Medium voltage installations in structures

Status
Not open for further replies.
M

micary

Member
Thought I read this in the NEC not long ago but can't find it now. Please point me to the article/section relating to installing or running medium voltage through buildings or structures. Thought I had read, "shall be in metallic/rigid conduit".

Thank you
 
micary said:
Thought I read this in the NEC not long ago but can't find it now. Please point me to the article/section relating to installing or running medium voltage through buildings or structures. Thought I had read, "shall be in metallic/rigid conduit".

Thank you
Click to expand...

I don't think you will find it.

take a look at 110 part III that covers installations over 1000V. Especially 110.36.
 
Thanks for responding Bob.
Please allow me to expand. I have stumbled upon an indoor 15KV cable installation above the ceiling. This shielded cable is laying in a cable-tray and turning up and into a junction box where it is spliced. It is considered accessible. In fact, it can and has been walked on in several locations.
Your help has enabled me to find the area I was thinking would apply. Would like your opinion on using 110 Part III 110.31 (B)(1) as an argument, at least from a standpoint of safety.
Your thoughts?
 
micary said:
Thanks for responding Bob.
Please allow me to expand. I have stumbled upon an indoor 15KV cable installation above the ceiling. This shielded cable is laying in a cable-tray and turning up and into a junction box where it is spliced. It is considered accessible. In fact, it can and has been walked on in several locations.
Your help has enabled me to find the area I was thinking would apply. Would like your opinion on using 110 Part III 110.31 (B)(1) as an argument, at least from a standpoint of safety.
Your thoughts?
Click to expand...

For my thoughts on the subject and $5 you could get a cup of mediocre coffee at starbucks.

so you are going to argue that this paragraph requires the cables to be enclosed in metal?

(B) Indoor Installations.
(1) In Places Accessible to Unqualified Persons. Indoor electrical
installations that are accessible to unqualified persons
shall be made with metal-enclosed equipment.
Click to expand...

Equipment. A general term, including fittings, devices, appliances,
luminaires, apparatus, machinery, and the like used as a
part of, or in connection with, an electrical installation.
Click to expand...

I am not sure I would find cables to be equipment as defined in article 100.

Is this a drop ceiling? How is it that unqualified people are allowed up there in the first place?
 
Yes, a drop ceiling. The cable tray suspended about a foot above. Totally accessible. The tray provides an excellent walkway for persons, (A/C mechanics, data system installers, phone, video, fire alarm) to get from one end of the area to the other.
It's not only that I label them unqualified (electrically speaking); they are ignorant as well. Despite the signs and cautionary efforts to detour the activity, there are those who either think they cannot get hurt or don't care. Working in this capacity for a large institution very often demands us to watch out for those who can't or won't, and go the extra mile to see to it they don't, or can't hurt themselves.

If I can't find an article in the code I can hang my hat on, the danger, (in my book) will remain.

Thank you for your time; it is most appreciated!
 
OSHA requires employers to train every employee so they are qualified to do the work they are assigned. It is not just about electrical work.

If they do not know enough to not be walking on cables they are not qualified to do whatever work they are doing above the ceiling and their employer should not be allowing them to do that work until they are properly trained.

Maybe a cover on the cable tray???
 
This might help some.

NEMA VE 2-2013
1.2 GENERAL
WARNING!—Do not use a cable tray as a walkway, ladder, or support for people; cable tray is a mechanical support system for cables and raceways. Using cable trays as walkways can cause personal injury and can damage cable tray and installed cables.
Click to expand...

I seem to recall there is a similar restriction found in NFPA70E.
 
There is a required warning label for cable tray with conductors operating over 600 volts in 392.18(H). Also take a look at 300.37, but that specifically permits the use of cable tray for high voltage conductors or cables. The language in that section dates back to the 1999 code.
 
Status
Not open for further replies.
Top