MV Cable & Cable Tray. 1

[ksavoie]

If I understand the code correctly I can put 5KV and 15KV MV Cable in the same cable tray without haveing any barriers or up sizing the 5KV's insulation. Is this correct?

 

[Marmite]

Which code? Technical requirements and statutory requirements vary enormously between regions and/or states.
Regards
Marmite

 

[gepman]

If you are referring to NFPA 70 (NEC) I didn't see anything (in my old 2002 code, I am still out of the office) that specifically allowed it or specifically disallowed it. Cable tray is specifically mentioned as NOT being a raceway which would disallow 5kV and 15kV in the same conduit.

Can you name the specific portion of the specific code which allows you to think that you can do this? I don't think that the cost difference between the two insulations levels is enough that I would mix the two.

 

[BJC]

NEC 392.6 F says you can do it. You Can't put 600 volt cable with MV Cable. No good reason I just like the ideal.

 

[BJC]

I lost part of that last post.
I ment to say I would install a divider in the tray and seperate the 5KV from the 15 KV. I don't know of a code requirement but I like the Ideal.

 

[Zogzog]

I dont see a problem if they are sheilded cables.

 

[burnt2x]

From reliability stand point, I don't think it is advisable. We don't want to get blacked-out for a long time should the 5kV lines get fried and you lose your 15kV lines at the same time!
My guiding principle: "Don't put all your eggs in one basket!" Just my honest opinion.

 

[lansford]

The optimum would be to uses 3/c cables or better yet an interlocked armor or CLX type etc
JIM

 

[MxGxK]

I don't have the NEC here at home, but I'm almost certain it states that cables of voltages both above and below 600V can be placed in the same tray. However, it states that the above 600V cable must be MC cable. This is all from memory, of course.

 

[peebee]

MxGxK, you are correct per NEC 392.6(F), to mix <600 and >600V cables in the same tray, teh >600 must be type MC and there must be a barrier between the <600 and >600 cables.

There does not appear to be any such requirement for 5 & 15kV cables, however. NEC would appear to let you mix them as you see fit, with no particular additional requirements for mixing cable (beyond what is required for all cables of same medium voltage).

 

[peebee]

Zogzog mentioned: "I dont see a problem if they are shielded cables." Refer to NEC 300.3(C)(2), very last paragraph, "...conductors having nonshielded insulation and operating at different voltage levels shall not occupy the same enclosure, cable, or raceway".

I think this could be reasonably interpreted to require shielding for both your 5 & 15kV cables (although there certainly might be an argument there). 15kV cable is usually shielded, but 5kV is often unshielded, so this might pose a problem for you....

 

[dpc]

I think NEC now requires any cable over 2 kV to be shielded. Might have been a change in the 2005 NEC. Or maybe I dreamed that?

 

[gepman]

A cable tray is NOT a raceway, enclosure, or cable so I don't believe the NEC 300.3(C)(2) applies.