Yes. No.

You are fine.

I agree with petey. The only issue with mixing the low voltage stuff with the 110 is when one side or the other is outside of it's insulation (i.e., terminated in a box).

No.
Yes.
Check out this link.

Here is a link that might be useful: common mistakes

That link is only partially correct. It can cause interference on data lines but in this case there is nothing to interfere with. The thermostat wire is not a data line and there is no worry about interference.

Indeed. The thermostat circuit is such low impedance that "interference" is just about impossible anyway. The "signal" is simply a switch closure, and is 60Hz AC already. 60Hz AC can't really interfere with 60Hz AC, and the relay contacts in the furnace obviously couldn't move that fast anyway, even if interference were possible.

No, but I'm in Canada. LV/signal wires can share but power should be separate. However, in practice it's probably not too bad.

That's a good little pdf.

Upon reflection, if you can move that wire, or the thermostat wire, you probably should. Just nicer, neater, safer and will give the inspector one less thing to trip you up on.

The wires as you have installed them are fine, there is really no need to move either one of them.

What is being discussed in the link is not the same as the situation described by the OP. There will be no interference issues and since the wire for the light, and the thermostat are not inside of the same box there is nothing wrong with the installation.

What you have done does not violate any code.

That .pdf is OK, but VERY reactionary. Stating that a low voltage and line voltage sharing the same hole can cause a fire is scare tactics plain and simple. The story they tell about the carpenter driving a 16p nail through the NM cable and then through the t-stat cable WAS the carpenter's fault.

I HATE examples like that .pdf that use opinion and dramatics to convey and opinion as opposed to stating FACT about something.

Would I run data/CATV and line voltage through the same hole for long distances, no.
Would I do what the OP did, absolutely.

BTW - I would not use Taunton Press as an acurate source of electrical facts. They had a recent recalls of a DIY wiring book that was riddled with inaccuracies and dangerous advice.
I would take ANYTHING they print with a grain of salt.

Here is a link that might be useful: Taunton Press Recall

Sorry, the last link was not direct. Here is the real one.

Here is a link that might be useful: Taunton Press Recall

Fine Woodworking (also from Taunton press) got burned by a university professor answering a question about running table saw motors on 240 V vs. 120 V.

He gave the professorial answer of 'no difference.'
His answer was correct only if the voltages at the motor terminals are the nominal values.
He completely neglecting the decreased voltage drop in the lines supplying a 240 V motor.
Reality bites back sometimes.

Most of the rules in the NEC cover having low voltage and high voltage in the same box.
A barrier is required unless the low voltage rating insulation is high enough.

It is extremely important that we note a difference here.

There IS an issue with putting LV and 120 IN THE SAME BOX: Insulation ratings, and the fear of the electricity from one getting conducted into the other (accidentally, of course)

There IS a totally DIFFERENT issue with running "low-power signals" - electronic data in analog or digital form - parallel to AC power over long spans. In this case, induction can occur between the lines and the 60Hz from the power can get mixed in with the signal and confuse the sensitive electronics on the receiving end.

There IS NOT an issue with wires happening to pass through the same hole in a 2x4.

There is also NOT an issue with LV ANYTHING and power crossing at a 90-degree angle.

Further, the relay on the furnace end of a thermostat wire is NOWHERE NEAR sensitive enough to react to any current induced from a parallel run of AC power.

In no way, shape, or form, does a thermostat cable and an AC power wire running through the same hole in your framing constitute a problem of any electrical or electronic nature.

Sorry Dawg, you are wrong.
A bored hole in framing is NOT a raceway, enclosure or manhole. What's a "wormhole" BTW???
And your example, obviously drawn from that article, is NOT a typical scenario. If the proper spacing and clearances are met, such as the 1-1/4" setback from the edge of framing, this should not be an issue.

I suggest you read up a little better on the codes you are using to support your opinion.

The NEC 2008 does not have Article 725.55. The closest Article in the NEC 2008 to the one referenced by dawger is 725.48. No mention of holes of any type.

Lots of times we will rough in before the HVAC is complete, ie just the ducts will be there. Then when they put in the rest, they always just poke their t stat wire thru one of OUR holes.

On the last job, the LV guy got there after us and ran nearly all his CATV, phone and speaker wires thru our holes, right alongside our romex, for many feet. The alarm guys did the same thing.

I don't see a problem with the stat wire, but the other stuff is just plain LAZY. It is time for those installers to go look for another field of work and let someone who takes a little pride in what they do take their jobs.

All irrelevant and non-existent codes references aside the bottom line of this entire thread is this:

OP, to answer your question - Yes, what you did is fine and will not cause any problems!!

I know others have already said the same thing but it seems to have been lost with discussions of fires, and dual use boxes, and phantom code references...

You're right Bus. I forgot to mention that. It was changed for 2008.

petey_racerSorry Dawg, you are wrong.
A bored hole in framing is NOT a raceway, enclosure or manhole. What's a "wormhole" BTW???

It's for when you need to install a thermostat in the far reaches of space...

Zone 1: DOM HW
Zone 2: Downstairs
Zone 3: Upstairs
Zone 4: Alternate Dimension

LOL! Seriously. :D

Hey, what code did you use to make that quote?

It's an html table with bgcolor.

<table width=100% border=0 cellborder=0 cellpadding=0 cellspacing=0gt;<tr><td bgcolor=7f7f7f><b>Quoted Poster's Name</b><tr><td bgcolor=bfbfbf><em>Quoted Text</em></tr></table>

Ok ya got me. I have an older code book and I used "wormhole" to describe the hole in the top plate. Its actually 725.55(J)Other Applications, that says the wires need to be at least 2" apart from each other(unless you want to interpret the insulation on the thermostat wiring as non metallic sheathed). I know what he did is common practice but I was called on it once by the fire inspector and had to move it.

There is the aspect of derating with multiple wires.

When I was installing/roughing in alarms, I was instructed in no uncertain terms we were to make our own holes and not double up with anything, and at least in Canada, power/ac (inc doorbells etc) and data/lv couldn't be mixed, although comms could mix with security wiring for example.

This pertains to Canadian rules and telephone specifically, but it says (quoting Telus literature) "The Canadian electrical code Part 1, rule#60-300 requires a minimum of 50mm (2") separation from power cables." It also goes on (not quoted as part of the code afaik) the wires should not run parallel to power cables within the same stud space, nor be pulled through holes occupied by electrical cables.

Oddly, my BC electrical codes (simplified) doesn't refer to this rule at all.

Well the thermostat wire is definitely "non-metallic", and it is definitely "sheathed". :P

Canadian code, eh? I'm not quite THAT far North.

Not running telephone wires parallel to power cables is one of those aforementioned interference/induction issues. I don't know anything about Canada, but here, that's a recommendation, not a requirement.

And what is a stud space, if it isn't a big hole?

dawger, I'd like to see a screenshot or scan of your NEC, because my 2008 copy doesn't HAVE a 725.55.

Hmm ok, if an electrical wire (and, by extension, lv or communications wire, according to my boss) is run across a hw pipe or hvac heating duct (I've always assumed a cold air return was exempt but I always insulated the wire in case of vibration, you don't want noise or insulation wear) we are instructed to cushion or insulate the wire with a piece of fibreglass insulation or similar - I assume that applies in the US code?

The US code has a blanket statement that things must be protected from physical damage. It doesn't state exactly what that entails but I really doubt that "a peice of insulation" will pass the muster by most AHJs

"Not running telephone wires parallel to power cables is one of those aforementioned interference/induction issues."

You really have to work to get 60 cycle hum into a phone line.
The handset has a lot of filtering to remove the inevitable 60 Hz noise (and its 120 Hz harmonic).

Communications cables are reasonably resistant to 60 Hz interference.
You really have to couple a lot before the input amplifiers start getting saturated and cannot reject the noise since it appears as common mode (equal on both wires) on twisted pairs.

I found the following by google:

http://www.nfpa.org/assets/files/PDF/ROP/NEC2008Article705-800.pdf

Looks like it has 2008 NEC dawger talks about. It has 725.55

per08, the 2008 NEC does NOT have a 725.55
The 2005 NEC does.

My bad. I was wrong, wrong, wrong. So was that inspector. Not that I'd have argued anyway. It actually says as long as one of the wires,(class 1 or class 2 is sheathed),its OK.
This is a link to a copy of 02 NEC which is the same as the 05 NEC I was using. In the 08 its 725.136(I)(1). Sorry per08, but its better to err on the side of safety.

Here is a link that might be useful: 2002 NEC

I've always understood that the prohibition against combining LV and line pertained to individual conductors in the same raceway. But if either/or is in a sheathed cable, the sheath effectively constitutes its own raceway, and therefore meets the requirement of The Code.

True?

No idea if code/law would ever make such a distinction, gblentz, but that's an accurate summary of how my brain perceives it, and why I fail to see any problem with them running together.