multiple cables in conduit?

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  #1  
Old 10-09-12, 08:19 AM
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multiple cables in conduit?

can 2 or 3 UF cables be run in the same PVC conduit? trying to think of designs for my outside lighting and nothing is near final but this will influence my next step
 
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Old 10-09-12, 08:47 AM
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Running pvc pipe for outside lighting and wiring is the only true way to do it right. In using a conduit like that you would not use UF wire. You would be using individual wires like a white, a black and a green. Two circuits...you would use a second black or another color and so on. This wire is called type THHN or THWN; It comes on spools. The amount of wires in the pipe is limited by the code. Pulling UF in a conduit is a very difficult job also. Using 1/2" pvc would give you roughly 3 circuits and 3/4" would yield 5 or so. Also with pvc, depending on spare room, you could pull more wires in the future.
 
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Old 10-09-12, 08:51 AM
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Basic answer is cables should not be run in conduit though it is not an NEC violation. Conduit should only be used as sleeves to protect the cable where exposed to possible damage such as where it leaves or enters a protected space and goes into the ground.

If you are going to run continuous conduit best practice is to use individual conductors, usually THWN.
 
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Old 10-09-12, 09:43 AM
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This wire is called type THHN or THWN; It comes on spools.
THHN is not rated for use in underground conduit. THWN is. The "W" indicates Water resistant. That said, most of the individual conductors available these days are rated, and marked, THHN/THWN. Just make sure the W is in the designation on the wire you buy.

You can pull up to 10 #14 wires or 7 #12 wires in 1/2" PVC. In 3/4", it's up to 18 # 14 wires or 13 #12 wires. I would advise installing 3/4" Schedule 40 PVC, for ease of pulling, even if you don't foresee needing that many wires.
 
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Old 10-09-12, 10:19 AM
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well if i can run uf without conduit maybe i'd do that even! would be easy as pie then

let me tell you what i'm doing, maybe that will help with things

my breezeway will be 'switch central' ...it's enclosed and safe from direct water but of course open to the 'weather'

im going to tap off an outside outlet in the breezeway and make it into a few switches plus of course the existing outlet in the box. this will be barely 100 to 200 watts of CFL so i know it wont be an issue load wise

i want one switch to operate 2 or 3 soffit lights in front of the house

1 switch will be for the 'spa area' (i want the ability to turn off the spot while i'm out there)

undecided yet is whether that spa light switch will operate the 2 or 3 other lights for the rear yard but for the sake of planning lets say they will be on a separate switch so the rest of the house is lit up while the spa is dark. so in that case i would like to run the wires for both switches thru the same PVC to keep things cleaner looking vs having 2 pvc pipes running side by side.

thus the question about running the wires in the same conduit. then again if i can run UF and just staple it to the wooden soffit. i may consider that..i also need to run the cost of single strand vs uf as well. there woudl also be about 50 ft of house with no soffit and i guess id just get concrete fasteners to go thru the permastone and attach the UF directly

i'm not really hung up on aesthetics toooo much...as long as the wires are run straight i think i'd be happy plus the grey would blend with my grey permastone better than painted pvc of any diameter

if you can think of any better way to switch things i'm open to it but i think it's relatively simple with not a lot of room for different things done.
 
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Old 10-09-12, 10:56 AM
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Even if you use Type UF, it will need to be sleeved in conduit where exposed to damage. That is, all through the switches, until you get up to the underside of the soffit. If the conduit ends there, it will need to be sealed against moisture.

If you've never worked with Type UF, I can tell you from experience that it is a PITA. It is very difficult to strip the rubbery sheath without nicking the insulation on the conductors inside or cutting yourself, or both. As another member said here awhile back, "I can have everything connected (with individual conductors) while you are still stripping the first end of the UF."
 
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Old 10-09-12, 11:18 AM
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i'm pretty sure i used the UF on another project...installed 2 lights outside the garage thru the wall. but that was over a year ago...i bought the special stripper and it takes 3 seconds to strip..

but maybe it was another type of wire since you are saying it's not supposed to be that ez especially for a novice like me or maybe the job just wasnt that complicated.

i also think i'm not understanding the point of UF if it needs sealed for moisture...not that it's hard to silicone up the end of a pipe but if this cable is rated to be buried in dirt, why would a little rain hurt it above ground especially under a soffit? i think maybe logistically we are thinking 2 different things maybe?

i do understand the need for the conduit at the 'eye level' area like when it comes down from the ceiling and ends in the swtichbox. but other than the rise from the switches to the ceiling in breezeway, the wire will never be 'within reach' so in theory i dont have to sleeve it at all do i?
 
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Old 10-09-12, 11:40 AM
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i bought the special stripper and it takes 3 seconds to strip..
I'd love to have one of those. Could you post the make and model? Seriously, I don't think they exist.

i also think i'm not understanding the point of UF if it needs sealed for moisture...not that it's hard to silicone up the end of a pipe but if this cable is rated to be buried in dirt, why would a little rain hurt it above ground especially under a soffit? i think maybe logistically we are thinking 2 different things maybe?
You're right. Nobody cares if the cable gets wet; it's made to. But the code requires that all raceways be sealed if they provide a path for water to come into contact with live parts - such as switches. You could just seal the conduit at the switch box and meet this requirement, but that would gaurantee that any water that got into the pipe would just stand on that seal until it evaporated - or the seal failed.

other than the rise from the switches to the ceiling in breezeway, the wire will never be 'within reach' so in theory i dont have to sleeve it at all do i?
Nope. From the receptacle through the switches and then up to the soffit would be the minimum.

Type UF is not inexpensive, but it might be less than the pipe and the individual conductors. You'll just have to see.
 
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Old 10-09-12, 12:06 PM
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hmmm sounds like basically i should just do conduit until i get outside the breezeway, seal that end..then run the UF to whereever i need to


pretty sure it's these...was so simple wasnt funny. but this cant be what you mean because you would have found it long before i did!


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Old 10-09-12, 01:07 PM
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Those are wire strippers. UF has the inner insulated wires fused into the outer sheath and separating the wires from the sheath is the difficulty. If you didn't have difficulty you may have had NM cable not UF cable.
 
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Old 10-09-12, 01:10 PM
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hmm now you make me wonder...i have a spare piece of wire at home on the shelf.i'm assuming the designation is on the wire..i gotta look when i get home to solve the mystery.

if i got NM i hope it's ok for my other lites cause i'm not changing it lol.
 
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Old 10-09-12, 03:03 PM
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it says 12 awg UF-B..is that what you mean?

so i guess i'm like columbus making a new discovery?
 
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Old 10-09-12, 06:06 PM
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THHN is not rated for use in underground conduit. THWN is. The "W" indicates Water resistant. That said, most of the individual conductors available these days are rated, and marked, THHN/THWN. Just make sure the W is in the designation on the wire you buy.
Just an FYI - I have never seen THHN wire that was not duel rated as THWN (among other ratings) But yes, you should make sure.
 
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