RMC across driveway

Todd0x1

Senior Member
Location
CA
Just for the sake of education, whether or not you go with this option, I think it's a discussion worth having.
I assume your two cables would be (1) power and (2) communication.

For the power cable...

Refer to 225.4 and 310.10(C), which address "conductors in cables or raceways" for outside branch circuits and feeders.
Basically it needs to be "rubber covered type or thermoplastic type... and in wet locations, shall comply with 310.10(C)," which lists a few acceptable conductor/cable types for wet locations. You also need an EGC, which is permitted to be bare or covered.

225.6 says "Open Individual Conductors shall NOT be smaller than... #10 AWG Cu / #8 AWG Al for spans up to 50ft... and #8 AWG Cu / #6 AWG Al for longer spans... unless supported by a messenger wire."

I'm not sure about supports for CABLES as 225.6 is explicitly addressing "open individual conductors." I would wager that a messenger wire would be required for your installation, but I don't have a code reference to cite for CABLES in aerial spans.

Does anyone know if the NEC addresses this? There has to be some rules addressing CABLES in aerial spans...

225.18 addresses Clearance for Overhead Conductors and Cables. 12ft for residential driveway.

I think he is just running CAT5 for PoE cameras, no class 1 power involved.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I think he is just running CAT5 for PoE cameras, no class 1 power involved.
Ah ok, I'm not a low voltage guy. Not my strong suite.

I still would like to pose the same question about CABLES in aerial spans though... that has me scratching my head.
Say he was running class 1 power... would it have to be "open individual conductors" twisted around a messenger wire like a service?

I don't see anything in 225 addressing CABLES in aerial spans, just "open individual conductors."
 

Todd0x1

Senior Member
Location
CA
Ah ok, I'm not a low voltage guy. Not my strong suite.

I still would like to pose the same question about CABLES in aerial spans though... that has me scratching my head.
I don;t know much on the subject, but I have seen Tray Cable used in aerial applications supported by a messenger (and anyone doing this better be using metal cable ties or lashing it)
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
As far as the aerial communication cable goes, I can only speculate because I'm not a low voltage sparky. I'll do the typical residential applications (e.g. doorbells, thermostats, landscape lighting, etc.), but here in Chicago, they actually have a separate license for low voltage all together.

I'm curious if the NEC definition of a "branch circuit" would include the communication cable, or if the "branch circuit" would end at the connected device/load such as a router or hub... and the communication circuit would be entirely separate and solely governed by 800... or is there some overlap between 225 (and branch circuits in general) and 800?

Like would the vertical clearances in 225 still apply to communication cables?
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
I would wager a messenger cable would be involved for support, but I can't find any code references in 225 or 800 addressing this.

The only thing I can find in 800 would be Part II 800.44 - Overhead (Aerial) Communication Wires and Cables, which isn't that detailed. It only briefly talks about separating the communication wires from the power conductors (e.g. spanning overhead runs to be located below power and light cables) and a few other brief things such as overhead roof clearances.

It is clear that you can't support communication wires on a branch circuit or feeder service mast or any type of raceway for that matter. So obviously you would need some type of separate means of attachment listed for use w/ communication cables.

As far as the TYPE of cable you would use.. 800.113 addresses communication cable types for various installation methods, but all are inside the building, except for maybe risers mounted vertically on the outside of the building.

I found one post in a different forum suggesting Cat5e STP type that actually came with a built in messenger cable...
1602969398912.png

...but I can't substantiate its' acceptability with a code reference. You could also try searching "Aerial Cat 5e Cable." I got a few results, but again, I don't have any code references to substantiate what type of cable needs to be used.

There is also 800.173 Drop Wire and Cable, which talks about it "running from the last outdoor support to the primary protector" and being "listed as being suitable for the purpose."

Seems that being "listed and suitable for the purpose" would be your requirement, as with a lot of things in this trade.
 

Todd0x1

Senior Member
Location
CA
Dumb question, but this is Class 2 wiring on a house. Can't you pretty much run that anywhere however you want?
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Dumb question, but this is Class 2 wiring on a house. Can't you pretty much run that anywhere however you want?
Not dumb. No such thing. If there was such a thing, I would have been booted from the forum a long time ago, lol.

600.33(A)(3) Wet Locations. Class 2 cable used in a wet location shall be listed and marked suitable for use in a wet location. So technically, this would apply to cable run in the conduit too.
 
Location
Portland
Occupation
Security camera installer
How long is the run across the gate location where you need to underground?
The distance is about 59' from the side of the building where it starts, to the end of the driveway. The remaining 190' is along the fence and could be left above ground.

@Jerramundi. Would you be able to tag that other forum you found that cable? It is likely that I'll either go across the driveway with the vehicle ramp or bite the bullet and go aerially. There is another 10' section that I have to do that anyway so might just do it twice...

Thanks again, everyone! Sticking to reading the whole discussion, so if anyone has any more input, I'm open! :D
 

oldsparky52

Senior Member
If you have cable rated for direct bury, and if you have a concrete driveway you could cut a groove in the concrete (actually have someone else do it if necessary) then sandwich your cable between layers of backer rod and cover with SL-1 .

I doubt this would be code compliant, but it gets you across the road. With low traffic expectations I doubt the cable would be damaged. We used to do this for tank monitoring at gas stations. Works well in concrete, does not work in asphalt.
 

jusme123

Senior Member
Location
NY
Occupation
JW
The distance is about 59' from the side of the building where it starts, to the end of the driveway. The remaining 190' is along the fence and could be left above ground.

@Jerramundi. Would you be able to tag that other forum you found that cable? It is likely that I'll either go across the driveway with the vehicle ramp or bite the bullet and go aerially. There is another 10' section that I have to do that anyway so might just do it twice...

Thanks again, everyone! Sticking to reading the whole discussion, so if anyone has any more input, I'm open! :D
Do you want to be remembered as a DIY or professional?

#1. A DIY would run conduit across the top of a residential driveway.

#2. A professional would saw cut the driveway and bury the conduit at the code prescribed depth.

Stop trying to get this sites permission to do something half assed.

The choice is yours, #1 or #2
 
Location
Portland
Occupation
Security camera installer
Do you want to be remembered as a DIY or professional?

#1. A DIY would run conduit across the top of a residential driveway.

#2. A professional would saw cut the driveway and bury the conduit at the code prescribed depth.

Stop trying to get this sites permission to do something half assed.

The choice is yours, #1 or #2
There is nothing "half assed" about what I'm trying to accomplish. I have done extensive research outside the bounds of this site, but was looking for other professional advice. I am new to RMC conduit, but have been running cable on smaller projects for some time. This project is one of the largest I've ever done, and of course I want to be "remembered as a professional."

I should clarify, this is not a residential driveway. It is for a car lot where they sell hundreds of cars. The area that the conduit would be theoretically run atop the driveway would be by a locked gate that hasn't been used in 11 years, but they would like to maintain it's ability to be used if necessary.

I don't feel it is necessary to describe why I don't want to dig the conduit but that's why I'm here, to discover more options than only one person--myself--could originally think of that would also be professional, to code jobs.

I found the cable I was looking for with a messenger wire and should be able to get this job done going aerial, diagonally from the house to the light pole I need to reach. Is there anything "DIY" or derogatory you'd like to throw my way about going that direction?

I would like to keep everything 100% code.

Thanks again for the feedback!



Dillon
 
Last edited:

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Dillon,

When you do this, I'd appreciate it if you share links to the materials and techniques you use for properly mounting this run.

It seems that the messenger in this cable is very small (1.3mm steel) but most of the clamping hardware is made for much thicker messenger cables.

Thanks
Jon
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Do you want to be remembered as a DIY or professional?
#1. A DIY would run conduit across the top of a residential driveway.
#2. A professional would saw cut the driveway and bury the conduit at the code prescribed depth.
Not necessarily. It really depends on how he installs it across the driveway, if he so chooses to do so.
I would argue, if done well and considering all relevant code requirements, it's still a professional solution.

I agree that it's not the typical solution, nor the preferred solution, but It's the customer's money, not his.

I agree he should advocate for what you're saying, but if the customer simply can't afford it and insists on saving the money to cut and repair the driveway surface, doing it well is still a professional solution.

A DIY solution would be running a cable across the driveway without any protection.

@vaughnethernet Compose a few options for the customer, from high to low, present them to him/her professionally, advocate for the most professional solution, which I agree would be an underground run, but ultimately leave it up to them. You're job is to ensure that whatever method is chosen, is done correctly.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
When you do this, I'd appreciate it if you share links to the materials and techniques you use for properly mounting this run.
It seems that the messenger in this cable is very small (1.3mm steel) but most of the clamping hardware is made for much thicker messenger cables.
Yeah, you don't necessarily have to do the built in messenger cable. I was just giving an example... and as I said, I'm not entirely sure if it's appropriate. You can use an external messenger wire too sized to fit the appropriate hardware as Winnie has said.

The most important thing is that the cable is listed for the purpose. You should be looking for (1) Wet location rated, (2) UV Resistance, and (3) Some mention of it being approved to be run aerially.

Also, sounds by the length of the run, that you should be thinking about voltage drop too.
 

tom baker

First Chief Moderator
Staff member
If this is a Cat 5E application the rules are in Art 720 or Chapter 8 (not 225.18). Since its low voltage, I would suggest sawcutting a kerf, insert the cable, stuff some backer rod in the cut and seal with polyurethane caulk (just l like a loop at traffic signals) Unless there is a local ordnance, there is no burial depth requirement for low voltage.
You can rent a saw cutter or may be easier to have it done.
You will obviously need a direct burial rated cable. Belden makes it, for one.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
there is no burial depth requirement for low voltage.
Not to nit pick, but I'm wondering if you mean "communication circuits?"

I honestly haven't read all of 800 yet 😔 Mostly because it's an atypical installation for me. So I wouldn't know if there's anything in there regarding burial depth requirements... but there are definitely SOME "low voltage" burial depth requirements in 300.5. I believe column 5? But that's only irrigation and landscape lighting.
 

Jerramundi

Senior Member
Location
Chicago
Occupation
Licensed Residential Electrician
Yes, 90.4 tells us the rules in chapter 8 are not subject to the rules in Chptrs 1-7, unless otherwise noted. There is little fire and shock hazard.
Disclaimer, not sure if being POE changes any of this.
I was wondering if there was some overlap... but 90.4 is "Enforcement" in my 2014 Handbook.
Where do you get this from? Is it a 17-20 change? JW
 
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