Minimum distance between hv and lv?

[DrunkenLizard]

Whats the minimum distance I would want to run a conduit for low voltage from some high voltage wires?
I'm rather limited on the locations I can run a conduit from the basement to attict in my house. If I move an outlet it looks like I can six inches of clearance on the first floor.

 

[upstatemike]

Whats the minimum distance I would want to run a conduit for low voltage from some high voltage wires?
I'm rather limited on the locations I can run a conduit from the basement to attict in my house. If I move an outlet it looks like I can six inches of clearance on the first floor.

As long as the conduit is metal and is grounded there should not be a distance requirement.

 

[Paul]

If you're using PVC conduit I believe cisco says a foot, but it's been a while.

 

[DrunkenLizard]

Thanks guys!

If you're using PVC conduit I believe cisco says a foot, but it's been a while.

I had already picked up some pvc conduit but the problem I'm running into is that none of my interior walls that are shared on the first and second floors are free of hv, looks like I might have to do some more extensive work then I thought and move some outlets and light switches. Hallways on both floors have lights that are controlled by three or more switches.

I guess it would probably be cheaper and easier to run metal conduit, to ground it would I just need to run a cable attached from the conduit outside to a buried rod? what guage wire would I want to use?

 

[nov0798]

It really doesnt matter, I have home network, and alarm system wiring running next to 240 volt hot tub lines, and have never had a problem.

 

[aehusted]

Whew!
I was about to get wound up about the previous answers.
I was worried about this as well until I read a bunch of posts here that convinced me not to worry about it. I too have network, alarm and audio wires running close to 120 with no problems.
I am sure if you are trying to max out your gigE speed this might be an issue, but I don't think it is really worth worrying about. The only time I have encountered a HV LV problem is at my parents house. Whoever ran the wires for the one sound system must have used some really cheap ass unshielded wire for the line out to the sub. When the sub is on and the receiver is off, there is an obnoxious (60Hz?) hum. It bugs the hell out of me, but they like it because it helps them remember to turn the sub off. When the receiver is on, there is no interference.

It really doesnt matter, I have home network, and alarm system wiring running next to 240 volt hot tub lines, and have never had a problem.

 

[nightwalker]

The general rule is to keep LV and HV 12 to 18 inches apart and to do your best to not run parallel for more than 8 to 10 feet if you're within that distance. It doesn't mean they can't get closer at times but you want to try to avoid it when you can.

 

[DrunkenLizard]

well I picked up some metal conduit last night, spent about $90 (ugh). really bums me out but It does look like the best I can do is running a 2in conduit 4-10 inches away from hv parellel for about 16 ft. I might be able to run a conduit in the garage up to the second floor now that I looked at things but its going to be a pita to get it over to the attict. for some reason there's a sub roof below the main roof of my garage, lower roof slops from about the top of the second floor down to just before the garage door and above that theres a peaked roof built ontop of it.

So right now i have 20 ft of 2in pvc conduit, 20ft of 2in emt conduit, and 20 ft of 1 1/2 in emt conduit.

Any advice on how to secure the metal conduit and how best to ground it?

I don't feel like returning the pvc cause that was less than $10 total, so I'll try to run that through the garage this weekend and run the grounded metal conduit up through the walls.

I need to get a lot of wire upstairs, 6 cat5e drops well lets make that 12 and hope that doesn't get used up to quick lol, 4-6 rg6 quad, and probably 20-25 mini coax drops, and leaving plenty of room for what I havent thought of.

Hmm probably should home run speaker cable for whole home audio and HT while I'm at it.
And I'm sure I'll be running wiring for alarm sensors and cameras this winter to.

edit:
I should mention that the wiring closet is in the basement on the wall that borders the garage, there's about a foot of that wall that extends up above where i think the garage floor is. Anyone know what code would typically be for running a conduit between the house and garage?

 

[DrunkenLizard]

To be honest with you, you probably just made the matter worse. Metal is a conductor and hence picks up stuff like radio waves, etc. You most likely would have been better off placing it in plastic conduit over metal. As I said earlier, I wouldnt worry about it. What exactly are you trying to protect from EMI?

eh, at least I kept my receipts. Just want to make sure I'm not going to have any problems with interference or signal degradation. I'll be running cat6 sometime soon, just have a couple cases of cat5e on hand so that will handle my needs for now. My office is on the second floor but I plan on moving my servers and such down to the wiring closet. Eventually I'll have a render farm down there so I'll need my gigabit ethernet to expand beyond my workstations upstairs.

 

[Brightan]

It all depends on what kind of cables you are running and what the signals are. Coax and especially quad shield coax are not going to be bothered by hv cables. Cat5/6 running Ethernet use differential drivers designed specifically to eliminate noise so I really wouldn't worry too much about them either. Low voltage signals like audio would be the most prone to noise but even then I wouldn't go to the extra hassle of a grounded metal conduit. If you are running audio, use a shielded cable and where you can, keep them a couple of inches from the HV. The reality is that there are usually compromises between the ideal and what your only choice might be. The bottom line is, IMHO, keep some distance where you can but don't be overly paranoid about it.

 

[upstatemike]

To be honest with you, you probably just made the matter worse. Metal is a conductor and hence picks up stuff like radio waves, etc. You most likely would have been better off placing it in plastic conduit over metal. As I said earlier, I wouldnt worry about it. What exactly are you trying to protect from EMI?

??? How is grounded metal going to make matters worse? All shielded electrical wiring is based on a grounded metal shield blocking noise from reaching the signal carrying conductors... that is how coax works. Grounded metal should block radio waves and EMF, not pick it up.

 

[nov0798]

Grounding it to what? Your home electrical ground? If your gonna ground something to isolate it from another possible source than it needs to be completely isolated. As for the topic of discussion, the original poster will not see or experience any difference by running the cables insode electrical conduit, or out in the open. Most likely they will also not see any noticible improvement between cat5e and cat6. What type of signals are running over the twisted pair anyway? The cat5e and cat 6, being twisted pair help to reduce/eliminate emi interference in their design alone.

 

[upstatemike]

Grounding it to what? Your home electrical ground?

Yes. Ground is ground is ground. There should not be more than 1 ground reference in your house or you will get ground loops. You do not want to have a different ground that is isolated from your electrical ground. (The ground wire in your romex is not the source of noise, it is the hot wires). If you have more than 1 ground rod for some reason then they all need to be bonded together or bad things will happen.

If you don't feel a grounded metal conduit is needed for a given application then that is a fair argument but I don't think it is right to suggest that it will cause a problem to use one... unless of course you create a new floating ground reference that is different from the main house ground.

 

[DrunkenLizard]

Just an update for anyone thats in the same boat, I ended up running a 2in pvc conduit from the basement into the garage then up the wall to the crawlspace above the second floor. This was a lot easier than tearing into the wall in the middle of the house to try and run a conduit around all the hv. I've run 10 precision mini coax, 3 rg6 q, and 7 cat 5e through it so far. Starting to get a little tight I might run a second conduit so I can get 15 more mini coax, some speaker wire, more coax and maybe some vga run up to the attic for the second floor. I should have run more mini coax to begin with but I was lazy and somehow didn't think I would want tv in my office <_< I also want to add a return component feed from the loft so I can play a game in my office if the console is in the loft. and is it overkill to drop video feeds to the bathroom?