Cat 6 In Same Conduit with 110 Volt Power

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I doubt it-- also check the informational note #1

(C) Conductors of Different Systems.
(1) 1000 Volts, Nominal, or Less. Conductors of ac and dc
circuits, rated 1000 volts, nominal, or less, shall be permitted to
occupy the same equipment wiring enclosure, cable, or raceway.
All conductors shall have an insulation rating equal to at
least the maximum circuit voltage applied to any conductor
within the enclosure, cable, or raceway.
Secondary wiring to electric-discharge lamps of 1000 volts or
less, if insulated for the secondary voltage involved, shall be
permitted to occupy the same luminaire, sign, or outline lighting
enclosure as the branch-circuit conductors
Informational Note No. 1: See 725.136(A) for Class 2 and
Class 3 circuit conductors.
Informational Note No. 2: See 690.4(B) for photovoltaic source
and output circuits.
 

paulengr

Senior Member
CAT 6 is ALL either Listed as PLTC. That means it cannot be run with other non-PLTC all wiring as per Chapter 7. You can run it with lighting circuits and similar power limited applications, see again chapter 7.

The problem is as per chapter 3 and UL power wiring is limited to a minimum 18 gauge. CATegory cable, all categories, cannot achieve the required shunt capacitance rating at 18 gauge setting the maximum to 22 gauge. So it can never be power cable.

The exception is that you can certainly buy 600 V CAT 6. Belden makes it. But it is AWM meaning it can be used as part of a Listed assembly such as part of say a drive but not going from the assembly to somewhere else in conduit. Yes I know you are plugging it into an Ethernet port with 1500 V of isolation via an isolation transformer. UL ignores that fact.
 

GoldDigger

Moderator
Staff member
Low voltage and high voltage can not be on the same race way. The can also interfere with the transfer of data.
Low voltage and high (in the consumer sense) voltage in the same raceway is not really the issue. It is power (Chapter 3) versus Limited Power (which happens to also be limited in maximum voltage).
 

paulengr

Senior Member
Low voltage and high voltage can not be on the same race way. The can also interfere with the transfer of data.
That last part is true of serial such as RS-232 but false on Ethernet which has a notch at 50-60 Hz. Allen Bradley did a lot of testing on this with UTP. I’ve seen grounding issues but not interference in Ethernet. BUT it’s a huge issue with RS-232 and sometimes RS-485.
 

paulengr

Senior Member
Low voltage and high (in the consumer sense) voltage in the same raceway is not really the issue. It is power (Chapter 3) versus Limited Power (which happens to also be limited in maximum voltage).
It is not a voltage issue. You CAN purchase 600 V insulated AWM CAT cable from Belden for example. It is used in some drives and switchgear. Same jacket as any other 600 V rated power cable. This is just like running special high voltage XHHW wiring with 5 kV jackets in the power side of MV switchgear and motor starters.

But CAT 5E and 6 has a maximum gauge requirement of 22 gauge in order to meet impedance requirements. UL mandates minimum power cable size of 18 gauge for ground fault purposes (make sure the fuse trips before the cable vaporizes). Physics dictates that CAT can’t be made that large so thus CAT 5E or 6 cannot meet any of the regular power cable requirements (chapter 3).

I mean inside say an industrial control panel you can literally have a CAT 6’with a 600 V AWM rating tie wrapped to 500 MCM THWN-2. It is legal and it works. But it’s also part of a Listed assembly...the manufacturer has to get an NRTL to approve the panel. But the moment it exits the enclosure it falls under NEC rules and needs separate raceway.
 

flashlight

Senior Member
Location
NY, NY
"I mean inside say an industrial control panel you can literally have a CAT 6’with a 600 V AWM rating tie wrapped to 500 MCM THWN-2. It is legal and it works. "

Wow, if you say so I believe you...We were always required to not parallel it with power, and to cross at right angles.
 

paulengr

Senior Member
"I mean inside say an industrial control panel you can literally have a CAT 6’with a 600 V AWM rating tie wrapped to 500 MCM THWN-2. It is legal and it works. "

Wow, if you say so I believe you...We were always required to not parallel it with power, and to cross at right angles.
That information is correct in unshielded low speed communications. There are three things that make Ethernet inherently different. First every electromagnetic emission is a combination of an electrostatic and magnetic field. The twists in twisted pairs are important. Every twist sees the fields in the opposite polarity so it totally cancels both fields. Second there is 1500 V of isolation across a balun at both ends so it breaks any magnetic induced field that could be induced by the loop. Shielding helps improve resistance to electrostatic fields if you use ScTP instead of UTP but since both ends are grounded it enhances magnetic fields by making the shield a loop antenna. In practice around power it’s mostly magnetic fields so shielding may or may not improve things but generally makes it worse.


I’ll try to find the AB article with actual results in it.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
The idea behind twisted-pair cable is assuring that both conductors receive any interference equally (common-mode), so it can be ignored by the receiver (differential amplifier), and only the desired difference signal be fed through (common-mode noise rejection).

The higher the twist rate of the cable pairs, each pair having a slightly different rate for minimal cross-talk, the higher the frequency of noise able to be ignored. Twisted-pair audio cabling works this way, too, but are usually shielded because of the frequency range.
 

paulengr

Senior Member
I've been trying to debunk that idea for years but I still keep hearing it. It probably came from IT people or BICSI who are "over the top" in their own world.

-Hal
The cable crossing thing is real and often quoted. There are two reasons. If you have two cables in parallel you can induce a voltage from one to the other. Obviously this is minimized in straight cables. In twisted pair every half twist exposes it to the opposite field so it is 100% cancelled. Also in the near field you get a 3 dB interference rejection by angling cables 90 degrees in terms of treating the cables as antennas and treating them as antennas. So there is a lot of wisdom in this when it comes to say low level analog signals from thermocouples, load cells, RS-232, and even 10 VDC analog signals. Very different from say 4-20 mA current loops, RS-485, Ethernet, and CAN, which are much more interference resistant.
 

myspark

Senior Member
Location
SCV Ca, USA
Occupation
Retired EE
I've been trying to debunk that idea for years but I still keep hearing it. It probably came from IT people or BICSI who are "over the top" in their own world.

-Hal

It is interesting and thus-- catches my attention when someone shows confidence albeit assertiveness in making a point.
I'm anxious to hear what your "debunking" ideas are.

Data corruption is REAL and it's a burden that needed to be addressed when transmitting data.
Corruption can occur in different ways.. . .voltage spikes, data loss due to induced voltage, lack of protective shield to preclude unwanted packet gaps, unscheduled shutdown as in sudden loss of power, lightning strikes, etc.

Every data packet that is streaming down the data highway has it's own unique identity, the message it is carrying, the destination address, the length of the packet and most important-- the manner it is being delivered.
All of these attributes are generated and reported to the client computer where the data were meant to be received.
If any of the details are not received by the client as described-which also indicate that a page is not found- those particular packets are discarded. . .and an error 404 code message will show up on the screen.
Voltage spike, can damage a packet which will render that packet unusable.

Induced voltage from nearby power lines as in the case of cat5 cable running alongside can cause damaged packets. It can be mitigated by crossing power- carrying- conductor at right angle (90 degrees)--which essentially lessen its exposure as oppose to running alongside (parallel)

If your debunking idea means an outright denial that data loss doesn't exist-- and just some sort of osmosis belching out ot IT professionals' heads--I think you owe it to readers of this forum to prove that data loss doesn't exist.

Now, try debunking that.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
I've been trying to debunk that idea for years but I still keep hearing it. It probably came from IT people or BICSI who are "over the top" in their own world.

-Hal
I'm not going to disagree with you on Ethernet cabling. I was in the force and motion control world, hydraulic and electric. Our control devices (servo, proportional, and pressure valves) (electric servo motors) typically had frequency response to the very low hundred Hertz. Our signal cabling was typically high impedance (4.7-47 kOhm), rarely 4-20 mA, and in a cable containing 4 to perhaps 12 "cores" including DC power. Coupling from power, depending on level, would commonly be seen in the controlled variable OR in the intentional dither by the electronic device. Frankly, the addition to the dither wasn't usually a problem. The beating with dither signals did weird things however. I often found 2 problems, interrupted shielding and parallel runs, to create these symptoms. In a control panel, I requested 12" spacing to power cabling if parallel, and 90 degree crossing when crossing was required. More than 1 time we found magnetic shielding to help things (often a sleeve of EMT). We denied responsibility if signal (with their DC power) cables shared conduit from machine to cabinets.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
...I mean inside say an industrial control panel you can literally have a CAT 6’with a 600 V AWM rating tie wrapped to 500 MCM THWN-2. It is legal and it works. But it’s also part of a Listed assembly...the manufacturer has to get an NRTL to approve the panel. But the moment it exits the enclosure it falls under NEC rules and needs separate raceway.
Yes, the manufacturer can install it that way in their equipment, but even inside the listed equipment the electrician cannot install it that way.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
It is interesting and thus-- catches my attention when someone shows confidence albeit assertiveness in making a point.
I'm anxious to hear what your "debunking" ideas are... Now, try debunking that.
I'm not going to go and try to find it because it was years ago, but suffice it to say that actual tests were done by a cable manufacturer and other interested parties that show that there is no effect on the data on unshielded UTP when in the proximity of wiring carrying power. I even think the tests were done upping the potential beyond the usual 120/240. Ethernet is pretty damn robust.

You wouldn't happen to be a member of BICSI, would you?

-Hal
 
Top