SEPARATION OF DIFFERENT CABLES

[pristava]

The Owner is not ready to invest for new Cable Tray.The new 5 kV cable is provided to be installed ( small section only)together with -
600 V existing power cables
24 V DC existing signalisation cables
The Engineer working for Owner says that is acceptable. But that is not ... acceptable.

 

[tulum]

Don't all the cables in a cable tray have to be rated for the voltage rating of the highest cable?...

 

[DougMSOE]

Usually power cables (5kv (and up)) are kept in trays by themselves.
600vac, 250vdc, 240vac, 125vdc, 120vac are usually grouped together ac a voltage group.
Instrumentation go in separate trays.

 

[busbar]

For ANSI regions, review 2002 NEC Article 392 as a minimum standard. IEEE Std 141 {red book} §12 is another reference.

 

[amptramp]

Medium Voltage (MV) cables may be installed in the same tray as 600V or less cables per NEC 2002 392.6 (F).

However, I would not mix MV and Controls in the same tray unless spacing and shielding were looked at VERY closely.

 

[RajT]

It is better of course if there is a separation between the dc cable and the 5kV cable of say 300mm.
If the eng is adamant that it would be ok to run them in the same tray then one can argue that there may not be any problems with the inteference induced in the dc cable and that all will be well.
If you have to abide by his ruling then you should ensure that the 5kV cable is furthest away from the dc cable and hope for the best on that basis that should you experience problems in the future then you can alays rerun the 5kv cable in a new adjacent tray. To allow for this you should allow for the 5kV cable with some slack to ensure that it can be re run to suit.
On the assumption that all cables are armourd or screened, you might just get awa with it.