Would Non Metallic Liquidtight be better a better choice than PVC Conduit for this application?

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We need to run some LTE Antenna cable up to the roof for 3 LTE Antenna's.
We were thinking of using Schedule 80 PVC . to avoid cracking due to exposure to the hot sun.
I got to wondering whether the long lateral runs would need expansion fittings.
Then I started thinking about other ideas besides PV C conduit, since PVC fittings doesn't always behave in the sun.
Would Non Metallic Liquidtite be better in this application?
Will it be okay 20 years from now?

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PVC is a poor choice, it requires frequent strapping but the conduit has to be able to move for expansion. You will need expansion couplings on horizontal and vertical runs.

LTNMC would look terrible and you can’t keep it straight.

I would use 2” EMT and LMR 400 coax if the loss is acceptable. The min bending radius for LMR 400 is 2”

Can you install the radio on the roof and run ac power to it, then run fiber to network equipment? Fiber can be run in conduit power

Another option would be galv cable tray, then you could run a larger LMR coax. Cable tray would be similar to cell towers. Your bonding jumper can run in the tray. If you are concerned about vandalism install a cover on the tray, with 3 coax runs the cable tray makes sense

Your polyphaser and antenna mast are required to be bonded at one point to the building ground system. I would put a ground rod below the polyphaser and run a 2awg to the building ground rod, CAD weld all connections.
 
tom baker said:
PVC is a poor choice, it requires frequent strapping but the conduit has to be able to move for expansion. You will need expansion couplings on horizontal and vertical runs.

LTNMC would look terrible and you can’t keep it straight.

I would use 2” EMT and LMR 400 coax if the loss is acceptable. The min bending radius for LMR 400 is 2”

Can you install the radio on the roof and run ac power to it, then run fiber to network equipment? Fiber can be run in conduit power

Another option would be galv cable tray, then you could run a larger LMR coax. Cable tray would be similar to cell towers. Your bonding jumper can run in the tray. If you are concerned about vandalism install a cover on the tray, with 3 coax runs the cable tray makes sense

Your polyphaser and antenna mast are required to be bonded at one point to the building ground system. I would put a ground rod below the polyphaser and run a 2awg to the building ground rod, CAD weld all connections.
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I think the emt would be cheaper too at this point just looking at the LBs and Ts it's worth just going to a 3r box
 
1. Do we need special fittings for Aluminum conduit? Or can we use the same compression couplers and threaded unions, reducers, etc. that we use for EMT, or IMC.?
2. A bundle of 3 LMR-400 cables (.40" each) is 1 inch in diameter. Would it be okay to use 2" conduit with 3 " conduit bodies at the bends to accommodate the LMR 400 bending radius of 4"

run3.PNGrun4.PNGmodate the LMR 400 bending radius
 
I did about 40 antenna installs with LMR 400, 2 RMC mast and T conduit body. I had the check since it’s been a while, but the bend radius of LMR 400 is 1 inch, 4 inches for something that’s moving. Also, the otter diameter is .4 inches, which is why it’s called LMR 400. 2 inch conduit would probably work just fine.
Note I misread your post you have 3 cables.4” and all three are 1” od
 
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I would have to check the code article, but fiberglass conduit would be non-corrosive it’s extremely strong, but I don’t know how it would hold up on the outside of a building. I’ve used it before underground. The inside is like well, glass, and it’s easy to pull through.
 
tom baker said:
I would have to check the code article, but fiberglass conduit would be non-corrosive it’s extremely strong, but I don’t know how it would hold up on the outside of a building. I’ve used it before underground. The inside is like well, glass, and it’s easy to pull through.
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Cost at this size would favor metal I think although that would avoid alot of the expansion joints
 
Installer said:
1. Do we need special fittings for Aluminum conduit? Or can we use the same compression couplers and threaded unions, reducers, etc. that we use for EMT, or IMC.?
2. A bundle of 3 LMR-400 cables (.40" each) is 1 inch in diameter. Would it be okay to use 2" conduit with 3 " conduit bodies at the bends to accommodate the LMR 400 bending radius of 4"

View attachment 2570688View attachment 2570689modate the LMR 400 bending radius
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Should be fine. I would check if TB's are available
 
I've only used LMR-400 in hobby situations, but it strikes me that it will be a pain to route through conduit and conduit bodies, even when bending radius is properly respected. The stuff is not very flexible, and you want to be very careful not to kink it. If you kink an electrical wire, you put its insulation at risk. If you kink a coax you risk both the insulation and the impedance characteristics.

I'd first ask _why_ are you routing a cable designed for outdoor exposure through a conduit?

If this is simply for looks or mechanical protection, I'd consider something the equivalent of an HVAC lineset cover or an electrical cable duct. Possibly in metal since this isn't residential. But specifically something that is an open tray where you can lay the cables and then attach a cover, rather than having to fish cables through a pipe.

-Jonathan
 
winnie said:
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I'd first ask _why_ are you routing a cable designed for outdoor exposure through a conduit?

If this is simply for looks or mechanical protection, I'd consider something the equivalent of an HVAC lineset cover or an electrical cable duct. Possibly in metal since this isn't residential. But specifically something that is an open tray where you can lay the cables and then attach a cover, rather than having to fish cables through a pipe.

-Jonathan
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One of my client's buildings has a cell site on the roof and they put a sheet metal cover over the cables and painted it the color of the building. You hardly notice it.
 
For outdoor work in wet locations I like to paint the metal conduits first even before bending or joining lengths with cold galvanizing spray paint, and then a good coat of exterior sprayed on paint to match the building. Hand touch up on where the bends were made cause always no matter what there will be exposed places at bent pipe where the paint completely came off during the bend.

The conduit will last decades longer after being treated this way. Especially necessary for pipe runs up on the roof to package air handling machinery and the like.
 
"If this is simply for looks or mechanical protection, I'd consider something the equivalent of an HVAC lineset cover or an electrical cable duct."


You're correct. I'm thinking the same thing. Unfortunately its a vendor requirement. I considered 4 x 4 square duct which you always see on rooftop antenna farm but it's not cosmetic at ground level . So then I went to PVC and there was an expansion issue.
They sell LMR 400 to ethernet converters. To get the vendor to buy in on that would take a long time. But then I would have to get power up there and I have a converter housing issue.
 
Installer said:
You're correct. I'm thinking the same thing. Unfortunately its a vendor requirement. I considered 4 x 4 square duct which you always see on rooftop antenna farm but it's not cosmetic at ground level . So then I went to PVC and there was an expansion issue.
They sell LMR 400 to ethernet converters. To get the vendor to buy in on that would take a long time. But then I would have to get power up there and I have a converter housing issue.
Click to expand...

In this case, I would suggest using the conduit only going up the side of the building, and then entering the 4 x 4 square duct at the roof level.
 
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