Conduits inside Conduit

Grouch1980

Grouch1980

Senior Member
Location
New York, NY
I have several conduits that will feed EV dispensers. One conduit contains AC wiring, the other contains communications wiring, and another contains DC wiring. It is being proposed to place all the conduits inside one large RGS conduit, for aesthetics.. this large RGS conduit will house all the conduits I mentioned above. Is there any code or technical issue with this?
 
Sounds odd, Seems one you would run up into total derating based on number of current carrying conductors in a raceway (one reason for derating is ability for heat dissipation) technically all the conductor are in a single raceway. At times there are minimum spacing of conduit runs, Can that be maintained?

Questions to consider: are AC and DC allowed in the same raceway, and under what conditions? Are Low voltage allowed within the same raceway as either of the other 2 and under what conditions? Will the Proximity of each cause some "choking effect" on each other, with associated problems of such? (heating, low data transfer speed or corruption)

I would think there would be a potential for disruption or complications might be issue with the communication cable in close proximity to potential mag field produced withing the common raceway. Their are times that communication cables are to be kept a minimum distance form current carrying conductors.
 
If all three conduits were run in the same wall cavity, would there be a problem?

What about if they were right next to each other and the wall cavity were filled with insulation?

Some of the points raised by @Fred B are potentially important design considerations, but I see no code prohibition.

If conductors are properly installed as balanced circuits, I don't believe magnetic fields will be an issue. Shared heating is my biggest concern.

Have you considered something like
 
Grouch1980 said:
I have several conduits that will feed EV dispensers. One conduit contains AC wiring, the other contains communications wiring, and another contains DC wiring. It is being proposed to place all the conduits inside one large RGS conduit, for aesthetics.. this large RGS conduit will house all the conduits I mentioned above. Is there any code or technical issue with this?
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I think if you put them in one big conduit you can separate the various voltages with Smurf tubing or inner duct. I am not sure separation between AC and DC is even required unless the DC is limited energy
 
petersonra said:
I think if you put them in one big conduit you can separate the various voltages with Smurf tubing or inner duct. I am not sure separation between AC and DC is even required unless the DC is limited energy
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Would that be necessary though? As Winnie said in Post #4... is there any difference running them all inside one large conduit, or within a wall cavity?
 
Is this being proposed for the entire length of the run, or just a portion (maybe where the 3 individual pipes come out of the ground?)
If there are any bends, you can’t nest them!
If it’s only for a portion of the run, it’s just a protective sleeve.
 
retirede said:
Is this being proposed for the entire length of the run, or just a portion (maybe where the 3 individual pipes come out of the ground?)
If there are any bends, you can’t nest them!
If it’s only for a portion of the run, it’s just a protective sleeve.
Click to expand...
it's almost for the entire run... figure 50 to 80 feet.
 
It is common for utilities. You are most likely talking about innerduct. Flex non metallic either corragated or smooth. It is not just aesthetics but also to meet 300.3 where inspectors are picky about insulations.

This way you can use whatever communication cable, DC 2000V cable and 600V THWN.
 
Elect117 said:
It is common for utilities. You are most likely talking about innerduct. Flex non metallic either corragated or smooth. It is not just aesthetics but also to meet 300.3 where inspectors are picky about insulations.

This way you can use whatever communication cable, DC 2000V cable and 600V THWN.
Click to expand...
I've never specified innerduct, so this would be a first for me.
Is this it?: https://innerduct.com/corrugated/

How does this work? The AC wiring would go in its own innerduct (instead of conduit), the DC in its own, and the communications wiring in its own innerduct as well? And then all 3 corrugated innerducts would be installed inside the large conduit? So this would eliminate all the small conduits, now replaced by innerduct?
 
Grouch1980 said:
I've never specified innerduct, so this would be a first for me.
Is this it?: https://innerduct.com/corrugated/

How does this work? The AC wiring would go in its own innerduct (instead of conduit), the DC in its own, and the communications wiring in its own innerduct as well? And then all 3 corrugated innerducts would be installed inside the large conduit? So this would eliminate all the small conduits, now replaced by innerduct?
Click to expand...
Not all innerduct is rated for high voltage (120V+), Some only for communication of CAT cable, So be careful of that product to use within its listing.
Some is HDPE, Restricted by requirements of 353. Some are PVC listed as ENT, and installation must meet requirements of 362.
 
Fred B said:
Not all innerduct is rated for high voltage (120V+), Some only for communication of CAT cable, So be careful of that product to use within its listing.
Some is HDPE, Restricted by requirements of 353. Some are PVC listed as ENT, and installation must meet requirements of 362.
Click to expand...
Is there an innerduct for high voltage?
 
Grouch1980 said:
I've never specified innerduct, so this would be a first for me.
Is this it?: https://innerduct.com/corrugated/

How does this work? The AC wiring would go in its own innerduct (instead of conduit), the DC in its own, and the communications wiring in its own innerduct as well? And then all 3 corrugated innerducts would be installed inside the large conduit? So this would eliminate all the small conduits, now replaced by innerduct?
Click to expand...
And how does innerduct alleviate overheating issues? is it the material, since it's lighter than conduit?
 
Fred B said:
Not all innerduct is rated for high voltage (120V+), Some only for communication of CAT cable, So be careful of that product to use within its listing.
Some is HDPE, Restricted by requirements of 353. Some are PVC listed as ENT, and installation must meet requirements of 362.
Click to expand...
I follow now. Apologies, this is the first time I come across doing this. HDPE conduit IS considered innerduct, for high voltage wiring. And innerduct such as this: https://innerduct.com/corrugated/, is for communication cables. So the recommendation is, use HDPE conduit for high voltage wires, innerduct for communications wiring, and place these inside the large RGS conduit. Do I have this correct?
 
Fred B said:
Not all innerduct is rated for high voltage (120V+), Some only for communication of CAT cable, So be careful of that product to use within its listing.
Some is HDPE, Restricted by requirements of 353. Some are PVC listed as ENT, and installation must meet requirements of 362.
Click to expand...
So if I use ENT for the power wiring (since we're inside a building I cannot use HDPE), innerduct for the communication wiring, and have them inside a large RGS conduit, the installation is now easier and the overheating issue is lessened? As I mentioned, I've never had to do this, this is a first for me.
 
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