Control cable distribution standarts
Control cable distribution standarts
(OP)
Hi all, I am new in US so it was suprise for me to see control signal cables pulled together (Analog, digital) in the same trays, and also see the multiconuctor cable with different voltages iside (48VDC, 120VAC)Personally I don not like it.
Question is if there are codes and standarts for control cables. Thanks in advance.
Question is if there are codes and standarts for control cables. Thanks in advance.





RE: Control cable distribution standarts
An experienced EE can usually look at the signals and equipment involved and make a good call on whether or not the expense of separation is warranted.
There is no code or standard I know of that forces isolation of just analog and digital signals.
Code is primarily to prevent fire and peripherally to prevent blatant electrocution. It cares not whether the system works. There are some codes and standards that do, like the rules governing fire equipment.
A company may have internal standards that state some sort of separation. But just constant separation really makes little technical and economic sense.
The overriding code involved is just for separation based on voltages and the individual insulation ratings of the various conductors.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Control cable distribution standarts
It used to be fairly common to run 120 V ac control wiring in the same conduit with the 480 V motor power, provided 600 V insulation was used for the 120 V circuits.
As Keith says, most companies have internal rules about signal and power segregation.
RE: Control cable distribution standarts
RE: Control cable distribution standarts
Now I have seen where VFDs were run in the same conduit but I believe the reason this was ok was that all the equipment is basically running together. If you have different motors that run at different speeds and such running them seperate from each other is probably necessary. As far as shielded cable being necessary for VFDs I have not seen where replacement of individual wire with shielded cable has made a difference.
Now on wireway you can get the type of wireway that has a metal divider to seperate low level from 480vac.
RE: Control cable distribution standarts
RE: Control cable distribution standarts
Keith Cress
kcress - http://www.flaminsystems.com
RE: Control cable distribution standarts
Roy
RE: Control cable distribution standarts
I'm not sure it ever makes sense to run a 4-20 mA circuit in a tray with 480 V power, even with a barrier. If there are only a few of each, I'd run conduit.
RE: Control cable distribution standarts
We do projects all over the globe so we see lots of different wiring methods. My least favorite is the heavy conduit used South of the border.
There are lots of occasions where splitting a tray with a metal barrier makes sense, I have even seen 2 barriers on occasion with MV, LV & 4-20 on one tray.
In Canada you often see motor and control "Teck" armored cables on the same tray without a barrier.
Regards
Roy
RE: Control cable distribution standarts
You're right - I've seen a lot of things installed in many different ways. But that doesn't mean I would design it that way myself.
Cheers,
Dave