OT: Running e-net with 120AC

HMI station is being placed in a location that is awkward to route conduit to because of overhead crane issues, but thats where the customer wants it. I prefer to run the 120 for the HMI and the ethernet cables in separate conduits, however in this case it may be simpler to run both is the same 3/4" conduit. The run length will be between 40 and 50 feet (12 to 15 meters). 120V current is less than 5 amps. There is also 6 points of discrete 24 VDC I/O in the conduit.

Can I get away with it? What if I use a shielded cord for the 120V?

I wouldn't really brag about it but I have seen ethernet cable in wire trays with 1/0 and greater feeding distrubution panels. And for the recond no I did not do it. Just saw it.

That said I think if you use a sheilded cable for your 120 vac you should be ok.

Use good Cat-6 cable!

I also don't recommend it, but if you decide to go that route, at least make sure to use top quality Cat-6 cable and not the cheaper stuff Cat-5. Cat-6 features more stringent specifications for crosstalk and system noise. BlackBox sells really high quality ethernet cable.

http://en.wikipedia.org/wiki/Category_6_cable

On a side note, Cat-7 will someday be available (10 gigabit ethernet) where each wire pair is individually shielded!

I've been crawling through the code book to see if its even allowed and what I've found so far could be interpreted either way. I haven't found a definitive paragraph on it.

Alaric said:

HMI station is being placed in a location that is awkward to route conduit to because of overhead crane issues, but thats where the customer wants it. I prefer to run the 120 for the HMI and the ethernet cables in separate conduits, however in this case it may be simpler to run both is the same 3/4" conduit. The run length will be between 40 and 50 feet (12 to 15 meters). 120V current is less than 5 amps. There is also 6 points of discrete 24 VDC I/O in the conduit.

Can I get away with it? What if I use a shielded cord for the 120V?

Click to expand...

Although not recommended, it can still be done. When to be careful is the proximty to motor voltages,especially those motors driven by VFDs. We have one client we inherited who had ethernet cable strapped to a raceway full of motor wires. Since our company became involved with this client, right away we advised them to move that particular ethernet run in rigid conduit. In the months since, 6 more motors on VFDs have been added into that particular raceway. Now we have issues of ethernet switch ports failing, and even one of our techys felt a shock from this offending ethernet run.

Our in house master sparky figures this unprotected ethernet run is acting as a giant antennae picking up all the EMI from those VFDs. We have since put in a bid to this client to run the ethernet in grounded rigid conduit. Now they are taking our original warning serious.

Curlyandshemp,
are they using XPLE insulated wires? Because the output of VFDs is a PWM square wave, the phase to phase voltage difference between leads from different drives can be over 1000Volts, way beyond the rating of the THHN wire often used for drives. When running multiple drives in the same raceway you should use drive cables.

(paraphrased by me)

The NEC on running multiple voltages in one raceway:
it is allowed, if all the conductors in the raceway have insulation rated for the highest voltage present in the raceway. I also seem to remember some condition about all wiring being related to a common system or piece of equipment (i.e. machine/process), but that's seems obviously to be the case in your application.

You could run fiber. You would have to get some converters though.

http://www.everythingfiberoptic.com/cartgenie/prodList.asp?scat=55&gclid=CM_Mq9Lc15gCFRwDagod-3wrcw