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Running electrical conduit close to B vent?

ChrisJ
ChrisJ Member Posts: 15,442
edited December 2016 in THE MAIN WALL
Hey guys,
Starting to actually get into the A\C project and my plans are to run my lineset up along side my B vent via some grey plastic electrical conduit. I felt once I get the conduit in place it will make running the lineset easier, it'll also make it replaceable without swiss cheesing my walls.

Right now, one section of this is filled with spray foam, the rest is packed with rotten cotton. I'll be fixing most of that and sealing it better after I run my plastic conduit.

My question is, am i violating any codes by cutting into this and running my conduit this close to the B vent spacers?

These pictures are from when the chimney was torn down and the B vent installed before closing everything in.
Hopes are a 2" or 2.5" conduit for the suction line, another smaller one for the liquid line and a third and fourth for electrical, one for low voltage like coax, and one for 2 or 3 romex lines. Speaking of, does anyone know if romex needs to be de-rated if run inside a conduit?


If I can get some romex up there I'll finally be able to have a networked smoke detector in the attic. There's 3 floors, but two pictures should be enough as the run into the attic is simple enough.

The red lines mark where I'd like to cut.

















Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
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Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,905
    Contact your local AHJ on this one. Codes vary.

    However, I notice a problem which I would fail immediately: no firestopping at the floor levels. If I saw that, you would never get a CO from me!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JUGHNE
    JUGHNE Member Posts: 11,021
    I believe it is stated that B-vent should be 1" from combustibles.
    Your B-vent spacers/supports establish that clearance.
    PVC is considered combustible as the wood around your spacers. I always wrapped the B-vent in the attic with fiberglass insulation to keep the cellulose (said to be non combustible, but not) away from the pipe.

    Several romex stuffed into a PVC thru 2 floors are supposed to be de-rated, but it depends upon the load they are carrying. The 14-3 for the smoke detectors carries about nothing. The 12-2 for your air handler carries very little. If that was all you put into a 1 1/2 or 2" conduit, I wouldn't worry about.....if you run 10-2 for the AH and thought of it as 12-2 then it would be de-rated. I always plug the top of a pull pipe with FG to prevent air flow/condensation.
    Your low voltage could go in with the liquid line pipe. T-stat wire and 18-2 to AC together.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442

    Contact your local AHJ on this one. Codes vary.

    However, I notice a problem which I would fail immediately: no firestopping at the floor levels. If I saw that, you would never get a CO from me!

    What would you consider fire stopping?

    We jammed a ton of rotten cotton in those openings before closing everything up. We felt that would stop any air from being drawn between floors.

    As I said in my first message, I plan on improving this while I have things open again. I want those gaps filled and I plan on using spray foam to make them air tight.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Jamie's point is the openings on either side of your B-vent support. Those should be closed up with solid lumber I believe.

    You can get fire stopper foam/caulk that would/should meet code requirements. Some types expand with fire and seal the openings air tight as the pipe foam and wire insulation burn/melt.
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442
    edited December 2016
    JUGHNE said:

    Jamie's point is the openings on either side of your B-vent support. Those should be closed up with solid lumber I believe.

    You can get fire stopper foam/caulk that would/should meet code requirements. Some types expand with fire and seal the openings air tight as the pipe foam and wire insulation burn/melt.

    The local inspector was perfectly happy with the rotten cotton.
    I was not, I hate the stuff, can't stand touching it.

    I'll do what I can to totally close that off with something better. Fire aside, I don't need a draft going through there anyway.

    I used this stuff on the one on the first floor, and then through research found it's apparently no different than the normal Great Stuff, it's just red colored and quite flammable, even dry. Wasn't impressed.


    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 15,442
    @Jamie Hall Am I understanding correctly that you see no issues with what I want to do, assuming I get everything properly sealed between floors?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jamie Hall
    Jamie Hall Member Posts: 22,905
    ChrisJ said:

    @Jamie Hall Am I understanding correctly that you see no issues with what I want to do, assuming I get everything properly sealed between floors?

    That's about it. And @JUGHNE 's right -- solid wood or fire blocking foam. I don't like the idea of the rotten cotton!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442

    ChrisJ said:

    @Jamie Hall Am I understanding correctly that you see no issues with what I want to do, assuming I get everything properly sealed between floors?

    That's about it. And @JUGHNE 's right -- solid wood or fire blocking foam. I don't like the idea of the rotten cotton!
    I'm a bit confused by this, though do appreciate both your input and @JUGHNE 's.

    Rotten cotton (mineral wool) as far as I know, is often used as fire stop material. I believe it's also a bit more fireproof than wood and especially than most firestop foams, especially GreatStuff.

    This is why we used it. We had it on hand, were told it was very often used to stuff holes where firestopping was required and the inspector liked it.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    I believe code requires a sheet metal fire stop tightly fit to the pipe and covering all flat surface at floor penetration within the chase, and have even had some AHJ's require intumescent fire caulking where flashing meets B vent.

    What you currently have would cause accelerated flame spread into the vertical chase during a fire. (drafting)

    I'd ask Harvey or Kurt (both licensed electricians) your question. There are certain operating temperature limitations and a need for free air cooling based on connected load, conductor size etc. If the wires can't shed heat under load, they will get hot and can fail.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    ChrisJ
  • Jamie Hall
    Jamie Hall Member Posts: 22,905
    Ah. Now I see what you are referring to. Yes, mineral wool would be acceptable, provided it's anchored in some way to keep it from falling out -- perhaps something as simple as quarter inch hardware cloth below it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442

    Ah. Now I see what you are referring to. Yes, mineral wool would be acceptable, provided it's anchored in some way to keep it from falling out -- perhaps something as simple as quarter inch hardware cloth below it.

    Ah ok I understand.
    That's why I was confused, I probably should've posted pictures of after the mineral wool was added, but I thought these would be better for what I'm trying to do. Sadly, it caused more confusion.

    Like I said though, I plan on changing things. I'm tired of the stuff falling down on me when I try to do anything, there's plenty jammed in the areas, but it's nasty stuff.

    Do you have an expanding foam you would recommend being Greatstuff seems to be not so great?

    @Mark Eatherton Thank you for commenting.
    Please see other comments regarding mineral wool we filled those gaps with. There's no way I would've left those gaps there. As I said though, I want to improve that as well as I hate the stuff. I'm thinking some wood combined with a good fire retarding spray foam.


    @Harvey Ramer
    Do you have any thoughts on my plastic conduit idea? If I have a run of 14-3 and 14-2 romex inside grey plastic conduit in this area for two floors, would I need to derate? Also, would there be any code violations?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    Mark Eatherton
  • ChrisJ
    ChrisJ Member Posts: 15,442
    edited December 2016
    This is the only "after" picture I have showing some of the mineral wool and wood blocking


    There's practically no gap under the wood on the one side and what gap there was, was filled , and the other is packed with mineral wool as well.


    I'll be cutting the drywall out of the edge of the closet next to the B vent to run my conduits. After that, I'll be running a 10" round duct near it, but in the closet. That will need to be sealed as well.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    The reasoning behind solid lumber is that with a fire on one floor, if it were to flash over/back draft, there is enough air or steam pressure generated to blow out the loose fill. (windows for sure).

    One memorable basement fire I worked was contained with-in minutes. However there was a 16 X 20 access panel behind the bathtub faucet that was not screwed down. That in conjunction with a 12 x 12 floor hole for the CI tub drain allowed enough heat and smoke to total the main floor. All water damage was limited to the basement.
    Also at that house the SA was wall stack ducts installed in the inside walls. Of course to get the 3 1/4" X 12 duct in you cut out the entire bottom plate of the wall. The fire was headed up inside those cavities from the basement thru the extra 1" on either side of the duct.

    Lack of 2 screws on the wall panel cost the homeowners a lot of grief and the insurance company a lot of money.
    ChrisJCanucker
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Chrisj, the 2014 NEC Code book, (know as the big book of exceptions), implies raceway for physical protection of NM Romex cable shall be steel or if PVC to be SCH 80. Then cables must be de-rated for current carrying capacity. The threshold is 2 or less cables, after that it gets more involved. (run 2 pipes if more is needed??)

    Some may agree with me that rather than chase thru the 310-10 section of the NEC to determine the ampacity to just increase your 14 gauge conductors to #12 and connect them to 15 amp CB's.

    This is a situation where 3 different AHJ's will give you 5 different answers. IMO
    Mark EathertonChrisJSolid_Fuel_Man
  • ChrisJ
    ChrisJ Member Posts: 15,442
    JUGHNE said:

    Chrisj, the 2014 NEC Code book, (know as the big book of exceptions), implies raceway for physical protection of NM Romex cable shall be steel or if PVC to be SCH 80. Then cables must be de-rated for current carrying capacity. The threshold is 2 or less cables, after that it gets more involved. (run 2 pipes if more is needed??)

    Some may agree with me that rather than chase thru the 310-10 section of the NEC to determine the ampacity to just increase your 14 gauge conductors to #12 and connect them to 15 amp CB's.

    This is a situation where 3 different AHJ's will give you 5 different answers. IMO

    I Googled this assuming it wouldn't exist.

    And yet, there they are!





    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Yes, the odd ducks do exist. Did you get a cost for those?

    However, for the smoke detector circuit, I always put some obvious lights on with that circuit. The thought is that if all batteries were removed and the CB off there would be some key lights not working and get the HO off the couch to rectify the situation. (That way the EC went above and beyond the requirements to keep the SD on line)
    And also you might have AFCI CB's for the SD circuit or technically by the letter of the law when you extend a circuit that circuit may have to be upgraded to AFCI. :o
    It just doesn't end does it. How did we survive this long?

    I would consider #12 for the AH regardless of the nameplate.
    Wait, there may be more. HVAC equipment in an attic is required to have lighting and a GFCI outlet available.
    (Maybe not in the code book but is in my common sense list)

    If you run 12-3 to the attic connected to a 2P 20 amp CB, you can use one hot and the white neutral for an outlet. Then after the outlet the 2 hots go into your AH disconnect.
    I have done this for ACU's that only need a 20 amp CB and also the required GFCI outlet at unit. (Of course I only put in 2 Ton AC's ;) )
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442
    JUGHNE said:

    Yes, the odd ducks do exist. Did you get a cost for those?

    However, for the smoke detector circuit, I always put some obvious lights on with that circuit. The thought is that if all batteries were removed and the CB off there would be some key lights not working and get the HO off the couch to rectify the situation. (That way the EC went above and beyond the requirements to keep the SD on line)
    And also you might have AFCI CB's for the SD circuit or technically by the letter of the law when you extend a circuit that circuit may have to be upgraded to AFCI. :o
    It just doesn't end does it. How did we survive this long?

    I would consider #12 for the AH regardless of the nameplate.
    Wait, there may be more. HVAC equipment in an attic is required to have lighting and a GFCI outlet available.
    (Maybe not in the code book but is in my common sense list)

    If you run 12-3 to the attic connected to a 2P 20 amp CB, you can use one hot and the white neutral for an outlet. Then after the outlet the 2 hots go into your AH disconnect.
    I have done this for ACU's that only need a 20 amp CB and also the required GFCI outlet at unit. (Of course I only put in 2 Ton AC's ;) )

    AFCI?
    In my house? I don't think so Tim. :)

    Speaking of lighting though, I do plan on installing much better lighting up there as well as a few receptacles. Right now there's just one hardwired light and that's not near enough. Especially if I need to be able to service an air handler.

    The 10A CBs were around $17 or so I think. Much more than a 15 or 20 at Homer.

    My hard wired smoke detectors I believe are wired into the basement lights if I remember correctly. I don't think that feeds anything else. That was run in 1987 after a fire in the house, funny thing, when we moved in all of the smoke detectors were battery only, sitting over the plugs. I pulled them all down and installed networked ones again. If the one in the basement goes off I want to be able to hear it on the 2nd floor in my bedroom. They did 3, one for each floor but none in the attic and I don't care for that, especially with equipment being installed up there.

    I'm slowly switching them over to combination CO/Smoke units as well.



    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    IIWM, and I considered adding more electrical load I would probably run 2 lengths of 3/4" EMT up the chase and pull individual #12 THHN copper conductors between J-boxes in basement & attic. 3 circuits easy in one pipe. One pipe for future?
    Solid_Fuel_Man
  • ratio
    ratio Member Posts: 3,603
    Don't scoff at the AFCI breakers. I actually have, in my garage, a piece of MC jacket with a tiny pinprick burned through the aluminum, along with the three now bare copper conductors that were inside it when we opened the wall to find out what was on fire. You can tell the hot wire due to the tiny crater melted in it by whatever mfgr'ing flaw caused the problem—no mechanical damage to the sheath within 3' of the center of the burned area.

    And a run or two of EMT is the way to go, although with the way the Code is now WRT derating and sharing neutrals, you might be better off with individual pipe runs too.

  • ChrisJ
    ChrisJ Member Posts: 15,442
    ratio said:

    Don't scoff at the AFCI breakers. I actually have, in my garage, a piece of MC jacket with a tiny pinprick burned through the aluminum, along with the three now bare copper conductors that were inside it when we opened the wall to find out what was on fire. You can tell the hot wire due to the tiny crater melted in it by whatever mfgr'ing flaw caused the problem—no mechanical damage to the sheath within 3' of the center of the burned area.

    And a run or two of EMT is the way to go, although with the way the Code is now WRT derating and sharing neutrals, you might be better off with individual pipe runs too.

    Perhaps things have changed, but all I've ever heard of is constant nuisance trips to the point where no one even looks for a fault after the first week.

    Has this improved?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ratio
    ratio Member Posts: 3,603
    Maybe you're thinking of GFCIs? They were bad for that the first few generations, noticeably better now though. I installed three Homeline combo arc/ground fault breakers at my brother's place next door for durable medical equipment, haven't heard about any problems yet. (Also got some tamper resistant hospital grade recepts with power indicator LEDs on 'em. Very nice, but Good Golly! were they proud of them.)

    Not that I necessarily think they're so great that they should be installed everywhere, but the faults that they're supposed to catch actually exist.

  • ChrisJ
    ChrisJ Member Posts: 15,442
    ratio said:

    Maybe you're thinking of GFCIs? They were bad for that the first few generations, noticeably better now though. I installed three Homeline combo arc/ground fault breakers at my brother's place next door for durable medical equipment, haven't heard about any problems yet. (Also got some tamper resistant hospital grade recepts with power indicator LEDs on 'em. Very nice, but Good Golly! were they proud of them.)

    Not that I necessarily think they're so great that they should be installed everywhere, but the faults that they're supposed to catch actually exist.

    No, definitely thinking of arc faults.

    Hospital spec receptacles connected to Homeline breakers.
    Am I the only one seeing a problem there? :)

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ratio
    ratio Member Posts: 3,603
    I standardized on Homeline because I was tired of guessing on what breakers I needed to take with me when I had to do something for family. (I think there's only one or two panels left that I need to change out.) And hospital grade because, well, durable medical equipment.

    Pretty sure that when I get around to doing the backup generator it's going to be around 30 kW. Go big or go home. Or both. ;)

  • ChrisJ
    ChrisJ Member Posts: 15,442
    ratio said:

    I standardized on Homeline because I was tired of guessing on what breakers I needed to take with me when I had to do something for family. (I think there's only one or two panels left that I need to change out.) And hospital grade because, well, durable medical equipment.

    Pretty sure that when I get around to doing the backup generator it's going to be around 30 kW. Go big or go home. Or both. ;)

    Ah.
    Personally, I swear by QO and it's the only thing I'll use.

    I tend to stick with commercial grade receptacles and switches, though also like the hospital stuff as well.

    I like a good, solid loud toggle switch. Have never trusted the silent ones that don't give a good solid click. I've seen them get left partially on and arcing years ago. The rocket style ones are nice too, but cosmetically I prefer toggle.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ratio
    ratio Member Posts: 3,603
    Yah, well, bolt-on breakers are my preferred style... ;););)
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 15,442
    ratio said:

    Yah, well, bolt-on breakers are my preferred style... ;););)

    Cartridge fuses or go home.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Probably with romex connecting the outlets to Homies. :)

    AFCI technology has improved a lot since first being introduced.

    I had more problem with smoke/CO combo devices than either AFCI or even older GFCI.

    Neither of these methods can utilize a shared neutral.
    Your 240/120 circuit would always be on a standard circuit breaker, with a GFCI device at POU.

    Someday you or next owner will have to upgrade the panel board. Today if it stays where it is you will not have to add the AFCI/GFCI requirements. However extend any existing circuit 6' or more of conductor and all the new goodies come into play.
    (Says my AHJ anyway). So any wiring you may add now should be done correctly and connected to your existing panel. This will save you some grief if a EC upgrades the service. IMO
    The next code comes out in 2017 and will have more requirements for AFCI than the 2014.

    I put the AFCI/GFCI CB's in a house that was badly wired in the 1950's. Crossed my fingers and haven't had a call in 2 years.
    Lady is 90+ years and would not reset anything herself.
    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 11,021
    ITE Bulldog Pushmatics are considered bolt on CB.....do you need some?? NIB-USA
  • ChrisJ
    ChrisJ Member Posts: 15,442
    JUGHNE said:

    Probably with romex connecting the outlets to Homies. :)

    AFCI technology has improved a lot since first being introduced.

    I had more problem with smoke/CO combo devices than either AFCI or even older GFCI.

    Neither of these methods can utilize a shared neutral.
    Your 240/120 circuit would always be on a standard circuit breaker, with a GFCI device at POU.

    Someday you or next owner will have to upgrade the panel board. Today if it stays where it is you will not have to add the AFCI/GFCI requirements. However extend any existing circuit 6' or more of conductor and all the new goodies come into play.
    (Says my AHJ anyway). So any wiring you may add now should be done correctly and connected to your existing panel. This will save you some grief if a EC upgrades the service. IMO
    The next code comes out in 2017 and will have more requirements for AFCI than the 2014.

    I put the AFCI/GFCI CB's in a house that was badly wired in the 1950's. Crossed my fingers and haven't had a call in 2 years.
    Lady is 90+ years and would not reset anything herself.

    Understood.
    Though, I'd hope there would be no upgrading necessary for a long long time.

    I've got a 20 pos QO panel with a 8 pos QO subpanel. 100A service which was tight when the house had electric appliances but since ditching all of those it's been pretty nice.

    Worse case scenario I see is having to swap in all double lever breakers into the sub panel. For whatever reason, the main panel doesn't support them.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 11,021
    The main breaker panel is a 20 space or circuit only. Your pony panel may accept the tandem CB. I have learned to not use them when possible because of overcrowding in that 8 space subfeed panel.

    IIWM, I would change out the 8 space to at least a 30 space main lug only panel. It may be fed by a 60 amp breaker, although the new MLO will be rated at 125A max. Get full size breakers. If the main service is ever upgraded, then the sub feed could stand on its own with out upgrade. (2014 code anyway).
    I would put your ACU and AH in the main box though. I try to keep any 240 loads in the main panel.

    Typically in a house of your size, it would get a 200A 40 circuit, service, even with gas heat and water heater. However I have had to add a 2nd 40 circuit sub-feed on a 100 amp CB. Just to have enough CB spaces. The 200 amp main is not really needed, it is just the minimal standard done in this area. But the typical 40 space panel just doesn't have enough room.
    It is not the total load, it is the number of circuits needed.

    I'm thinking for your area that the HO can do his own wiring unless the service must be changed......then a permit and EC is needed....also a bank loan.....I know, this is what I do....among other things.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Derating is a combination of many factors. Ambient temperature, number of load carrying conductors, continuous load, noncontinuous full load, insulation type, wire type, ect.. I would definitely use EMT and THHN to run through the flue chase if I did it at all. I don't know what to predict as the ambient temperature inside the chase.

    Here is a handy little calculator to figure out the derating.

    http://www.electrician2.com/calculators/wireocpd_ver_1.html

    I might find a different way up and run a 6-3 Romex up to the attic and put a small 12 space main lug panel up there. Even if you do go through the chase with EMT, I might still run the 6-3 with a small panel in the attic.

    As far as the smokes, wire them in with a light so you'll be aware if the breaker is tripped. You also might want to read up on dual sensor smokes, as they detect 2 distinctly different types of fires. http://www.asecurelife.com/best-smoke-detector/
    ChrisJ
  • Tinman
    Tinman Member Posts: 2,808
    I did new construction for 20 plus years and, it's like Mark said, metal tight to the vent and covering the chase. I've also had an electrical license since '87. I run everything inside a building in EMT and with THHN. That said, if wires are overheating in a B-vent chase and are more than an inch away, you've got much bigger problems to worry about.
    Steve Minnich
    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Your smoke detectors would let you know if THHN insulation was melting! ;)
  • ChrisJ
    ChrisJ Member Posts: 15,442
    edited December 2016
    So,

    There doesn't seem to be any complaints about running the lineset up the chase, so that's good. :)

    And, if I want, I can run THHN up through the chase as well via EMT? Can I get away with the grey PVC sch 40 conduit, or no? The only purpose the conduit serves in my mind is to keep the wires, and lineset straight and 1+" away from the B vent. Other than that, there's nothing ever going to get near them.


    Installing a sub panel in the attic is an interesting idea. I need to ponder that one for a bit. Though with individual runs I don't really need the subpanel, I could just pull more wires down the road as long as I use a large enough conduit.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Are you guys making fun of me? Lol

    I have no concern about ambient temperature in the chase melting the wires. The concern is what ambient temperature to use as a derating factor.
  • JUGHNE
    JUGHNE Member Posts: 11,021
    Electrical PVC is for sissies, Charlie would hit you with a sock full of quarters. ;)
    The span between floors will get pretty floppy. I don't want to look in the book, but maybe it should be SCH 80.
    PVC is supposed to be supported every 3'?.
    EMT every 10'.
    The expansion rate of the PVC in that chase will wiggle it around during the heating season. EMT...no problem. JMO
    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 11,021
    No Harvey, no slight intended.
    Seriously, are not the de-rating factors applied to prevent degrading of the wire insulation. (melting).
    The temp in the B-vent chase would be less than summer attic temps, IMO.
    Sometimes I feel the de-rating factors are over rated.....
    My AHJ used to say 6 conductors in a pipe, now he is comfortable with 8 before you would have to run #10 for a 20 amp circuit.........I just go with the flow.
    The requirement for multi wire branch circuits having to be on a 2 or 3 pole CB has changed a lot. Don't want 2 or 3 circuits tripping when one overloads.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    They are overrated most of the time.

    Most circuits aren't anywhere near max capacity most of the time. However, for example, lighting circults in large buildings are almost always running near max load. Get to many of those in a conduit without derating and it will start humming like a nest of angry hornets and the pipe will get hot. A buddy electrician made that mistake.

    It's also something to be aware of when running parallel conductors for large amperage services in commercial applications.

    To much heat exposure over a period of time will also cause cracking in the insulation.

    I doubt Chris will have any problem in his application but rules are what they are. Who knows what the next owner will install or do with it.

    My OCD like everything to be in its own compartment even when it doesn't make sense.
    ChrisJ
  • JUGHNE
    JUGHNE Member Posts: 11,021
    I started with a 1965 code book, the only expired one that I keep.
    The changes in this field have been enormous. But to most people they still have the same lights and outlets.
    Protection of personal and property has been vastly improved. No matter how much we as EC have kicked and screamed.

    The Code has seemly been made unwieldy...maybe it is my age?
    Micro calculations of pipe fill has doubled or tripled tables for just that matter alone.

    Why isn't AC and MC just made into one cable? Call it MAC. The differences have added maybe 20 pages to the code.

    But having taken down light fixtures that were mounted to J-boxes and seeing the damage to insulation from even 1970 installations with plastic sheathed Romex....before NM-B was introduced. (Which is now just NM).
    The damage done by just 3 75watt bulbs is considerable. Who would have thought that that heat would be conducted by the copper leads themselves back to the wire nuts (lets not forget Buchannan's or soldered) and all cables.
    What seems to be a little heat goes a long way. If anyone doubts this just put a lighted 75 watt bulb in your pants pocket for what I guarantee will be a short time. This clearly demonstrates the inefficiency of incandescent bulbs and their load on cooling systems.
    I have pulled a 1980's 14-2 romex cable out from under 10" of insulation that was shorted/arcing enough to dim the lights in the building and start the insulation on fire. That cable had ended up on a 20 amp CB and was peaked out close to 20 amps. This would be a prime case for a AFCI as it was not tripping the CB but arcing and producing enough energy to ignite the flame resistant cellulose insulation. Christmas lights on the local Griswald house, yes stapled on the roof just like the movie. Today he would have LED's.

    Buying light bulbs today is almost like picking out paint colors. Such a range of K numbers. 10 years ago no one had ever heard of that.

    O well my rant is over, for now anyway .
    Solid_Fuel_Man
  • ChrisJ
    ChrisJ Member Posts: 15,442
    edited December 2016
    JUGHNE said:

    I started with a 1965 code book, the only expired one that I keep.
    The changes in this field have been enormous. But to most people they still have the same lights and outlets.
    Protection of personal and property has been vastly improved. No matter how much we as EC have kicked and screamed.

    The Code has seemly been made unwieldy...maybe it is my age?
    Micro calculations of pipe fill has doubled or tripled tables for just that matter alone.

    Why isn't AC and MC just made into one cable? Call it MAC. The differences have added maybe 20 pages to the code.

    But having taken down light fixtures that were mounted to J-boxes and seeing the damage to insulation from even 1970 installations with plastic sheathed Romex....before NM-B was introduced. (Which is now just NM).
    The damage done by just 3 75watt bulbs is considerable. Who would have thought that that heat would be conducted by the copper leads themselves back to the wire nuts (lets not forget Buchannan's or soldered) and all cables.
    What seems to be a little heat goes a long way. If anyone doubts this just put a lighted 75 watt bulb in your pants pocket for what I guarantee will be a short time. This clearly demonstrates the inefficiency of incandescent bulbs and their load on cooling systems.
    I have pulled a 1980's 14-2 romex cable out from under 10" of insulation that was shorted/arcing enough to dim the lights in the building and start the insulation on fire. That cable had ended up on a 20 amp CB and was peaked out close to 20 amps. This would be a prime case for a AFCI as it was not tripping the CB but arcing and producing enough energy to ignite the flame resistant cellulose insulation. Christmas lights on the local Griswald house, yes stapled on the roof just like the movie. Today he would have LED's.

    Buying light bulbs today is almost like picking out paint colors. Such a range of K numbers. 10 years ago no one had ever heard of that.

    O well my rant is over, for now anyway .

    When I was in highschool in the late 90s I was over a good friend's house playing NFS 5 Porsche Unleashed. I packed up and got ready to head home sometime around 2 or 3 AM. We were standing in his parent's livingroom and the lights went out, but only in that room.

    He said "huh, that's odd" and then they came back on. I told him he better look into it, that's not right.

    A few years later they had me come over, it was an emergency.

    A leak, had been leaking water into the electrical panel and it caused the neutral going to the livingroom to corrode and arc. It burned the neutral all the way up the wall.

    That was a good case for an arc fault.
    Then again, it was a good case for many things.

    I went to Votech, in the end for electrical work. Problem is I never really used it outside of my own stuff and that was a long time ago.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment