ethernet and AC in conduit

I know it's not recommended or allowed by the NEC , but I'm wondering if anybody knows how likely I am to have problems if I run ethernet and AC (120 volt) in the same conduit for 20 meters....

thanks, Steve

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Unlikely to have technical problems BUT should there be a fire/injury and the insurance company finds out they will void your coverage.

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I have 240v and 100-base-T running alongside each other in several locations in the house. No issues.

I very much doubt that's true, unless they have an exclusion in their policy documentation. On what grounds would they do it?

Reply to
Mark McIntyre

None at all if you run the Ethernet over fiber.

If not, don't whine if your fire insurance is void...

Reply to
David Lesher

hmmm - we ran the AC in the required conduit and metal boxes to totally contain the AC/fire gremlins.

The "low voltage" stuff in the drop/plenum ceiling was a little trickier... Either - it was the more expensive "plenum" cable, hung from the I-beams, or run inside a pipe/conduit just for physical protection and it would exit from the conduit at a patch panel on either end.

Same with the low voltage telco/phone wiring.... which you didn't mention.

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In comp.dcom.cabling ps56k wrote in part:

What would a "problem" be for you?

In theory, ethernet and 60 Hz AC won't interfere with each other, so separation and isolation are irrelevant. Now, if that AC is going to some noisy electrics (arc welders) or to some sensitive equipment, there might be some interference.

But you are taking an unapproved risk and depriving others of a layer of protection. Break the insulation, either by a pulling scar or mechanical accident, and they are _much_ closer to a fatality. Do you want other people setting traps for you? Don't set them for them!

-- Robert

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Robert Redelmeier

As far as I know, it will likely work fine.

As you say, not allowed by the NEC. Some time ago, I predicted that you could run ethernet with 240VAC common mode on the cable, but I never got around to trying it. (Also not allowed by the NEC.)

Use cable ties onto the outside of the conduit.

-- glen

Reply to
glen herrmannsfeldt

This would be an American thing?

Don't think the UK equiv have the same level of paranoia.

Gruesome, and tricky if the conduit is underground !

Reply to
Mark McIntyre

I know of a case where someone added additional wiring to their home and it burned down because a wall fixture they had added had a much larger than rated wattage bulb installed and was left on continuously and ignited the wall. It was a newer home and apparently there was language regarding code compliance. They tried to hang the inspection company but the application and inspector's notes showed a lower outlet count than what was installed.

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"Use cable ties onto the outside of the conduit."

Also not allowed ny the NEC either if you want to be pedantic.

If you can find cat 45 cable with a jacket rated at >120v it is perfectly legal to run it in conduit with line conductors. I have even heard compelling arguments that the romex insulation/jacket is sufficient "separation"

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Very good. This extended dialogue about insurance and such is probably useful for others....

[Philosophy/Rant warning]: but personally, I have never had to live or work in an insured environment, thank God. My father is an insurance agent, but I consider most insurance (including health) to be a cure worse than the disease, both on a society-wide basis and personally, unless you are one of those ugly people who game the system at the expense of others.

Anyway, I am able to deal with reality and not worry about insurance and litigious society. My own home in the US is an old adobe with a metal roof (all new wiring installed illegally by me) so they never would insure it anyway, even if I wanted. I'm self-insured and like it that way. I try to do things practically correct more than literally.

As far as safety, living in a developing country (Mexico) one sees both how useful (at times) and how ridiculously anal (other times) the hyper-safe US mentality can be. I'm not advocating it, but here, people wire things up with open connections, no tape, no wire nuts, no boxes, and it still works ! OK, they do usually have boxes and tape on connections , but sometimes not- and bare wires are common enough. For whatever reason, death or injury by shock does not appear to be at a detectable level compared to, say, crime or car wrecks etc. I've never heard of an electrical injury in this area, but vehicle accidents are announced daily . I suspect that living in a self-responsible society helps people develop awareness of hazards, although rank stupidity is hardly in short supply here either ! __________________________________

In my case, I am considering running an ac extension in a conduit with the Cat5e for powering an AP on a pole. Too far to extend the DC side of the wall wart. Nobody will ever be anywhere near this plastic conduit and the likeliness of having both the hot and ethernet insulations fail in the exact same point and touch and then have another failure at the connector end such that anybody would touch that is very, very high. More likely to get snake bit standing there !

Though now that I've decided to deploy an old Linksys V4 in this spot, I'm seeing that for $20 I can get a power injector/splitter kit. I wonder if the 12 v power supply will handle 120 feet. I remember Jeff pointing out that they are quite robust and can take a huge drop in voltage...

Let's see, I send 12v * 1A over 120' of 23 ga wire? 5 volts, it appears. But doesn't POE use a pair for each side, so two 23 ga is what, like 18 ga? If so, then 1.5 volts... the linksys could handle it ?


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I did (in the lab); it worked fine.

-- Rich Seifert Networks and Communications Consulting 21885 Bear Creek Way (408) 395-5700 Los Gatos, CA 95033 (408) 228-0803 FAX

Send replies to: usenet at richseifert dot com

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Rich Seifert

yeah - we have warning labels on everything, and lawyers just waiting at the gate....

My s> Very good. This extended dialogue about insurance and such is

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they did last time i had a copy of the IEE regs (a few versions back).

Best practice was to separate mains and low voltage cabling, which is

1 reason you get separation in floor boxes & multi compartment trunking.

the issue here is that Cat5 etc is general purpose low voltage signal cable, and conductors are exposed on RJ connectors so they are easy to touch during changes.

you can get shielded Cat5 - given using it in other environments like chemical plants you should be able to find an equivalent with higher rated insulation, steel wire armour or whatever if you have to do this.....

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Yes, it is an American thing.

NEC = National Electrical Code.

The NEC is produced by the National Fire Protection Association and essentially codifies nationally accepted practices for electrical installations.

While there isn't a single USA wide National code, the states and municipalities that are responsible for inspecting and approving electrical work almost always specify that the work must meet applicable NEC standards.


Reply to
John P. Dearing


You're not the only one to get a chuckle out of Warning Lables.

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Reply to
John Dulak

Code of Practice, not law or regulation.

Sure, but BP isn't the same as regulatory requirement. As much as anything else you don't want some moron electrician cutting the network, or an equally dim network tech frying himself on the mains. In the same way b-p mandates that the upstairs ring runs upstairs and the downstairs one runs downstairs, thus neatly avoiding what I did a few years back - pulling the upstairs ring's fuse and cutting the cable, only to discover my predecessor had run the downstairs loom upstairs. I discovered this, of course, by cutting through the live ring... :-)

That said I can't be a*sed to find my handbooks right now but I don't belive its compulsory to separate them.

Sure, but still tricky to tie onto the /outside/ of underground conduit. There tends to be earth in the way... :-)

Reply to
Mark McIntyre

The ultimate PoE?

It's not the 60Hz, it's the noise, spikes, and glitches on the line that cause problems.

I inherited a customer that had CAT5 running parallel with about 100ft of Romex. That's what happens when you get an electrician to run the residential network wires. They were getting erratic errors on this ethernet connection and were wondering why. I tested it (using SNMP to collect errors and stats) and didn't find anything unusual. However, I did it on a weekend, when nobody was around. During business hours, there was some heavy machinery running on the same AC circuit that was producing large power line glitches, spikes, noise, etc, which were being induced onto the CAT5. Although there was probably no 60Hz coupling, and the common mode rejection should have prevented the glitches from being a problem. That wasn't the case as the distances between the various AC conductors and the CAT3 were different, therefore, different induced voltages.

Incidentally, they also had POTS phone service shared on this run of CAT5. There was 60Hz hum, but only on some instruments.

I'm wondering about the safety issues. Run enough AC and ethernet wires in parallel, and eventually, it becomes a transformer. I'm not sure how much voltage it would induce in unterminated CAT5 wires, but I wouldn't want to find out the hard way. It should be easy enough to test the worst case. Take a length of CAT5 and apply 117VAC to one pair. Measure what appears on the other pairs. Try different lengths.

Reply to
Jeff Liebermann

In comp.dcom.lans.ethernet Jeff Liebermann wrote: (snip)

It is required to run the hot and neutral wires through the same metal conduit for a good reason. If you do, then the net current through the wires should be zero. If not, it will try to induce current into the conduit, or into other wires in the conduit.

-- glen

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glen herrmannsfeldt Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.