feet, but I see nothing in that regard for Medium Voltage Cable. Please stick my nose in the appropriate code section. Thanks.
12 kV cable vertical support requirements
- Thread starter kuchenig
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Re: 12 kV cable vertical support requirements
There may not be a section dealing with this activity.
I would install a cross brace and lace nylon type line around the conductors and brace. The brace can be unistrut.
Leaving the cable unsecured can cause a failure later on.
There may not be a section dealing with this activity.
I would install a cross brace and lace nylon type line around the conductors and brace. The brace can be unistrut.
Leaving the cable unsecured can cause a failure later on.
charlie
Senior Member
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- Indianapolis
Re: 12 kV cable vertical support requirements
We usually use a Kellums grip that is similar to a Chinese handcuff.
We usually use a Kellums grip that is similar to a Chinese handcuff.
Re: 12 kV cable vertical support requirements
Appreciate the responses but my real question is What constitutes a problem? How does one determine whether or not there is even a concern.
Obviously smaller conductors will cause less weight stress. A short length of heavy conductor could be more of a problem than a long length of light conductor.
Is the conclusion simply that it is a judgment call on the part of the designer and/or the installer as to whether or not to provide supports?
I thought the Code had something in it about supporting long lengths of cable within vertical risers such as in buildings. If so there must be some kind of code expressed concern at least in some applications. Thanks for your comments.
Appreciate the responses but my real question is What constitutes a problem? How does one determine whether or not there is even a concern.
Obviously smaller conductors will cause less weight stress. A short length of heavy conductor could be more of a problem than a long length of light conductor.
Is the conclusion simply that it is a judgment call on the part of the designer and/or the installer as to whether or not to provide supports?
I thought the Code had something in it about supporting long lengths of cable within vertical risers such as in buildings. If so there must be some kind of code expressed concern at least in some applications. Thanks for your comments.
Re: 12 kV cable vertical support requirements
Cable support inside switchgear is not covered in the NEC. The section you are thinking about is for conductors inside vertical raceways. (Table 300.19 A ) How you support the cable inside the gear is going to be covered in the manufacturers installation instructions. There is usually diagrams that show you how to lash and support the conductors (like Bennie mentioned)in order to meet the AIC rating of the gear. If you don't follow this the conductors can severely deflect under fault conditions causing excessive damage.
Cable support inside switchgear is not covered in the NEC. The section you are thinking about is for conductors inside vertical raceways. (Table 300.19 A ) How you support the cable inside the gear is going to be covered in the manufacturers installation instructions. There is usually diagrams that show you how to lash and support the conductors (like Bennie mentioned)in order to meet the AIC rating of the gear. If you don't follow this the conductors can severely deflect under fault conditions causing excessive damage.
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