QUESTION
After talking with one of our commissioning leads. He made the requests that if possible, to use Teck cable for control and power cables as they can strip them with relative ease. Looking at some catalogs, i can see they come with a grounding conductor but no shield. Which is what i would like to use, and in my experience they work well for protecting against voltage spikes, noise, etc. I am just wondering if anyone here would have any insight or preference over regular shielded cable (vs Teck) for control cables going from the substation yard into the building and between panels.
I asked our supplier at Anixter, apparently getting shielded cable 14AWG is special order. She wrote:
Shielded power cables are not used for most other industries until you get into medium voltage cable. Standard stocking teck and tray type cables would be unshielded only in 14AWG and larger.
REPLIES
marks1080
Teck doesn’t provide the best shielding properties for control cables, especially VHF transients (think switches pulling arcs). Concentric copper shielding is best. Looks like a corrugated copper sleeve between the inner and outer sheaths. Also, cable shield needs to be grounded. Personally, I would not accept Teck for control cables. This often gets suggested by construction crews (easier for them to deal with fewer types of cable), but they have zero insight into the shielding properties.
We dictate rather harshly exactly what type of cable we want. We also buy enough of it that they gladly provide it.
Anixter and Shawflex are the same thing right? Because that’s where we get a lot of our cable. Ask for M582 spec specifically. I can tell you we have active material for 7C#14AWG cable of this type. I don’t like the statment you got saying shielded power cables are not typically used until medium voltages. The cables we buy are rating for 600V so that makes no sense at all - that is 100% bullshit. Shielded cables must be used, especially if you are using IEDs. If you are converting from electromech to IED and all of a sudden you have weird things happening and the only thing you changes was the relay, it almost always means the cable shielding was never properly done. Also, keep in mind the 60HZ noise isn’t a problem. It’s the 100MHz ++++ noise that damages equipment.
Regarding TECK cable: Do not use this for control circuits. TECK is only for power supplies (typically AC or heavy DC trunks). The drain wire on the teck cable IS NOT RATED to handle transient noise, especially high frequency.
If they offer to send you something with a tape shield do not accept. they are notorious for the shield breaking inside the cable when they are being pulled.
SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=448208
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