I know that you are not allowed to mix, say a low voltage line in a
conduit with line voltage wires. My question is, can you mix them if
either the line voltage wires or the low voltage wires are in their own
"conduit" inside of the larger conduit? I have a 2" diameter plastic,
flexi conduit going from my house to an area out by the road. Right now
it is used to bring 120 volts to a post lamp and an outlet in its base.
Now, if I wanted to run some low voltage lines, could I put them in a
piece of Greenfield (grounded of course) and run that Greenfield with
its low voltage wires, through the same conduit?
Would think so -- seems like it would be similar to Wiremold 5000 where line
voltage and low voltage wires are in the same enclosure but separated by a
physical barrier so they can't touch each other.
I've run low voltage control cable in the same conduit as the power
supply but it had insulation that matched the voltage rating of the
power cable. It really depends on the folks who have jurisdiction
over the inspection of the job. I've done work where The Army Corps
of Engineers was the inspection authority and sometimes they are much
stricter than what the NEC calls for. o_O
I'd certainly think so. Innerduct is common enough inside a larger
conduit, and I don't know of anything in the NEC that cares about
anything beyond the conduit enclosing a particular wiring. If wiring x
is good inside conduit x it shouldn't matter if the whole thing is in
larger conduit y as long as the conduit y fill specs are ok.
My normal recommendation is that when someone is running conduit they
run extra for potential future uses since conduit is cheap, particularly
PVC conduit. In a case like yours I would have suggested parallel runs
of 3/4" PVC conduit for just such future cameras, intercoms, gate
operator controls or whatever.
I "think" it boils down to if it is considered a "conduit" or a
"raceway" Can't use NMD (or metallic sheathed either) cable in a
conduit, but I believe it is acceptable in a raceway. Cables of
different voltages are allowed in a raceway. Wires of different
voltages must be segregated in a raceway.
Wires of different voltages are not allowed in a conduit. Can a
"conduit" be used as a "raceway"???
On Fri, 12 Apr 2013 19:44:58 -0400, firstname.lastname@example.org wrote:
A conduit is a raceway, You are thinking about a duct.
Conduit is just one type of raceway.
The difference is a raceway terminates at both ends in a box or
enclosure. A duct is usually open at both ends.
There are actually ways to run a line voltage and a low voltage
"cable" in the same conduit/raceway but they must be split out and
terminate in different enclosures.
On 4/12/2013 10:10 PM, email@example.com wrote:
Power wires of different voltages can be run in a conduit, which is a
If the OP is running "class 2" wiring (as used for doorbells,
thermostats,...) the wires can be run together if
"Either (a) all the ...power... conductors or (b) all of the Class 2 ...
circuit conductors are in a racway, ... or Type UF cables." (725.136-I-1).
The OP is not specific what "low voltage lines" are, or how many. If
class 2, running either the power or the class 2 as UF cable would work.
If you run one of them in a raceway I would suggest plastic ENT instead
If it is going to be inspected, I would run the plan past the inspector.
I agree about asking the inspector. The code says cable jackets are
separation but the rub usually comes in when you terminate the cables.
If you can split them out of the raceway system into separate
enclosures before you crack into the jacket, it is legal but a lot of
inspectors will still fail it. I have seen this done with "T" body
condulets on both ends.
Usually it is simply easier to run separate conduits.
On Apr 13, 11:09 am, firstname.lastname@example.org wrote:
Seems like the easiest solution is to run a 14 gauge cable in the same
tube/pipe/raceway/conduit as the power cable, then you can do anything
you want with the extra cable, whatever the local codes require/
Thanks to all who replied. Some of my questions were curiosity based on
stuff that I am or will be working on. I do have a 2" plastic conduit
which presently has 120 volt UF cable in it for the said post lamp.
Other low voltage things might be a speaker line or 12 volts for
In addition, my subdivision has a gate at the entrance. The gate
controller has the ability to allow a visitor to look up each resident
and call the resident. The resident can, via phone keypad, open the
gate. Right now there is no phone line connected to the gate
controller. However, there is a phone line about 30' from the gate
controller, which is owned by me, but it must cross the asphalt. There
is a 3" (I think) conduit under the asphalt. The possibility is run the
phone line through that conduit to the gate controller. There are 120
or 240 volt lines in the conduit. So, the phone line should probably be
run using an ENT or equivalent, inside the original 3" conduit.
On Sun, 14 Apr 2013 09:46:03 -0500, The Daring Dufas
Legally, cables are cables. For the purposes of this, UF is the same
The main issue is how you get these cables into and out of the conduit
without getting into the jacket. Neither can terminate in an enclosure
with the other. That is why inspectors usually just say no.
The option most likely to survive is simply a sleeve that is not
ending on an enclosure at each end. Then the cables just use that as a
Discrete conductors would need to be in a flexible raceway of some
type. (Greenfield, Sealtite or Smurf)
If you have a box or conduit body at both ends where the cables split
out as undisturbed cable and terminate in separate boxes, you are OK
Another option would be one big box, partitioned into 3 separate
areas, one for the entrance of the cables, where they split out and a
separate area on each side where low and line voltage get terminated.
All that said, there are still plenty of inspectors who will not
accept 725 (low voltage) wiring in the same pipe as chapter 3 (line
voltage) wiring, no matter how you do it.
On 4/14/2013 10:22 AM, email@example.com wrote:
I suppose it would all depend on the engineering department in your
jurisdiction? I've done work for The Army Corps of Engineers and if we
approached them with a problem that seemed like it was outside normal
practice, they would allow our solution if they deemed it safe. o_O
I pretty much think I could get away with anything here, but, using the
flex plastic stuff, inside the larger conduit, should work. Where the
large conduit terminates at a box, the flex plastic could just go into
the box and out through a hole, thus keeping it fully segregated.
I did mention the low voltage cable having a voltage rating on par with
the higher voltage cable. Most low voltage cable I work with has 300
volt insulation when most house wiring in The U.S. has insulation rated
for 600 volts. There is also the problem of inductive pickup from power
cable to low voltage cable. Many years ago, I worked in the burglar
alarm industry and I tried my best to get the owner not to run the alarm
lines along with the Romex power cable in homes. Whenever lightning
struck close by, there was an inductive coupling to the low voltage
alarm wires and the alarm panel often got zapped. Even though there were
MOV's on the circuit board, the darn things would explode with the first
strike and the IC chips would blow off the circuit board by the second
strike. I often run shielded low voltage cable if it's going to be run
in close proximity to power cable but if installing something new, MC
cable run for the power is less expensive than finding shielded low
voltage cable for a particular section. If I'm running PVC electrical
conduit underground to an out building and there needs to be an
extension of the alarm system, a remote control or POTS line, I'll pull
MC cable for the power and not worry about the low voltage cable in the
same conduit. On the other hand, if I'm going to pull a 4 wire 100amp
circuit in a large underground conduit and wish to share the space with
a low voltage circuit or two, I'll pull in some flexible metal conduit
to put the low voltage cable in. I always have a pull string in there
I think this is a good idea, but it brings back memories of a fire in a
telephone central office. They had always mixed cables in the rack.
There were large (like your thumb) cables for DC power, MC cables for AC
power and also a lot of multipair telephone type cables. Apparently,
while removing cables from the rack, the MC cable wore the insulation
from one of the DC power cables and caused the fire. Even though the
damage was confined relatively small area, it knocked out communications
in a very large area for a relatively long time. After that, they were
going to segregate the cable types.
Somebody wasn't paying attention when the wire was being removed. There
have been many explosive events when someone decided to yank out wire
from an energized system. I've also worked high voltage underground
power in the 4,160 volt range and even though that's one of the lower
distribution voltages it's still extremely dangerous to the un-careful.
On 4/15/2013 10:33 AM, firstname.lastname@example.org wrote:
I realize that and most folks have no clue as to the DC power and size
of the battery banks and power supplies it takes to run a central
office. I don't have as much experience with switches as I'd like but
the last one I fooled around with was a Dimension 2000 which replaced
what was said to be a more reliable crossbar switch on an island where
the missile test range was where I worked for a while. o_O
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