Is it kosher to have a low-voltage line for outdoor lights in the same conduit as a UF cable for an outdoor plug?
clients want to bring low voltage line from the transformer in the basement to a zone that is isolated by hardscape. The only easy way to get there would be to come through a run of 1″ conduit that feeds an outdoor plug.
thanks
k
Replies
Unfortunately, no. Low voltage must be separated... cannot be in the same conduit.
rats. why is that?
k
Since it looks like the same post is in two different places, here's my rationale as to why I don't believe it's allowed. I'll let others chime in on whether I'm right or wrong...
http://forums.taunton.com/tp-breaktime/messages?msg=113620.4
you're right- it is me posting in two places. i started in general discussion, then realized i should maybe have put it in energy, etc. folder. more responses are happpening in general discussion, though.
k
I'm not sure LV lighting qualifies as "power limited", since there's a lot of current in them thar wires.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
Please look here
113620.2
That would suggest that if you used UF for the LV lights you're OK. But good luck getting 2 UFs through a 1" conduit.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
No it doesn't. You don't have to match cable type. A conductor is a conductor, the requirement applies to the rating of the insulation around the conductor.
Edited 12/6/2008 7:52 am ET by England1
Edited 12/6/2008 7:52 am ET by England1
The problem is finding appropriate cable with the (certified) voltage rating. Your standard LV zip cord likely isn't rated more than 50V.
One thing that isn't clear is why the 120V cable needs to be UF (if it does). If it doesn't need to be UF then that opens up several options.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
In this case UF b/c of conduit and plug in wet location. Is that not necessary? I could change it.
k
You don't generally need UF in conduit. Presumably it's needed for the portion of the cable that isn't in conduit.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
Depends on how you answer the other question I asked in my later post. If you have a continuous conduit run from underground to your outlet box, I don't see the need for the UF. Just individual THWN-insulated (not THHN) conductors.
good points/ questions. the plug is of course gfci protected. I was assuming I'd pull two new lines rather than try to fish the LV through on top of the UF. I can't vouch for the quality/watertightness of the conduit run, I'm viewing it simply as the only chase from point A to point B.
k
<That would suggest that if you used UF for the LV lights you're OK. But good luck getting 2 UFs through a 1" conduit.>
Which is another option, of course- put the transformer out in that inaccesible zone. But the clients already have one in their basement, so we're trying to get around that.
As far as whether I can get a regular LV line with HV insulation, I'll have to look into that.
thanks for the interest.
kadditional edit: I realize now that you weren't talking about stepping down to LV in the zone in question, that you were talking about pulling UF for LV... sorry for the confusion. You don't think I could pull two NM UF lines through 1"? With a lot of lube?
Edited 12/6/2008 10:56 am ET by KFC
Edited 12/6/2008 11:13 am ET by KFC
This is another source of inspector fights. The NEC also says a cable jacket is "separation".
There is a difference between "conductors" and "cables".
The real issue then becomes how you terminate the UF at each end. You can't strip the UF in the same box as the LV cable.
correct me if I'm wrong, but i think the UF doesn't need to be in conduit anyway, so perhaps i could just get both lines to the inaccesible zone through the conduit, then cut the conduit there and let them go their separate ways, until the UF goes back into the conduit for the plug?
k
If you are just using the conduit as a sleeve through the inaccessible part and these "go their separate ways" as cables on each end, I do not see the problem. Just look for the voltage rating on the low voltage wire to be safe. I bet it is 300v if it is the stuff that comes from Malibu. It should be molded in the insulation every couple feet.
I even tend to disagree with the "interference" issues if data cable is coax or twisted pair but that is another mud hole we don't need to roll around in today.
The real issue then becomes how you terminate the UF at each end. You can't strip the UF in the same box as the LV cable.
Nope ... not true
wait, which part is not true- that you can't strip them in the same box, or that whether you can or can't is the real issue?
k
There is so much ground covered by the term "low voltage!" Let's look at a few examples, and try to imagine the effects of mixing voltages in the same pipe / enclosure.
There's the original max of, say, doorbell wire and household power. Generally, there's not going to be a problem; the bell wire is likely rated for at least 150 volts, and it takes real current flowing to sound the doorbell.
Then there is the mix of telephone wire and power wire. While the phone wire is likely also insulated to 150 volts - the bell ringer voltage is typically about 90 volts - if you have the two wires next to each other for any distance, the power wire will induce a 'hum' on the phone line. Not a good result.
If the low voltage wire is carrying data, or used in controls, the induced voltages from the power line will corrupt the data, and may fool control electronics into thinking that something should operate (or block the transmission of a control signal). All bad results.
An example of this might be when the HVAC guy runs the thermostat wire together with the power wire from the disconnect to the condensing unit. If the HVAC controls are electronic, if the thermostat is electronic, the unit may not operate properly because of the induced interference.
A gfretwell has pointed out, there's the issue of where the cables terminate. It's not likely that they're going to the same place.
This brings us full circle to one of the first lines in the code book : The NEC is not a design manual! I am sure we can all think of ridiculous things we can do, that are not against any law. Such is the case here.
Don't run LV and power together. Trust me on this - it will only bring you trouble.
In this case, the LV is for outdoor lighting, and the UF is for an outdoor plug, so I assume interference of the telephone/computer line type isn't in play. They would not be terminating in the same place.
If it didn't mean breaking out mortared brick and cutting/coring/tunneling under a patio, I wouldn't be pressing the issue. Yet another example of the benefits of burying chases when isolating zones with walkways or other hardscape...
Still, I do hear your reasoning... even if I kinda don't want to. :(
k
Honestly, I'd make an anonymous call to the local AHJ (aka electrical inspector) in your area. My area, they wouldn't allow it (if they knew about it ;-) ), but I did some checking and other areas, it's allowed (as seen in this discussion: http://forums.mikeholt.com/showthread.php?t=90288&highlight=landscape+light).
Your current installation... as others have asked, why the UF cable? Does the conduit run continuously from underground to the box? Or does the cable exit the conduit and run exposed in some manner to the outside outlet? Is the cable GFCI-protected (i.e. via a GFCI breaker or upstream GFCI outlet), or is the outlet GFCI-protected? How deep is the conduit buried? (I ask since putting UF in conduit seems like a HO install, which makes me wonder if the conduit is properly buried).
I ask these questions since the pragmatic side of me thinks I'd be trying to bend the rules on this one (which might be unpopular here). When you're facing a huge tear-up for something like this, I'd try to do the installation as safe as possible without the huge mess. The wires together in the conduit really "shouldn't" be a problem... the real sources of problems are typically termination points where incidental contact could occur.
The moral of the story... if you're digging a trench for conduit, it's good to add that spare conduit or two for just these cases. Too bad not enough people think ahead...
To answer DanH's question, I use that term ("power-limited"), since that's what Class 1/2/3 applies to... "Remote-Control, Signaling, and Power-Limited Circuits". Really, low-voltage lighting is pretty low power. A typical el-cheapo low-voltage lighting transformer may only put out around 88W. Not a whole lot of power...
My recollection of "power limited" is that it's limited to a watt or two. But I don't have my code book at hand to check.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
Class 1 power limited is 1000va 30v or less.
Accepted wiring methods look a lot like regular line voltage.
There is a lot of gray area in what people call "low voltage" and the NEC generally gets ignored. States are trying to rein this in with low voltage licensing and inspection but old habits die hard. NFPA would help his along if they made article 725 easier to understand.
Edited 12/7/2008 11:49 am ET by gfretwell
Just looked it up (via Mike Holt, not the not-so-easy to interpret NEC). To summarize the information:
Class 1: 2 variations: 1. Power-limited: up to 30V, limited to 1000VA. 2. Nonpower-limited, up to 600V.
Class 2: 30V or less, power-limited to 100VA OR over 30V, limited to 5 mA. According to the information, the idea is that the voltage is limited to make it more shock-resistant, and the energy is limited to render the circuit safe from fire.
Class 3: Over 30V, used when the power demand is between 0.50VA and 100VA. Due to higher voltage, not necessarily safe from a shock-perspective. Lower energy makes the circuits safe from fire.
Edited 12/7/2008 12:47 pm ET by RustyNail
I just looked at Malibu transformers and they are all 12v from 44w (class 2) to 600w (class 1) without any real change in the wiring method they sell you with them or a significant difference in the installation instructions.
As I said, in low voltage, the NEC is largely ignored. IMHO
The wire I have, that I believe was supplied in a Malibu set, is marked 300v. I am guessing that is just because that is the way most zip cord was manufactured and it was as easy to use this as make up something special. I suppose YMMV with the current offshore supplied product.
So, um, is it kosher to have a low-voltage line for outdoor lights in the same conduit as a UF cable for an outdoor plug?
<JK>. sort of.
k