Mixed voltages in a conduit

I know that you are not allowed to mix, say a low voltage line in a conduit with line voltage wires. My question is, can you mix them if either the line voltage wires or the low voltage wires are in their own "conduit" inside of the larger conduit? I have a 2" diameter plastic, flexi conduit going from my house to an area out by the road. Right now it is used to bring 120 volts to a post lamp and an outlet in its base. Now, if I wanted to run some low voltage lines, could I put them in a piece of Greenfield (grounded of course) and run that Greenfield with its low voltage wires, through the same conduit?
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Would think so -- seems like it would be similar to Wiremold 5000 where line voltage and low voltage wires are in the same enclosure but separated by a physical barrier so they can't touch each other.
Tomsic
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On 4/12/2013 5:57 PM, Art Todesco wrote:

I've run low voltage control cable in the same conduit as the power supply but it had insulation that matched the voltage rating of the power cable. It really depends on the folks who have jurisdiction over the inspection of the job. I've done work where The Army Corps of Engineers was the inspection authority and sometimes they are much stricter than what the NEC calls for. o_O
TDD
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Art Todesco wrote:

I'd certainly think so. Innerduct is common enough inside a larger conduit, and I don't know of anything in the NEC that cares about anything beyond the conduit enclosing a particular wiring. If wiring x is good inside conduit x it shouldn't matter if the whole thing is in larger conduit y as long as the conduit y fill specs are ok.
My normal recommendation is that when someone is running conduit they run extra for potential future uses since conduit is cheap, particularly PVC conduit. In a case like yours I would have suggested parallel runs of 3/4" PVC conduit for just such future cameras, intercoms, gate operator controls or whatever.
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wrote:

"raceway" Can't use NMD (or metallic sheathed either) cable in a conduit, but I believe it is acceptable in a raceway. Cables of different voltages are allowed in a raceway. Wires of different voltages must be segregated in a raceway. Wires of different voltages are not allowed in a conduit. Can a "conduit" be used as a "raceway"???
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On Fri, 12 Apr 2013 19:44:58 -0400, snipped-for-privacy@snyder.on.ca wrote:

A conduit is a raceway, You are thinking about a duct. Conduit is just one type of raceway.

The difference is a raceway terminates at both ends in a box or enclosure. A duct is usually open at both ends. There are actually ways to run a line voltage and a low voltage "cable" in the same conduit/raceway but they must be split out and terminate in different enclosures.
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On 4/12/2013 10:10 PM, snipped-for-privacy@aol.com wrote:

Power wires of different voltages can be run in a conduit, which is a raceway.

If the OP is running "class 2" wiring (as used for doorbells, thermostats,...) the wires can be run together if "Either (a) all the ...power... conductors or (b) all of the Class 2 ... circuit conductors are in a racway, ... or Type UF cables." (725.136-I-1).
The OP is not specific what "low voltage lines" are, or how many. If class 2, running either the power or the class 2 as UF cable would work. If you run one of them in a raceway I would suggest plastic ENT instead of Greenfield.
If it is going to be inspected, I would run the plan past the inspector.
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wrote:

I agree about asking the inspector. The code says cable jackets are separation but the rub usually comes in when you terminate the cables. If you can split them out of the raceway system into separate enclosures before you crack into the jacket, it is legal but a lot of inspectors will still fail it. I have seen this done with "T" body condulets on both ends. Usually it is simply easier to run separate conduits.
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On Apr 13, 11:09 am, snipped-for-privacy@aol.com wrote:

Seems like the easiest solution is to run a 14 gauge cable in the same tube/pipe/raceway/conduit as the power cable, then you can do anything you want with the extra cable, whatever the local codes require/
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On Friday, April 12, 2013 3:57:26 PM UTC-7, Art Todesco wrote:

Someone correct me if I’m wrong but I don’t think Flexible Nonmetallic Tubing is suitable for direct burial let alone used over six feet if I know my NEC.
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On 4/12/2013 6:57 PM, Art Todesco wrote:

Thanks to all who replied. Some of my questions were curiosity based on stuff that I am or will be working on. I do have a 2" plastic conduit which presently has 120 volt UF cable in it for the said post lamp. Other low voltage things might be a speaker line or 12 volts for landscape lighting.
In addition, my subdivision has a gate at the entrance. The gate controller has the ability to allow a visitor to look up each resident and call the resident. The resident can, via phone keypad, open the gate. Right now there is no phone line connected to the gate controller. However, there is a phone line about 30' from the gate controller, which is owned by me, but it must cross the asphalt. There is a 3" (I think) conduit under the asphalt. The possibility is run the phone line through that conduit to the gate controller. There are 120 or 240 volt lines in the conduit. So, the phone line should probably be run using an ENT or equivalent, inside the original 3" conduit.
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On 4/14/2013 7:13 AM, Art Todesco wrote:

You could pull MC cable through the PVC which would put your power in essentially a metal conduit inside the PVC separating low voltage and communication lines from the power. ^_^
TDD
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On Sun, 14 Apr 2013 09:46:03 -0500, The Daring Dufas

Legally, cables are cables. For the purposes of this, UF is the same as MC. The main issue is how you get these cables into and out of the conduit without getting into the jacket. Neither can terminate in an enclosure with the other. That is why inspectors usually just say no. The option most likely to survive is simply a sleeve that is not ending on an enclosure at each end. Then the cables just use that as a duct. Discrete conductors would need to be in a flexible raceway of some type. (Greenfield, Sealtite or Smurf) IMHO If you have a box or conduit body at both ends where the cables split out as undisturbed cable and terminate in separate boxes, you are OK Another option would be one big box, partitioned into 3 separate areas, one for the entrance of the cables, where they split out and a separate area on each side where low and line voltage get terminated.
All that said, there are still plenty of inspectors who will not accept 725 (low voltage) wiring in the same pipe as chapter 3 (line voltage) wiring, no matter how you do it.
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On 4/14/2013 10:22 AM, snipped-for-privacy@aol.com wrote:

I suppose it would all depend on the engineering department in your jurisdiction? I've done work for The Army Corps of Engineers and if we approached them with a problem that seemed like it was outside normal practice, they would allow our solution if they deemed it safe. o_O
TDD
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On 4/14/2013 12:57 PM, The Daring Dufas wrote:

flex plastic stuff, inside the larger conduit, should work. Where the large conduit terminates at a box, the flex plastic could just go into the box and out through a hole, thus keeping it fully segregated.
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On 4/15/2013 7:14 AM, Art Todesco wrote:

I did mention the low voltage cable having a voltage rating on par with the higher voltage cable. Most low voltage cable I work with has 300 volt insulation when most house wiring in The U.S. has insulation rated for 600 volts. There is also the problem of inductive pickup from power cable to low voltage cable. Many years ago, I worked in the burglar alarm industry and I tried my best to get the owner not to run the alarm lines along with the Romex power cable in homes. Whenever lightning struck close by, there was an inductive coupling to the low voltage alarm wires and the alarm panel often got zapped. Even though there were MOV's on the circuit board, the darn things would explode with the first strike and the IC chips would blow off the circuit board by the second strike. I often run shielded low voltage cable if it's going to be run in close proximity to power cable but if installing something new, MC cable run for the power is less expensive than finding shielded low voltage cable for a particular section. If I'm running PVC electrical conduit underground to an out building and there needs to be an extension of the alarm system, a remote control or POTS line, I'll pull MC cable for the power and not worry about the low voltage cable in the same conduit. On the other hand, if I'm going to pull a 4 wire 100amp circuit in a large underground conduit and wish to share the space with a low voltage circuit or two, I'll pull in some flexible metal conduit to put the low voltage cable in. I always have a pull string in there too. ^_^
TDD
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On 4/14/2013 10:46 AM, The Daring Dufas wrote:

telephone central office. They had always mixed cables in the rack. There were large (like your thumb) cables for DC power, MC cables for AC power and also a lot of multipair telephone type cables. Apparently, while removing cables from the rack, the MC cable wore the insulation from one of the DC power cables and caused the fire. Even though the damage was confined relatively small area, it knocked out communications in a very large area for a relatively long time. After that, they were going to segregate the cable types.
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On 4/15/2013 7:08 AM, Art Todesco wrote:

Somebody wasn't paying attention when the wire was being removed. There have been many explosive events when someone decided to yank out wire from an energized system. I've also worked high voltage underground power in the 4,160 volt range and even though that's one of the lower distribution voltages it's still extremely dangerous to the un-careful. ^_^
TDD
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On Apr 15, 7:53 am, The Daring Dufas <the-daring-du...@stinky- finger.net> wrote:

It's hard to power down a teleohone office to move cables, so we always did it live,
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On 4/15/2013 10:33 AM, snipped-for-privacy@sbcglobal.net wrote:

I realize that and most folks have no clue as to the DC power and size of the battery banks and power supplies it takes to run a central office. I don't have as much experience with switches as I'd like but the last one I fooled around with was a Dimension 2000 which replaced what was said to be a more reliable crossbar switch on an island where the missile test range was where I worked for a while. o_O
TDD
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