Liquidtite conduit application?

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  #1  
Old 02-27-14, 03:52 PM
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Liquidtite conduit application?

I need to take power out to my AC.

Right now in 1/2 emt, there is #10 thhn solid (black red green). It goes into a 4x4 box about a 1-2' from the sill plate of my basement. I was going to pass thru that box without splicing the conductors, they would just transfer into 1/2 liquidtite.....

Is it appropriate to use liquidtite thru the house/sill plate siding?

What would be the proper method for bringing it outside?

What fitting do I need to connect liquidtite to 4x4 box and to disconnect outside?

I see premade whips but they are only 6 ft, I was going to buy 25' so I have plenty to work with....
 
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  #2  
Old 02-27-14, 04:41 PM
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You will need two liquidtight connectors. They come in both straight and 90 degree styles.

Can you come straight into the back of the disconnect?
 
  #3  
Old 02-27-14, 08:53 PM
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Liquid Tight Conduit

If you cannot get into the back of the A/C disconnect you could go out through the mud sill and install an LB condulet and then run EMT up to the disconnect. Then install the liquidtight flex to the condenser. If you don't exceed the support lengths, depending on the type of flex you use, the flex connectors are approved as support for the flex. Name:  HVAC.jpg
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  #4  
Old 02-28-14, 03:35 AM
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Thanks for that diagram, that's the exact situation however, the junction box is on a joist about 2' from the sill plate.

Theres already a liquidtite whip between disconnect and condenser.

I cannot come in thru the back of the disconnect. There is currently a UF cable that exits the house with the lineset. It exits the house about 3 ft from the disconnect and enters the disconnect thru the bottom left knockout.

So bringing another liquidtite flex from the junction to the outside is not proper, I need an an LB and keep it all rigid up to the disconnect?

I am also not clear about fittings which I assume have to be watertight compression fittings?
 
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Old 02-28-14, 06:03 AM
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Doesn't the UF currently feed the disconnect?

The fitting need to be for the wiring method used.

You do not need rigid. You could use PVC.
 
  #6  
Old 02-28-14, 10:32 AM
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Liquidtight Conduit

As mention by pcboss you can use pvc. You have wiring to your j-box, so run PVC out to a PVC LB and up to the disconnect. The PVC will allow for a better building penetration since it will be fixed. The LB will keep the conduit close to the building surface for securing. Flex is meant to be used where vibration is an issue not to mention PVC will be a lower cost.
 
  #7  
Old 02-28-14, 11:53 AM
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Do I have to do anything different in relation to grounding if I connect PVC to the metal junction box on the interior? What fittings are used for pvc to 1/2" knockout?

The penetration will be thru wood, foam insulation then vinyl siding, the LB would be mounted. I assume I would use 1/2 grey pvc which is glued like drain pipe. 3/4 or 1/2 - AC is 3 x #10?

And to make bends into the bottom of the disconnect would I be heating and shaping the pipe or do I need to use exact measurements and fittings?

Also should I be splicing in the junction box or LB? OR can I just pass right thru the both of them directly to the disconnect?
 

Last edited by cws05; 02-28-14 at 01:13 PM.
  #8  
Old 02-28-14, 01:15 PM
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Pvc

Do I have to do anything different in relation to grounding if I connect PVC to the metal junction box on the interior? What fittings are used for pvc to 1/2" knockout?
Fittings would be two Male Adapters with locknuts, one at the j-box in basement and one in bottom of A/C disconnect.
The penetration will be thru wood, foam insulation then vinyl siding, the LB would be mounted. I assume I would use 1/2 grey pvc which is glued like drain pipe.
The PVC will be glued at the LB and any couplings you need. If your LB is not under the disconnect , you can run conduit in the direction of the disconnect and use a PVC 90-deg elbow to turn up where you need to be. If your real close you can angle the LB at 45-deg and then use a PVC 45-Deg bend to get under the disconnect.
Also should I be splicing in the junction box or LB? OR can I just pass right thru the both of them directly to the disconnect?
Do not splice in the LB. You already have a j-box, so make your splice there and pull your THWN-CU conductors through the LB and terminate in the disconnect. You need to install a Green grounding conductor in the PVC and terminate it in the disconnect and j-box to bond them together. Do not use sheet metal screws for that. The 4S box should have a threaded screw hole for a ground screw and the disconnect should have a place for a ground.
 
  #9  
Old 02-28-14, 05:25 PM
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So 1/2" better than 3/4"?

Locknut metal with the pvc? No compression/watertight connection at disconnect? Just the locknut?


Do I need any additional bushing for the pvc male adapters?

I don't think ever say electircial pvc elbows? So I should be shaping the pipe to fit?

My AC has green ground that runs back to the panel... I assume you mean theres should be a grounding screw hole in the body of the disconnect? If so, #14 there?

As for the ground (EGC) of the AC that runs back to the panel... does that have to be #10 too? Or can I run #12 back to the panel for the ground?

Why is it better to splice in the junction box inside rather than looping the conductors through?

Sorry, lots of questions of the top of my head....
 
  #10  
Old 02-28-14, 05:57 PM
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Pvc

If the wire you have is long enough and rated for wet location (outside conduit) then you do not need to splice. Wire should be #10 THWN-CU. The Equipment Ground that will go in with the circuit conductors runs from the j-box to the disconnect and needs to be Green #10 THWN-CU. The EMT conduit you have from the panel to the J-box is the ground for that part of the run. If there is a Ground in the EMT then it should be bonded to the j-box also. 1/2"PVC Sch-40 can hold (5) #10 THWN-CU so should be ok. If you have a way to heat the pvc without burning it, you can bend it, otherwise the supply house should have PVC bends in stock. Yes you can use metal locknuts on the PVC Male Adapters. No bushing is required for the size circuit conductors you are installing. PVC MA at bottom of disconnect is considered raintight. If you enter the side of the disconnect you would need a sealing locknut to make it raintight.
 
  #11  
Old 03-03-14, 04:24 PM
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What about a union? How do I remove the glued conduit?
 
  #12  
Old 03-03-14, 04:49 PM
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A/c

What about a union? How do I remove the glued conduit?
What glued conduit? Not sure what your wanting to remove. New PVC from j-box to LB and from LB to disconnect will be glued.
 
  #13  
Old 03-03-14, 05:11 PM
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If you had to remove the length from the junction to the lb or lb to the disconnect? Once I glue the male adapters to the pvc its cemented in place?
 
  #14  
Old 03-03-14, 05:41 PM
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A/c

If you had to remove the length from the junction to the lb or lb to the disconnect? Once I glue the male adapters to the pvc its cemented in place?
Once you install the conduit, not sure why you would want to remove it but if you needed to, just disconnect the wire, pull it out, back to the j-box and remove the locknuts, and pull the pipe off. If the pipe won't come free from the disconnect, cut it below the disconnect. If you then need to replace the pipe just use a single coupling to put it back together.
 
  #15  
Old 03-04-14, 05:15 PM
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There is a PVC fitting, called something like a 1/2 to 3/4" bushing reducer.

Is that simply a reducer that I can glue to make that transition? I ask because the ones I was trying out weren't as snug as normal pvc fittings.

Also in regards to bonding the disconnect to the junction box inside (PVC between the two). Do I have to use the same size ground wire as the conductors? Or can I simply use a #14?
 
  #16  
Old 03-04-14, 07:05 PM
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There is a PVC fitting, called something like a 1/2 to 3/4" bushing reducer.

Is that simply a reducer that I can glue to make that transition? I ask because the ones I was trying out weren't as snug as normal pvc fittings.
I've run into that too. Turns out they're fine once they're glued.

Why do you need a reducing bushing? Why can't you run either 1/2" or 3/4" all the way?

Do I have to use the same size ground wire as the conductors? Or can I simply use a #14?
Originally Posted by bahtah
The Equipment Ground that will go in with the circuit conductors runs from the j-box to the disconnect and needs to be Green #10 THWN-CU.
Right now in 1/2 emt, there is #10 thhn solid (black red green). It goes into a 4x4 box about a 1-2' from the sill plate of my basement. I was going to pass thru that box without splicing the conductors, they would just transfer into 1/2 liquidtite...
The two ungrounded conductors can be pulled straight through. The metal 1900 box needs to be bonded to ground. You need to either cut that conductor and splice it back together with a ground tail to the box or strip 1" or so of insulation off of it, without cutting it, and crimp the bare section around a ground screw in the box.
 
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Old 03-05-14, 02:38 AM
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Why do you need a reducing bushing? Why can't you run either 1/2" or 3/4" all the way?

The knockout in the disconnect I likely will need to enter in was already used and is 3/4.... As far as I can see I use the that reducing bushing with a 3/4 male adapter and locknut a amd the rest would be 1/2" (including the LB).

The two ungrounded conductors can be pulled straight through. The metal 1900 box needs to be bonded to ground. You need to either cut that conductor and splice it back together with a ground tail to the box or strip 1" or so of insulation off of it, without cutting it, and crimp the bare section around a ground screw in the box.
I apologize, I guess I am a little confused about the bonding again, isnt using two #10 green redundant?

OK so I intend to run a #10 green from a ground screw in the disconnect (I assume there would be one, unless I have to tap?) to the ground screw in the junction box inside . That bonds the two.

Then a separate #10green will be run with the conductors from the terminals on the disconnect, into the junction (where I will be splicing) and then back to the panel. There is no neutral/white of course in this. And in the panel I will be connecting this to a 30A breaker and the green will be on the neutral busbar.
 
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Old 03-05-14, 06:39 AM
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The knockout in the disconnect I likely will need to enter in was already used and is 3/4.... As far as I can see I use the that reducing bushing with a 3/4 male adapter and locknut a amd the rest would be 1/2" (including the LB).
Just use reducing washers to reduce the knockout down the 1/2".
 
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Old 03-05-14, 06:59 AM
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isnt using two #10 green redundant?
In either conduit run, yes.

Thinking of this as two runs, one green wire goes from the disconnect to the 1900 box and the other from that box to the panel. The disconnect enclosure should be bonded to the single green wire there. If all of your grounds and neutrals are bonded together on one busbar in your panel, the new ground gets terminated there.

In the 1900 box, the two green wires entering it should be spliced together with a pigtail and that pigtail is used to bond that box to ground.
 
  #20  
Old 03-05-14, 08:04 AM
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In the 1900 box, the two green wires entering it should be spliced together with a pigtail and that pigtail is used to bond that box to ground.
So if I splice all conductors in the 1900 box, the two grounds entering the box (panel side and disconnect side) will be spliced and an extra pigtail is made to connect to the 1900 box?

Im going to get this straight yet, thanks for being patient with me... Im about to start glueing my fittings right now...
 
  #21  
Old 03-05-14, 08:24 AM
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So if I splice all conductors in the 1900 box, the two grounds entering the box (panel side and disconnect side) will be spliced and an extra pigtail is made to connect to the 1900 box?
Exactly. .
 
  #22  
Old 03-05-14, 10:45 AM
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So if I splice all conductors in the 1900 box, the two grounds entering the box (panel side and disconnect side) will be spliced and an extra pigtail is made to connect to the 1900 box?
Exactly. .

But there's no reason to cut and splice the two hot conductors there, unless it's just easier to do that. They can be pulled through. Only the ground conductor needs to be cut, to enable the box to be bonded to ground.
 
  #23  
Old 03-05-14, 12:28 PM
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OK thank you, I understand now.

I just got done running the 1/2" pvc.... in a snow storm no less!! The neighbors probably think I am nuts working on my AC in the middle of winter.....

Now just need to figure out how to get a strap on it... its about 2' from the 1900 box to the sillplate.... and maybe another 2' from the LB to the disconnect.... I assume the 3' ft from box strap rule applies with RNC conduit too...



As for the unused knockout... I assume I can just use a standard knockout seal?
 
  #24  
Old 03-05-14, 01:10 PM
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Strap the outside pipe. Use a weatherproof KO blank outdoors.
 
  #25  
Old 03-05-14, 02:38 PM
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Use a weatherproof KO blank outdoors.
Ive never seen weatherproof ones... does someone have a photo?
 
  #26  
Old 03-05-14, 03:02 PM
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Just ask at the big box or the supply house. For flat metal boxes, it's basically two round plates with rubber gaskets and a bolt through the middle.
 
  #27  
Old 03-05-14, 07:56 PM
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WP KO Seal

Here is a photo of a W.P. KO Seal:

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  #28  
Old 03-06-14, 07:57 AM
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I was able to find those exact wp seals at the local supply house. I needed 2 and they cost 16 bucks!! About the same price as a new disconnect but worth it since I would have to remake my conduit at this point to put in a new disconnect....

thanks again for your help.
 
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