Cat 6 In Same Conduit with 120 Volt Power

steven765

Member
Location
Mass
Occupation
engineer
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
That one probably came from old systems, but today lives on because of mixed domain environments, and for unshielded cables cross talk is a big concern. Refer to the DCID 6/9 regulations.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Thanks for the code reference Hal, 800.133,
When I see 600V cat5 I tucked in with control panel stuff I am re-doing or servicing I look for a way to re-route and separate it completely.
I have techs argue with me that the 600V cat5 is a permanent barrier and meets the exception 1 in that section:

2017 NEC 800.133(A)(1)(c) said:
Electric Light, Power, Class 1, Non–Power-Limited
Fire Alarm, and Medium-Power Network-Powered Broadband
Communications Circuits in Raceways, Compartments, and
Boxes. Communications conductors shall not be placed in any
raceway, compartment, outlet box, junction box, or similar fitting
with conductors of electric light, power, Class 1, non–power-
limited fire alarm, or medium-power network-powered broad-
band communications circuits.
Exception No. 1: Section 800.133(A)(1)(c) shall not apply if
all of the conductors of electric light, power, Class 1, non–
power-limited fire alarm, and medium-power network-powered
broadband communications circuits are separated from all of
the conductors of communications circuits by a permanent
barrier
or listed divider.
Real 600V listed cable like Allen-Bradley 600 volt rated cat5 or 6 or whatever, might be considered by an AHJ/508A inspector as meeting Exception No. 1 , as the thick outdoor covering and the 600V conductors provide a 'permanent barrier':


Years ago I got into a debate with another 508 panel guy about reclassifying an RS232 as class1,he had it running over some 16 or 18 AWG TFFN so it could briefly pass thru a gutter that had some 120V circuits.
After that RS232 circuit proved to be unreliable I got to reroute it

Is Cat 6 allowed in a JB and Conduit Run that also has 110 Volt Power? Please state code references.
So Rccranford1 in my experience even when people ignore or interpret the code, the signals just dont work well and its better to take another route.
 

shortcircuit2

Senior Member
Location
South of Bawstin
Thanks for the code reference Hal, 800.133,
When I see 600V cat5 I tucked in with control panel stuff I am re-doing or servicing I look for a way to re-route and separate it completely.
I have techs argue with me that the 600V cat5 is a permanent barrier and meets the exception 1 in that section:


Real 600V listed cable like Allen-Bradley 600 volt rated cat5 or 6 or whatever, might be considered by an AHJ/508A inspector as meeting Exception No. 1 , as the thick outdoor covering and the 600V conductors provide a 'permanent barrier':


Years ago I got into a debate with another 508 panel guy about reclassifying an RS232 as class1,he had it running over some 16 or 18 AWG TFFN so it could briefly pass thru a gutter that had some 120V circuits.
After that RS232 circuit proved to be unreliable I got to reroute it


So Rccranford1 in my experience even when people ignore or interpret the code, the signals just dont work well and its better to take another route.
What Code article covers RS-232 and RS-485 data communication wiring? Is it a class 2 circuit? Can serial data communication work on non twisted wiring like tray cable?
 

paulengr

Senior Member
Thanks for the code reference Hal, 800.133,
When I see 600V cat5 I tucked in with control panel stuff I am re-doing or servicing I look for a way to re-route and separate it completely.
I have techs argue with me that the 600V cat5 is a permanent barrier and meets the exception 1 in that section:


Real 600V listed cable like Allen-Bradley 600 volt rated cat5 or 6 or whatever, might be considered by an AHJ/508A inspector as meeting Exception No. 1 , as the thick outdoor covering and the 600V conductors provide a 'permanent barrier':


Years ago I got into a debate with another 508 panel guy about reclassifying an RS232 as class1,he had it running over some 16 or 18 AWG TFFN so it could briefly pass thru a gutter that had some 120V circuits.
After that RS232 circuit proved to be unreliable I got to reroute it


So Rccranford1 in my experience even when people ignore or interpret the code, the signals just dont work well and its better to take another route.
Read the jacket of that CAT 5E or 6 cable carefully. It does indeed state 600 V AWM. Now look in chapter 3 for wire type AWM. This gives all the conditions under which you can use that wire type.

Hmm...seems to be missing!

NEC has a minimum of 18 gauge for chapter 1-3 wiring. Ethernet won’t work on anything that thick. So it cannot possibly be used with general wiring, ever.

But wait you say. AB has smart MCCs. They use that wire. In some MCCs it is literally tie wrapped to the 600 V power conductors. The insulation is thicker than #14. And this is all true. AWM stands for appliance wiring media. It is a catch all term. So if you are AB making MCCs you can use almost any wire you want. AWM means it is customer specific wiring. UL is going to test the final assembly anyway so type AWM is just a pass through. It’s strictly a.component listing so not allowed by NEC.

That same cable is also Listed as PLTC. Under this category you can mix it with other power limited cables, even 120 V lighting, but it is power limited and must comply with those rules.

Ethernet is the most ridiculous example of why the #18 limit is silly. The Ethernet specification calls for an isolation transformer with 1500 V of isolation. The UL/NEC argument has to do with withstanding ground faults but since Ethernet is isolated from ground the argument is flawed but overcoming it would be difficult.
 

steven765

Member
Location
Mass
Occupation
engineer
Maybe give them 3 or 4 cycles. They're finally waking up and allowing ethernet in the main panel for power measurement. It's funny given the three worlds I live in it's a toss up who's slower to adopt any anygiven time. Engineering, Medicine, or the Military.
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Maybe give them 3 or 4 cycles. They're finally waking up and allowing ethernet in the main panel for power measurement. It's funny given the three worlds I live in it's a toss up who's slower to adopt any anygiven time. Engineering, Medicine, or the Military.
People have been putting that 600V ethernet in main panel's for a while now, I have argued against it and lost, AHJ accepts it based on
800.133(A)(1)(c) Exception No. 1.
Read that exception, it does not require a listed chapter 3 wire type, all it needs to do is provide a permanent barrier that the AHJ accepts.
paulengr offers some good insights though.
 

steven765

Member
Location
Mass
Occupation
engineer
People have been putting that 600V ethernet in main panel's for a while now, I have argued against it and lost, AHJ accepts it based on
800.133(A)(1)(c) Exception No. 1.
Read that exception, it does not require a listed chapter 3 wire type, all it needs to do is provide a permanent barrier that the AHJ accepts.
paulengr offers some good insights though.
I was thinking of...


312.8(B) Power Monitoring Equipment. The wiring space of enclosures for switches or overcurrent devices shall be permitted to contain power monitoring equipment where all of the following conditions are met:

(1) The power monitoring equipment is identified as a field installable accessory as part of the listed equipment, or is a listed kit evaluated for field installation in switch or overcurrent device enclosures.

(2) The total area of all conductors, splices, taps, and equipment at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
 

paulengr

Senior Member
The problem is use. You are using CAT wiring in an ungrounded, DC and AC (under 100 Hz) system. But NEC treats all wiring the same. So from a safety issue there isn’t one but since you could theoretically use it as regular power wiring that’s where NEC puts the foot down. Don’t say it can’t happen. I’ve seen CAT 5 used for lots of things. And even if it is strictly communications, big difference between say 10BASE100-T specification and Modbus RS-485 but the same cable will work for either one.

The separation between general and power limited wiring though in a cabinet is also a bit vague but there is general agreement about a couple inches. When I route 600 V cables in switchgear around 5 kV cables we use roughly 4” of clearance minimum. So the same principle should apply.

As far as noise AB did a bunch of tests with welding robots and others years ago and found even unshielded CAT 5E is resistant to arbitrary power interference.
 

rnatalie

Senior Member
Location
Catawba, NC
Occupation
Retired Electrical Engineer
I spent much of my career doing facilities work involving data wiring. There's no requirement or even practical consideration that requires separation or right angle crossing of ethernet twisted-pair wiring from normal power wiring.

As for the NEC, the question is as others pointed out, the combination of your wiring insulation and what terminations for the various systems are present at any given point.
 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
There's no requirement or even practical consideration that requires separation or right angle crossing of ethernet twisted-pair wiring from normal power wiring.
I agree, even though I think its a good idea to maintain separation. I don't have your experience. I did a simple search and clicked on one of the first links and read this in the first paragraph. Does the NEC have such an 8" requirement. What is the Article and section?

Website - [I said:
Written by Don Schultz, Technical Sales Representative and Fluke Networks Certified Technician[/I] ]

 

mikeames

Senior Member
Location
Germantown MD
Occupation
Teacher - Master Electrician - 2017 NEC
No, that is for systems such as FiOS and only covers up to the interface unit (essentially the providers cables).
That does not seem to be the case because they call out 90.2 (B) so FIOS up to the ONT would be on the utility.

840.2 then specifically defines the communications circuit and calls out data.
1613495482344.png

Its does reference 725 over 60 watts. Does that mean if its under 60 watts then its not considered part of 725?

1613495687037.png

Where in 725 does it reference UTP or network cables?
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Communications circuits get interesting really quick and I am no 'know it all' with this stuff,
plus there are a lot of changes in my 2020 NEC but even if you go thru 840 you'll end up at 840.3(A) so that puts you back at Hals reference.
Then the exception that allows a barrier.

Fellon: see 800.2 and its def of communications circuit.

Whichever way you look at it I bet you end up at that 'barrier' and your best chatting with an AHJ.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Ok. It looks like this has changed in every Code cycle. Now, referring to the '17 (I don't have the '20)

645.3(D) Electrical Classification of Data Circuits.
Section 725.121(A)(4) shall apply to the electrical classification
of listed information technology equipment signaling circuits.
Sections 725.139(D)(1) and 800.133(A)(1) (c) shall apply to
the electrical classification of Class 2 and Class 3 circuits in the
same cable with communications circuits.
725.121(A)(4) Listed audio/video information technology (computer),
communications, and industrial equipment limited-power
circuits.
Informational Note: One way to determine applicable
requirements for listing of information technology
(computer) equipment is to refer to UL 60950-1-2011,
Standard for Safety of Information Technology Equipment.
Another way to determine applicable requirements for
listing of audio/video, information and communication
technology equipment is to refer to UL 62368-1-2014,
Safety of audio/video, information and communication technology
equipment. Typically such circuits are used to interconnect
data circuits for the purpose of exchanging
information data. One way to determine applicable
requirements for listing of industrial equipment is to refer
to UL 61010-2-201, Safety requirements for electrical equipment
for measurement, control, and laboratory use –Part 2-201:
Particular requirements for control equipment, and/or
UL 61800-5-1, Adjustable speed electrical power drive systems –
Part 5-1: Safety requirements –Electrical, thermal and energy.
725.121(C) Marking.
The power sources for limited power circuits in
725.121(A)(3) and limited power circuits for listed audio/
video information technology (equipment) and listed industrial
equipment in 725.121(A)(4) shall have a label indicating
the maximum voltage and current output for each connection
point. The effective date shall be January 1, 2018.
...information technology (equipment)...shall have a label indicating the maximum voltage and current output for each connection
point.


Where have you ever seen that on ethernet ports??? Going by the rule and covered by 725, if it's not labeled CL2 or CL3 you are to assume Class 1 and use a Chapter 3 wiring method.

I don't know if any of that has changed in the 2020 but here it's apparent they don't know what they are talking about. There needs to be a clear separation between data cabling (communications) and data cabling carrying power (POE) which is CL2 or CL3.

Art 800 for data and 725 for POE.

-Hal
 
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