Mixing thermostat and power wiring in same conduit whip (from disconnect to Heat Pump unit)

[Howard]

I'm replacing an old heat pump installation which had the thermostat
wiring and the 220V romex all within the same plastic conduit whip
going from disconnect to the condenser unit.

I understand thisn't acceptable per current code. I need a couple
clarifications.

1. Can std. Romex wire be used in a conduit or does it need to be
individual wires? (ie THHN)
2. It appears that thermostat wiring is permitted within a conduit if
it's insulation is rated for the same voltage as the high voltage
circuit. (ie CL1 220V). However can std. thermostat wire (ie 18/4)
be contained in it's own small conduit within the main conduit??

[Noon-Air]

Post by Howard
I'm replacing an old heat pump installation which had the thermostat
wiring and the 220V romex all within the same plastic conduit whip
going from disconnect to the condenser unit.

If you were a *competent*, licensed, insured, professionaly trained, HVAC
technician, you would already know the answers to your questions.
The answers you seek are in the NEC, and I believe also in the UMC
Maybe you should check with you local building inspectors?? You *did* pull a
permit, didn't you??
I will however give you some answers below...keep in mind that these answers
are based on the requirements in my location.

Post by Howard
I understand thisn't acceptable per current code. I need a couple
clarifications.
1. Can std. Romex wire be used in a conduit or does it need to be
individual wires? (ie THHN)

Romex won't pass inspection here.... use properly sized THHN

Post by Howard
2. It appears that thermostat wiring is permitted within a conduit if
it's insulation is rated for the same voltage as the high voltage
circuit. (ie CL1 220V).

Not allowed here at all

Post by Howard
However can std. thermostat wire (ie 18/4)
be contained in it's own small conduit within the main conduit??

If its a heat pump, you will probably have more than 4 wires. Control wires
should be in their own seperate conduit, period.

[Jeffrey Lebowski]

Post by Noon-Air

Post by Howard
I'm replacing an old heat pump installation which had the thermostat
wiring and the 220V romex all within the same plastic conduit whip
going from disconnect to the condenser unit.

If you were a *competent*, licensed, insured, professionaly trained, HVAC
technician, you would already know the answers to your questions.
The answers you seek are in the NEC, and I believe also in the UMC
Maybe you should check with you local building inspectors?? You *did* pull a
permit, didn't you??
I will however give you some answers below...keep in mind that these answers
are based on the requirements in my location.

Post by Howard
I understand thisn't acceptable per current code. I need a couple
clarifications.
1. Can std. Romex wire be used in a conduit or does it need to be
individual wires? (ie THHN)

Romex won't pass inspection here.... use properly sized THHN

Post by Howard
2. It appears that thermostat wiring is permitted within a conduit if
it's insulation is rated for the same voltage as the high voltage
circuit. (ie CL1 220V).

Not allowed here at all

Post by Howard
However can std. thermostat wire (ie 18/4)
be contained in it's own small conduit within the main conduit??

If its a heat pump, you will probably have more than 4 wires. Control wires
should be in their own seperate conduit, period.

If class 2 or class 3 power source is used then no raceway is required.

See nec article 725

Anyways, standard practice at least in my area is to route thermostat wire
along with the copper lineset between the condensor and ahu--the outer pvc
jacket holds up just fine under outdoors weather condition.

--

[RBM]

You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it is
not rated for wet locations. Most, but not all conductors have multiple
ratings, so for wet locations be sure it has a letter "W" in it like THWN

Post by Howard
I'm replacing an old heat pump installation which had the thermostat
wiring and the 220V romex all within the same plastic conduit whip
going from disconnect to the condenser unit.
I understand thisn't acceptable per current code. I need a couple
clarifications.
1. Can std. Romex wire be used in a conduit or does it need to be
individual wires? (ie THHN)
2. It appears that thermostat wiring is permitted within a conduit if
it's insulation is rated for the same voltage as the high voltage
circuit. (ie CL1 220V). However can std. thermostat wire (ie 18/4)
be contained in it's own small conduit within the main conduit??

[Noon-Air]

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it
is not rated for wet locations. Most, but not all conductors have multiple
ratings, so for wet locations be sure it has a letter "W" in it like THWN

Thats why its run in Carflex or Sealtite
but then you probably knew that, right??

[RBM]

Sealtite can be run in "wet" locations like underground, and when it is,
THHN is not an acceptable conductor

Post by Noon-Air

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it
is not rated for wet locations. Most, but not all conductors have
multiple ratings, so for wet locations be sure it has a letter "W" in it
like THWN

Thats why its run in Carflex or Sealtite
but then you probably knew that, right??

[Art Todesco]

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it is
not rated for wet locations. Most, but not all conductors have multiple
ratings, so for wet locations be sure it has a letter "W" in it like THWN

While you could do it, I thought that
once a low voltage wire was contained
in a conduit or raceway, it has to be
treated as a line voltage conductor, even
after it emerges from the conduit.

[RBM]

In the heat pump there will be separate compartments for line and low
voltage. He would have to maintain line voltage conductors until he's into
the low voltage compartment. IMO it's not a practical way to wire the thing

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it
is not rated for wet locations. Most, but not all conductors have
multiple ratings, so for wet locations be sure it has a letter "W" in it
like THWN

While you could do it, I thought that once a low voltage wire was
contained
in a conduit or raceway, it has to be treated as a line voltage conductor,
even
after it emerges from the conduit.

[Jeffrey Lebowski]

Post by RBM
In the heat pump there will be separate compartments for line and low
voltage.

And you completely sure about this ?

--

[dreamchaser]

Noon-Air, get a life. So I guess you are a competent, yatta yatta,
licensed blah blah. Go sniff some more freon!!

Howard, check with your inspector. If you can route the tstat wiring
along the outside of the conduit that has the power wiring, just do
that and buy some wire ties. Of course, if you need it protected
because of animals, heathens, teenagers running weedeaters, then just
run the flippin thing in another piece of flex.

Congratulations for doing your own work. It saves a hell of a lot of
money and you won't rip yourself off like a lot of competent, insured
blah blah contractors will, and you will do a better job then a lot
of them. Go for it!!

[Noon-Air]

Post by dreamchaser
Noon-Air, get a life. So I guess you are a competent, yatta yatta,
licensed blah blah. Go sniff some more freon!!

Actually I have been a contractor for over 10 years and add to that 22 years
of training and experience in the military.
Sniffing "freon"??? LOL....FREON is a registered trademark of Dupont Corp.
Sniffing a trademark?? What an idiot.

Post by dreamchaser
Howard, check with your inspector. If you can route the tstat wiring
along the outside of the conduit that has the power wiring, just do
that and buy some wire ties. Of course, if you need it protected
because of animals, heathens, teenagers running weedeaters, then just
run the flippin thing in another piece of flex.

Dumbshit... thats what I told him...

Post by dreamchaser
Congratulations for doing your own work. It saves a hell of a lot of
money and you won't rip yourself off like a lot of competent, insured
blah blah contractors will, and you will do a better job then a lot
of them. Go for it!!

Yeah right... there are some parts of the country(US) where its ILLEGAL for
unlicensed homeowners to do their own HVAC work. Even here in backwoods
south Mississippi, if you DIY on an HVAC system inside of the city limits,
after you have to rip it back out, and pay the fines, then pull a permit,
get it reinstalled by a licensed contractor, and get it inspected, you would
have been a whole lot better off getting it done right in the first place.
But your too ignorant to figure that out for yourself.

Now Greg, Since your so eager to spout off, what is your profession?? are
you in business?? How long have you been a certified Master of your
profession?? What are the inherent hazards to your customers, their
families, and their homes if you screw up?? How much training, education and
experience do you have in your profession?? How much continuing education
are you required to have to maintain your certifications?? Or do you really
want to go there?? Maybe you should quietly go away.

[BARK]

ssis

oH HES FRROM MISISIPEE, IT adds up now

[ftwhd]

Post by dreamchaser
Noon-Air, get a life. So I guess you are a competent, yatta yatta,
licensed blah blah. Go sniff some more freon!!

He is a successful one man and a half man band after ten years of
being in business. I think hes sniffed enough Freon. :) Steve.

[Jeffrey Lebowski]

Post by dreamchaser
Noon-Air, get a life. So I guess you are a competent, yatta yatta,
licensed blah blah. Go sniff some more freon!!

I'm not Noon-Air, you stupit fuck.

Suggest learn to post, moron....

Post by dreamchaser
Howard, check with your inspector. If you can route the tstat wiring
along the outside of the conduit that has the power wiring, just do
that and buy some wire ties. Of course, if you need it protected
because of animals, heathens, teenagers running weedeaters, then just
run the flippin thing in another piece of flex.
Congratulations for doing your own work. It saves a hell of a lot of
money and you won't rip yourself off like a lot of competent, insured
blah blah contractors will, and you will do a better job then a lot
of them. Go for it!!

--

[Bud--]

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it is
not rated for wet locations. Most, but not all conductors have multiple
ratings, so for wet locations be sure it has a letter "W" in it like THWN

I believe mixing the power and control wires in the same conduit changes
the Class 2 control circuit into a Class 1 circuit. A Class 1 circuit
generally has to be wired as normal line voltage circuits - Romex, EMT,
boxes; #18 may be used if appropriate. That would apply to all the
control circuit connected to those wires, like the wiring to the
thermostat. Control wires in the disconnect makes the control circuit
Class 1 also.

Line and low voltage wiring can go to the same enclosure when connecting
to the same device in that enclosure, like a relay.

You could probably mix UF (instead of Romex) for power plus a control
cable in the same conduit (but I didn't look it up).

--
bud--

[RBM]

I agree except I believe that once the class 1 conductors leave a class 1
location, they can be transitioned back to class2. For example, and air
handler built by "First", instead of running class 2 low voltage into the
unit and make connections on an isolated board, they run what appears to be
MTW out of the machine and leave tails for connection to class 2 low
voltage. Similarly, in any AC condenser, your class 2 conductors are
connected to line voltage conductors before entering the line voltage
compartment for connection to the contactor

Post by Bud--

Post by RBM
You could run the low voltage with the line voltage if you use "line
voltage" conductors, which will probably be rated 600 volts, and although
'THHN is often bantered about as the conductor of choice, keep in mind it
is not rated for wet locations. Most, but not all conductors have
multiple ratings, so for wet locations be sure it has a letter "W" in it
like THWN

I believe mixing the power and control wires in the same conduit changes
the Class 2 control circuit into a Class 1 circuit. A Class 1 circuit
generally has to be wired as normal line voltage circuits - Romex, EMT,
boxes; #18 may be used if appropriate. That would apply to all the control
circuit connected to those wires, like the wiring to the thermostat.
Control wires in the disconnect makes the control circuit Class 1 also.
Line and low voltage wiring can go to the same enclosure when connecting
to the same device in that enclosure, like a relay.
You could probably mix UF (instead of Romex) for power plus a control
cable in the same conduit (but I didn't look it up).
--
bud--

[Jake]

Look Guys....

As to your debating Class 1 or 2 or THHN or THWN or UF or whatever....

Running a control circuit in the same raceway as a branch circuit is a
bad idea for reasons that have nothing to do with the code...

Low voltage, current limited control circuits can.. and have...
generated all kinds of havoc when run in close proximity to branch
conductors that might induce voltage into the control line.

Contactors can 'mysteriously' pick-up at odd times, OD temp. sensing is
screwed up, solid state controls will go absolutely wack-o.

Jake

[Bubba]

Post by Jake
Look Guys....
As to your debating Class 1 or 2 or THHN or THWN or UF or whatever....
Running a control circuit in the same raceway as a branch circuit is a
bad idea for reasons that have nothing to do with the code...
Low voltage, current limited control circuits can.. and have...
generated all kinds of havoc when run in close proximity to branch
conductors that might induce voltage into the control line.
Contactors can 'mysteriously' pick-up at odd times, OD temp. sensing is
screwed up, solid state controls will go absolutely wack-o.
Jake

Thank You Jake. Absolutely correct. Line voltage and low voltage in
the same conduit or sealtite is a problem waiting to happen.
Im glad you explained it in very simple terms.
Bubba

[Art Todesco]

Post by Bubba

Post by Jake
Look Guys....
As to your debating Class 1 or 2 or THHN or THWN or UF or whatever....
Running a control circuit in the same raceway as a branch circuit is a
bad idea for reasons that have nothing to do with the code...
Low voltage, current limited control circuits can.. and have...
generated all kinds of havoc when run in close proximity to branch
conductors that might induce voltage into the control line.
Contactors can 'mysteriously' pick-up at odd times, OD temp. sensing is
screwed up, solid state controls will go absolutely wack-o.
Jake

Thank You Jake. Absolutely correct. Line voltage and low voltage in
the same conduit or sealtite is a problem waiting to happen.
Im glad you explained it in very simple terms.
Bubba

Yes, this is similar to the problem at
the Hinsdale, IL telephone office a
few years ago. Office personnel was
pulling cables in the cable racks,
when a flash (spark) occurred. They had
Greenfield carrying AC and
other large 48 volt DC in the same
rack. Immediate investigation showed
nothing. Of course, there are millions
of wires in a telephone office, so it's
like looking for a needle in a haystack.
A few days later, a fire broke out
on Mothers' Day evening when no one was
in the building. And, these
wires were not even in the same conduit,
just the same raceway.

[g***@gonefishin.net]

Post by Bubba

Post by Jake
Look Guys....
As to your debating Class 1 or 2 or THHN or THWN or UF or whatever....
Running a control circuit in the same raceway as a branch circuit is a
bad idea for reasons that have nothing to do with the code...
Low voltage, current limited control circuits can.. and have...
generated all kinds of havoc when run in close proximity to branch
conductors that might induce voltage into the control line.
Contactors can 'mysteriously' pick-up at odd times, OD temp. sensing is
screwed up, solid state controls will go absolutely wack-o.
Jake

Thank You Jake. Absolutely correct. Line voltage and low voltage in
the same conduit or sealtite is a problem waiting to happen.
Im glad you explained it in very simple terms.
Bubba

sure would be nice if the ductless-mini-split manufacturers climbed on
board. seems like they're all running Hi & low volts in the same
umbilical cord....of course, WTF do they know....

[ftwhd]

Post by g***@gonefishin.net

Post by Bubba

Post by Jake
Look Guys....
As to your debating Class 1 or 2 or THHN or THWN or UF or whatever....
Running a control circuit in the same raceway as a branch circuit is a
bad idea for reasons that have nothing to do with the code...
Low voltage, current limited control circuits can.. and have...
generated all kinds of havoc when run in close proximity to branch
conductors that might induce voltage into the control line.
Contactors can 'mysteriously' pick-up at odd times, OD temp. sensing is
screwed up, solid state controls will go absolutely wack-o.
Jake

Thank You Jake. Absolutely correct. Line voltage and low voltage in
the same conduit or sealtite is a problem waiting to happen.
Im glad you explained it in very simple terms.
Bubba

sure would be nice if the ductless-mini-split manufacturers climbed on
board. seems like they're all running Hi & low volts in the same
umbilical cord....of course, WTF do they know....

Fish, Ive put in a ton of Sanyos. Two power wires up to the condenser
and three wires down to the evap. All line voltage.

[dreamchaser]

I must apologize to Noon-Air for my remark in this post. I'm sorry but
the beginning tone of Noon-Air's first post hit me like, "If you were
a HVAC contractor with all the right skills etc, you wouldn't be
asking these questions and you shouldn't do this stuff yourself"

There isn't a thing wrong with the OP replacing his own heat pump.
Obviously if this person has the audacity and brevity to take on
replacing a heat pump, he must have some experience at it or is just
down right crazy, one of the 2, I assumed the former.

As to my background and profession, I'm on my 4th career. Electrician
doing commercial and gov't work, many military bases by the way, for
12 years. Then 8 years as a Plant Engineer with a large Computer
company, Control Data where I trained and became proficient at chilled
water systems, split systems, fire alarm, UPS(solid state and motor
generator). Then on to working for a computer company installing
highly sophisticated computers with fairly complex r22 cooling and
large condensing units. Also have taken courses on Electrical
Grounding of Communications Equipment, Grounding and Lightning
protection, Piping Design related to cooling/refrigeration
equipment...So I am speaking from some experience here. that's not
really the point though.

The fact is I have spent most of my career either as a contractor or
managing contractors on projects. I recently had a new home built
which again involved dealing with contractors. The bottom line is I
don't trust contractors any further then I can throw them or the
specifications they've signed up to adhere to. My latest experience
with contractors building my home was an absolute nightmare. Fact is
they were anything but skilled, in too big of a hurry to do anything
right and really didn't give a damn. And the fact is that with my life
experiences and Engineering abilities, I know how something should be
built or installed, at least in the areas I have expertise and
knowledge and there is almost no problem I've had in my life that I
haven't fixed myself including rebuilding 3 car motors, 2 automatic
transmissions and a host of other auto/truck repairs, plumbing,
electrical, air conditioning, heating, ceramic tile. ..

In summary, I don't think anyone should be so proud of what they do or
who they are that they don't leave room for someone else to take on a
project. Have at it, learn something, save some money, feel proud of
what you've done.I will post from time to time on this newsgroup and
you will never see me offer an opinion that would endanger someone. AS
a matter of fact, to the contrary, I will defer rather then comment at
all if I can tell someone is in over their head.

Incidentally, the issue with noise coupling between the tstat wiring
and the power is for real. On that note alone, it's worth keeping the
lines separate.

[Bud]

Post by dreamchaser
There isn't a thing wrong with the OP replacing his own heat pump.
Obviously if this person has the audacity and brevity to take on
replacing a heat pump, he must have some experience at it or is just
down right crazy, one of the 2, I assumed the former.

I agree 100%. If the OP wants to replace his HVAC equipment then more
power to him. I re-read his OP and he did not proclaim to be an
experienced tech.

He's obviously seeking answers to some of the finer points of the
installation process which suggests he wants to learn and do it right
and in doing so save money and potentially get a better install by
avoiding some of the professional hacks out there.

Why is the industry so terribly affraid of DIY?? Some think a DIY
install is like stealing money from their own pockets!!

[Noon-Air]

Post by Bud

Post by dreamchaser
There isn't a thing wrong with the OP replacing his own heat pump.
Obviously if this person has the audacity and brevity to take on
replacing a heat pump, he must have some experience at it or is just
down right crazy, one of the 2, I assumed the former.

I agree 100%. If the OP wants to replace his HVAC equipment then more
power to him. I re-read his OP and he did not proclaim to be an
experienced tech.
He's obviously seeking answers to some of the finer points of the
installation process which suggests he wants to learn and do it right
and in doing so save money and potentially get a better install by
avoiding some of the professional hacks out there.

you get a better install by doing your homework and *not* purchasing a new
comfort system by price alone. Its not about *JUST* saving money, or DIY,
its about laws, codes, warrantees, liability, safety, well being, comfort
and indoor air quality. There are many reasons that codes, and code
enforcement exist. 99.99% of laws, codes, and regulations(no matter how
ignorant sounding) are only in place because somebody actually DID IT with
the resulting loss of life, limb, and/or property.
If price alone was the case when buying a car, *most* of the uninformed
public would be driving the likes of a Geo Metro. There is no one vehicle
that will meet the needs of all of the people, likewise, there is no single
comfort system that will meet the needs of every home.
This is an investment that right, wrong, or indifferent, you will have to
live with for the next 18-20 years(maybe).

Post by Bud
Why is the industry so terribly afraid of DIY?? Some think a DIY
install is like stealing money from their own pockets!!

I'm not afraid of DIY, only the results of said DIY. you can pay me to do it
right for you the first time, or you can pay a hell of a lot more to have me
do it over.
The attached link shows pics from a hacked in air handler....but they got a
Trane!!
http://new.photos.yahoo.com/noon_air/album/576460762352202314

This is what it looks like now($1800 later) after I had to completely
uninstall and re-install it.
http://new.photos.yahoo.com/noon_air/album/576460762367797999

Now, its up to you... do you want to get it done cheap, DIY or by the lowest
bidder???,
Or do you want to get it done by a *competent*, licensed, insured,
professionally trained, HVAC technician???

FWIW, after the reinstall on this system, their electric bill dropped over
60%!!!

Its you money, you can do what you want.... just remember, either way, your
going to have to live with the consequences of you decision for a long, long
time.

[Bud]

Post by Noon-Air
Now, its up to you... do you want to get it done cheap, DIY or by the lowest
bidder???,
Or do you want to get it done by a *competent*, licensed, insured,
professionally trained, HVAC technician???

Noon Air,
You obviously do great work and I agree with most of what you're
saying.

I guess the only point I was trying to make is that it's not a "given"
that a HVAC Tech won't produce a hack job. It happens all the time.

It's also not a given that a DIY/Homeowner can't produce an install to
the best known professional standards. It depends on the specific
homeowner and their willingness to reserach, plan and perform the
install to professional standards/codes/etc.

HVAC is not what I'd consider high on the list of what "average"
DIY'ers should take on. However it depends on the individual
situation.

[Bud--]

Post by RBM
I agree except I believe that once the class 1 conductors leave a class 1
location, they can be transitioned back to class2. For example, and air
handler built by "First", instead of running class 2 low voltage into the
unit and make connections on an isolated board, they run what appears to be
MTW out of the machine and leave tails for connection to class 2 low
voltage. Similarly, in any AC condenser, your class 2 conductors are
connected to line voltage conductors before entering the line voltage
compartment for connection to the contactor

All the compressor/condenser units I have seen have a separate wiring
compartment for connection to external class 2 wires. That sounds like
the "First" unit.

Class 2 wires can be in the same enclosure with line voltage wires when
required for connection to something like a relay. They stay class 2.
There are some rules like for separation. Factory wiring inside the unit
is covered by UL rules.

But wires can't mix in the same raceway. Then they become class 1.

--
bud--