Shielding 22/4 along with HJV in a single conduit

[snakevargas]

I have a shed, about 40ft away that I'd like to run both a 120 VAC circuit and some shielded 22/4 for my elk sensors. The conduit run unfortunately has to be visible above ground, so I'd like to make it a attractive as possible. So, the questions:

1) Is it code-legal to run LV and HV together in a single conduit? I'm guessing probably not.

2) Assuming one did it anyway, would there be sufficient interference from the 120 VAC to prevent the sensors from working? We're talking standard door contacts.

3) How about Elk RS-485 for an expander?

I really don't want to have to run two conduits, but I suppose I will if I must.

Oh, and the title should have said "shielded", not "shielding".

 

[pete_c]

The conduit run unfortunately has to be visible above ground,

Is it because of a driveway or cement?
 
You can still just put a connection(s) up high on your home to the top of your shed; thinking that is legal still?

 

[pct88]

Is the LV/HV restriction based on the voltage running through the wire or the voltage RATING of the insulation?  I know it is a special case, but the cable bundles run to elevator cars have a range of voltages from 120v for lights and door motors to low voltage for call buttons and displays, telephone lines for the emergency telephone, etc... all in a single bundle.  If the issue is just the voltage rating class of the insulation can he run additional conductors with adequately rated insulation for the sensors and extend them to a LV specific junction box at each end?

 

[snakevargas]

 

Is it because of a driveway or cement?

Sort of in between. It's a paved RV parking area. The cement runs all the to the foundation of the house, so there's no way to get under it short of using a jackhammer or cement saw.

I don't think I want to string them through the air, either.

 

[pete_c]

In the old house I had a fence up along the cement driveway between the house and the garage. 
 
I put in the garage and ran LV and HV conduit along the fence line underground. 
 
Is there any way to go around the cement to either side of the house?
 
Posting a satellite picture showing the area you are writing about would help maybe.

 

[snakevargas]

 

Is there any way to go around the cement to either side of the house?
 

 

The RV parking area extends to a concrete patio that runs the length of the back of the house. I could go that route, but would add about 150 feet to the run (and end up on the opposite side of the house from where the ELK panel and main breaker panel are located).

They've almost surrounded this house with concrete. I'll see if I can dig up a photo.

 

[pete_c]

150 feet is not too bad. 
 
Thinking you mentioned already going into the crawl space; such that you are already family with what is down there; eh?

 

[snakevargas]

150 feet is not too bad. 
 
Thinking you mentioned already going into the crawl space; such that you are already family with what is down there; eh?

Familiar enough to hate it! Parts of the crawlspace are fine and quite spacious, but parts are also too narrow for me to fit. This unfortunately would traverse through the narrow spot.

Anyhow, I've already made the decision to go the over-concrete route for the 120VAC. One conduit really doesn't look so bad because I can hide part of it under a lip in the retaining wall. It's adding the second conduit that will be the issue.

 

[Del91574]

1. Yes, but only if the cabling shares the same voltage rating on the insulation, then it must be separated as soon as it leaves the conduit. Lots of other caveats to boot.
 
2. Maybe, you can never test or account for inductance.
 
3. Asking for problems running 485 next to HV and possible inductance.

 

[RAL]

Overall, I think running these in the same conduit is a bad idea, and may violate the electrical code.
 
One part of the code states:
 
725.136 Separation from Electric Light, Power, Class 1,
Non–Power-Limited Fire Alarm Circuit Conductors, and Medium-Power Network-Powered Broadband
Communications Cables.

(A) General. Cables and conductors of Class 2 and Class 3 circuits shall not be placed in any
cable, cable tray, compartment, enclosure, manhole, outlet box, device box, race- way, or similar
fitting with conductors of electric light, power, Class 1, non–power-limited fire alarm circuits,
and medium-power network-powered broadband communications circuits unless permitted by 725.136(B) through (I).
 
As DEL pointed out, there are circumstances where is may be allowed,  From what I have read about
this on other web sites, at a minimum, you would have to use wire for the alarm contacts that has the
same 600V (or higher) insulation rating as the 120V circuit.   You probably won't find that on 18 or
22 gauge alarm wire.  So you would have to run the alarm circuit on 14-2 as well.  Using 14-2 would present
you with the problem of how to properly shield those wires from the 120V circuit.

 

[tmbrown97]

For what it's worth, you can just run shielded outdoor cat5 strapped to the conduit up in the back inside corner where it's totally hidden - you don't have to run it in a large piece of conduit of its own.

 

[Del91574]

@ RAL
Yes, that is part of the equation. There are LV cables that are rated for 1000V/600V...etc. You can buy them, but with conduit outside, now you're looking at a W suffix cable also. I'm being slightly lazy to drag out my code book where I am, but it is possible to do and is frequently used as a "gotcha" example for tests and training. The other item to consider is induced current, but in the case of a contact, you can ground, use ferrites as chokes and also optically isolate the cable, but generally you'd need to look at the cost and effort involved in doing such compared to a trench, saw cut, etc.

 

[tmbrown97]

How many sensors are we talking about here?
 
Another option is to use a wireless technology to bridge the gap - it'd cost you about $500 for a 4-channel setup, but it's a highly reliable system and doesn't require other wireless infrastructure in your panel - it'd convert 4 wired contacts in the shed to wireless then back to hard-wired at the alarm panel.
 
Or at 40' you might be fine with Elk's 2-way depending on where the receiver mounts...
 
Lots of ways to accomplish the goal.
 
If you still want to go conduit, are you talking about only being able to hide PVC, and if so, what size?  You could get fairly small metal conduit to protect Cat5 from tampering if so desired as well... just have to make sure do the electrical portion to code.

 

[Del91574]

40', barring a steel constructed building or foil insulation, not a problem for any of the RF the M1 supports.
 
I'm not a huge cheerleader of Elk's own RF, the pro's don't outweigh the cons in my applications, YMMV.
 
Smallest conduit is still 1/2" trade size (PVC has larger OD). Assuming DIY, metal with compressions is not very friendly for a DIY. Rigid, forget it.

 

[snakevargas]

Only two sensors. One will be for a traditional door. The other is a roll up door. In a perfect world I might also install a motion sensor or even a keypad, but those would be far off into the future.

I do have elk ge wireless already for hard to wire places in the house, so using that is an option. I'd prefer wired for the reliability and reduced maintenance. I might go with attaching the cable to the outside of the conduit, as suggested.