Ethernet in same conduit is line voltage / breaker panel. Under which conditions is it legal?

[exp]

I need advice from experts here.
My understanding is that no low-voltage wiring (which includes Ethernet) is allowed to exit an enclosed raceway (conduits, junction boxes) that contains line voltage. I am not sure about the exact reasoning but I assume there is the chance that wiring might fail and low voltage conductor could short with line voltage conductor. Low Voltage count run in the same raceway as line voltage assuming it is never brought out (e.g., communication wire from one device to a relay which are both installed in enclosed junction boxes).

There is so much (contradicting) discussion about this but nothing I can find provides clear NEC references. It just sounds people have "opinions" they categorically defend. I am sure there must be some exceptions:

1. Emporia's Vue3 is an energy meter for fixed install inside a residential breaker panel. It features an Ethernet connector. It is UL certified. Emporia insists it is safe and legal to bring in Ethernet into the breaker panel to connect with their Vue3
2. Enphase Envoy is an enclosure that connects to line voltage and also has an Ethernet connector. While we may argue that the Ethernet cable itself cannot run through the same conduit as the line voltage, even if we bring out Ethernet via another knockout, it would still exit the "enclosed raceway"
3. There are Panduit 600V Ethernet cables which suggest they can be legally in the same conduit as line voltage. In this case, it seems the only reason is that the cable can sustain 600V (like line voltage) but I could still run them in the same conduit as line voltage and bring them in/out via clamps in a junction box, for example.

• Which of these examples are legal? Is Emporia correct?
• What are the exact conditions according to NEC to run low voltage (in particular, Ethernet) in the same conduit/junction box/panel as line voltage?
• What is the exact reasoning? Is it risk of low voltage shorting with line voltage? Is it insulation capabilities of low voltage conductors (which are usually, but not always, <600V rated)?
• In example (1), it wouldn't make sense if there are no additional conditions on how to bring in the Ethernet cable. No minimum spacings, no insulation, no requirements on bushings etc?

 

[petersonra]

Ethernet is a class 2 circuit. Read up in the class 2 article. There is no problem putting Ethernet and power wires in the same enclosure as long as the required separation is maintained.

 

[suemarkp]

I did not think ethernet is specifically class 2. Would think article 800 is more appropriate for it. The rules are about the same in 800.133. Be sure to read all the exceptions, as that is what you'll need to use.

 

[petersonra]

I did not think ethernet is specifically class 2. Would think article 800 is more appropriate for it. The rules are about the same in 800.133. Be sure to read all the exceptions, as that is what you'll need to use.

Ethernet is most definitely class 2.

 

[suemarkp]

It fits the CL2/CL3 limits of voltages and power, but I've not seen a CL2 or CL3 mark on ethernet switches or other ethernet devices. I thought the power supply had to have a CL2/CL3 marking in order for it to be considered that.

 

[jaggedben]

Ethernet fits pretty firmly under 725.60(A)(4), which would make it Class 2 or 3.

To answer the original question, the distinction between an enclosure and raceway is very important, as it is allowed for ethernet and power to coexist in an enclosure under certain circumstances and restrictions, but not for them to share a raceway. See 725.136, there are a lot of details to compliance.

The only allowance for sharing a raceway (in theory) would be under 725.136(H), which would require using a Class 1 method. But since ethernet typically uses UTP and that is basically by definition not a Class 1 method. Theoretically AFAIK there could be an UTP cable listed for Class 1 but I've yet to see that exist.

Note that 'ethernet' is a actually a software term, and the actual cable is UTP or Cat5,6,7 or whatever. So theoretically possible to run 'ethernet' a different way but that's not too meaningful in the real world.

 

[suemarkp]

Thanks for the 725.60(A)(4) reference. That's been in the code book longer than I realized.

What about 725.136(I)(1) or (2). That seems to be a catch all bucket. Surrounding the cat5 cable in a firmly fixed flexible tubing seems to be an easy way. If someone could market cat5 cable with a TC marking, that would help too. An innerduct or maybe even ENT inside a larger raceway may also work under part (I).

 

[tortuga]

Even if the code allows it does not mean it will work.
I have worked on jobs where we removed a bunch of 600V shielded cat5e that was ran with power conductors because the error rates were off the charts. We had to run dedicated comms conduit.
That was awhile ago, some of that was RS-232, RS-485 and some ehternet.
These days I bet your could get a fiber cable and have no issues.

 

[petersonra]

Even if the code allows it does not mean it will work.
I have worked on jobs where we removed a bunch of 600V shielded cat5e that was ran with power conductors because the error rates were off the charts. We had to run dedicated comms conduit.
That was awhile ago, some of that was RS-232, RS-485 and some ehternet.
These days I bet your could get a fiber cable and have no issues.

I suspect it was not Ethernet. Ethernet is highly resistant to noise. Rs232 has lots of issues with noise.

 

[exp]

Wow, indeed not as straight forward ...


To clarify, all 120V mains voltage in residential is Class 1?

@petersonra , what you are referring to is Article 725, I guess. And specifically 725.136.



Regarding (3): 725.136(I)(1) explicitly lists "TC cables". Also, according to the datasheet, "TC [...] • Designed to be installed in the same channel as cables operating at 600 V – Minimum conductor size is 18 AWG – Barriers are not required, however, high voltage cables are very heavy and therefore may present a crush risk cables".

Does this mean I can place a Panduit TC Industrial Ethernet Cable in the same conduit as mains voltage and bring it out via a bushing? Is 725.136(I)(1) the reason for it? And if no, why not?

Regarding (1): Which code section would cover bringing Ethernet into a subpanel and connecting it to the Vue3? Is it 725.136(D)(1), meaning that the UTP cable just needs to be 6mm from the other conductors?

 

[jaggedben]

Wow, indeed not as straight forward ...


To clarify, all 120V mains voltage in residential is Class 1?

No, 120V is power and lighting. Aka mains power. Class 1 is signal and control circuits that don't fall under the limits for Class 2 and 3. It generally has more robust wiring methods than Class 2 or 3.

@petersonra , what you are referring to is Article 725, I guess. And specifically 725.136.

Regarding (3): 725.136(I)(1) explicitly lists "TC cables".
Also, according to the datasheet, "TC [...] • Designed to be installed in the same channel as cables operating at 600 V – Minimum conductor size is 18 AWG – Barriers are not required, however, high voltage cables are very heavy and therefore may present a crush risk cables".

Does this mean I can place a Panduit TC Industrial Ethernet Cable in the same conduit as mains voltage and bring it out via a bushing? Is 725.136(I)(1) the reason for it? And if no, why not?

That cable document is what I'd call a product brochure, not a datasheet. The datasheet would list exactly what product standard (UL something) that it's listed to if it's listed as a Class 1 cable. They seem to be claiming that it's Class 1 cable but I'm not totally convinced.

725.136(I)(1) refers to separating Class 2 and 3 physically from power and light in a different cable or raceway. So it's not really addressing your questions and not relevant.

Regarding (1): Which code section would cover bringing Ethernet into a subpanel and connecting it to the Vue3? Is it 725.136(D)(1), meaning that the UTP cable just needs to be 6mm from the other conductors?

Yes.

 

[suemarkp]

725.136(I)(2) let's you sleeve things for separation. You need to firmly fix the sleeve. In a panel full of power and lighting conductors, you would want to sleeve the ethernet cable and perhaps use screw down cable ties to secure it in place. Details will depend on the meaning of firmly fixed to the inspector.

 

[brycenesbitt]

Here's an old thread on the topic

Running control wiring in power conduit for EV Charger amperage control. 725.26(B)(1).

I'm looking for some help with NEC code interpretation wiring associated with EV charging. This is for a series of "Wallbox" brand EVSE chargers which have an RS-485 control circuit. In short they measure the current at the main using CT clamps, and then throttle the vehicle's charging rate to...

forums.mikeholt.com

---
Remember the data conductors have to be associated with the power being switched (they were thinking control buttons and e-Stops).
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TL;DR
Article 725.49(B), 2008, says that for Class 1 circuit conductors, "Insulation on conductors shall be suitable for 600 volts. Conductors larger than 16 AWG shall comply with Article 310. Conductors in sizes 18 AWG and 16 AWG shall be type..."
In this case the RS-485 conductors can be 18 or 22 gauge, shielded by a foil, and protected by a 600V jacket and additionally enclosed in a sheath.
--
Also note that only half the Wallbox coms are RS-485.
The seemingly identical coms run an absolutely miserable to parse Modbus protocol.

 

[brycenesbitt]

Note that 'ethernet' is a actually a software term, and the actual cable is UTP or Cat5,6,7 or whatever. So theoretically possible to run 'ethernet' a different way but that's not too meaningful in the real world.

For example, the once popular Thicknet, Ethernet over coax with vampire taps. Or today's MoCA.