Wiring a Radio RA2 Auxillary Repeater

I might need to extend a Radio RA2 system to a boathouse that is being renovated so I will need to bury an RS485 cable to connect the Auxillary Repeater. I know Lutron spec is 2 pair if 18 gauge twisted pair with one pair shielded but I am curious why it needs this? Direct bury Cat6 would probably be cheaper and most systems using RS485 communication are fine with 2 pairs of UTP. What is Lutron doing that requires the heavier gauge and shielding on the data pair?

Have you asked on the Lutron forums?

https://forums.lutron.com/forumdisplay.php/32-RadioRA-2

Though, if you're using Ra2 you're already familiar with not having cheaper options.  I'd stick with their recommendations.  
 
A 'sunk cost' pun seems relevant here... 

Not planning to go outside of spec. I was just curious why Lutron needs this.

Cat 5 cable specs match RS485 specs almost exactly with the exception of slightly lower impedance (100 vs 120 ohm). Shielding may be required in noisy industrial applications but is an overkill in home applications.
 
The gauge only matters if the bus is terminated in which case at least 22 is preferable (cat 6A has this gauge).  Do not remember whether the bus is terminated with Lutron.
 
In my previous house, I used a direct burial Cat5 cable over 120' without any issues.
 
https://e2e.ti.com/blogs_/b/analogwire/archive/2016/07/28/rs-485-basics-when-termination-is-necessary-and-how-to-do-it-properly

I don’t know specifics here but if it were me I’d run conduit regardless. Then I suppose you could try the cheaper cable if you’re feeling lucky and if it doesn’t work just pull the proper cable.


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TrojanHorse said:

I don’t know specifics here but if it were me I’d run conduit regardless. Then I suppose you could try the cheaper cable if you’re feeling lucky and if it doesn’t work just pull the proper cable. Sent from my iPhone using Tapatalk

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It's a pretty long run between buildings. I worry with conduit that any pull strings I include with the wire bundle will get so twisted with the other wires that using them to pull a new wire over that distsnce will be impossible.

Existing cables are always pulled out and pulled back in with new conductors included. Too much friction.

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LarrylLix said:

Existing cables are always pulled out and pulled back in with new conductors included. Too much friction. Sent using Tapatalk

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Which I don't like to do. My methodology is to terminate building wiring to a patch panel or block and then never ever touch it again. All changes from that point are between the block or patch panel and whatever equipment is changing. I don't mind wear and tear on cross connect wires or patch cables but I never ever ever disturb permanent wire plant cables again once they have been terminated.

upstatemike said:

Which I don't like to do. My methodology is to terminate building wiring to a patch panel or block and then never ever touch it again. All changes from that point are between the block or patch panel and whatever equipment is changing. I don't mind wear and tear on cross connect wires or patch cables but I never ever ever disturb permanent wire plant cables again once they have been terminated.

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With a few feet of pipe, not bad, but damaging connections and cable jackets may not be what you want. We found it very seldom worked well, but most of the mods were over 100 feet with 4 to 9 conductor #12 AWG cables and some with shields, with later specs. These were mostly 2" to 5' ducts also.  You can stretch the conductors and break insulation. Smaller conductors and pipe are usually worse.

LarrylLix said:

With a few feet of pipe, not bad, but damaging connections and cable jackets may not be what you want. We found it very seldom worked well, but most of the mods were over 100 feet with 4 to 9 conductor #12 AWG cables and some with shields, with later specs. These were mostly 2" to 5' ducts also.  You can stretch the conductors and break insulation. Smaller conductors and pipe are usually worse.

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Probably easier to do direct bury and if they want something new down the road I'll bury a new bundle in a parallel trench. This will probably be a long run between buildings with quite a few twists and turns to avoid existing buried stuff. One end terminates in a basement though... I need to design an entrance solution that doesn't end up piping ground water into the equipment room.

upstatemike said:

Which I don't like to do. My methodology is to terminate building wiring to a patch panel or block and then never ever touch it again. All changes from that point are between the block or patch panel and whatever equipment is changing. I don't mind wear and tear on cross connect wires or patch cables but I never ever ever disturb permanent wire plant cables again once they have been terminated.

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I think Larry's point was if you're going to have conduit and make any changes later the best plan is to PULL OUT any old cables and pull all new.  Not to attempt to pull anything additional through an occupied conduit. 

I support this sentiment with one caveat... if it's a large enough conduit with decent pull boxes points along the way.  For example, a 2" conduit with 3 cables in it.  I wouldn't feel too concerned about adding a fourth.  But a 3/4" with the same three?  Or one long run of 2" with several turns and no pull boxes?  No, as there's too much potential for damaging the existing cables.

As for basements, I never to like to go straight into a wall if there's any chance at all of ground water issues.  Up the structure and then in.  Conduit is useful here to ward off any gardening efforts from later chopping the cable.

I've not kept up on various trenching techniques.  There's been a number of new developments to tunnel cabling through instead of trenching above.  But I've no idea what the costs are like, nor whether options exist that'd work in your area.  I'm guessing central NY has plenty of rocks near the surface, thus likely requiring opening a trench, correct?

It is a boat house on Skaneateles lake. It is solid bedrock with a thin layer of topsoil. Probably just use a Ditch Witch or something similiar.

Hey Mike - not trying to be a bug but a thin layer of top soil would definitely cause me to use conduit. But that’s just me - I would probably run 2 conduits to begin with so you can just ignore me ;-)


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Just got some updated requirements and it looks like there will be a lot more wire in the low voltage bundle than previously identified so I am also leaning towards conduit again... probably a fairly large PVC pipe. The owner also does not like large banks of switches and wants to utilize dual stacked Radio RA models to reduce gang count wherever possible. Since this is an extension of the main house Radio RA system I need to coordinate with the vendor who maintains it and make sure we are on the same page on how the two buildings will be linked and wired.