Please tell me about the standard separation distance between power and signal cable trays installed vertically.

Also whta is the priority of installing power cable tray and signal cable tray? I mean which should go on top?

Thanks in advance.

 

The Cable Tray Institute can answer a lot of your questions. http://www.cabletrays.com/
You might want to check out their website.

Regards,

Bruce

 

try out http://www.mikeholt.com

 

> 1) standard separation distance between power and signal cable trays installed vertically.
>
> 2)Also what is the priority of installing power cable tray and signal cable tray? I mean which should go on top? <

POWER

Please clarify with power voltage (480, 120, 13.8kV, etc.). For the "lower" voltages (i.e. low level instruments on one side of a tray with a metallic divider then 120VAC on the other side of the same tray) sometimes power can be in the same tray... here we only do this with digital signals (on/off valves, limit switches). A good rule of thumb from DOE critical installations is:

Trays for cables of different voltage levels should be stacked in descending order with the higher voltage. Instrumentation trays should always be at the bottom. At least 12 inches of clear space should be provided between tray levels.

We also add that instrument trays cross electrical trays at 90 degrees if the 12 inch rule "gets violated".

For safety-critical systems, here is some advice from a DOE handbook:

Cable Tray Separation:
In general, physical separation of cable trays for redundant safety-class circuits should be maintained by a minimum of three feet horizontal separation. Vertical stacking of redundant cable trays should be avoided, if at all possible, but where such arrangement is employed, minimum vertical spacing should be five feet between the two groups. Where this is not practicable, barriers will be provided or rigid steel conduit and thermal barriers should be used. Divided cable trays should not be used to separate redundant systems.

The cable tray system should be designed and installed according to the requirements of IEEE-384.

Hope this helps,
C3

 

You'll want to install the highest power level trays on top, with succedingly lower signal levels going down. This keeps the low level signals as far as possible from high voltage/current carrying conductors. Also, it eases installation of large cables, since they are in the top tray, and also if you are installing a "Protectowire" fire detection system, it will run across the top tray.

Keep cables carrying power in excess of 500V or 200A at least 20" from low level signal circuits, i.e. analog, thermocouple signals, less than 100 mV or 1 mA, or other noise sensitive signals. These low levels conductors should always be in enclosed tray. For power cables less than 500V and 200A, stay at least 10" from low level signals.