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Old 03-29-2012, 12:22 PM   #1
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Total Degrees of Bend in Underground PVC Conduit


I am running PVC from a hot tub GFCI disconnect panel to the hot tub control module. The conduit run will be underground. The first 90* bend will be at the bottom of the trench coming down the wall from the disconnect and heading out into the yard. There will be another 90 deg bend to turn around the far side of the hot tub. I may be able to get by with one more 90* bend to get up above grade level next to the hot tub pad where flexible conduit will be used to protect wires from that point up into the hot tub control module. However, it may be that I have to put one more 90* bend in the underground path, which would give me a total of 360* of bend before coming back above grade.

My question is do degrees of bend in the flexible conduit (which could be attached after cable comes out of the underground conduit) count against the total degrees of bend between junction boxes? If so, even if I only have 270* of bend underground if I have an "S" shaped short run of flexible conduit from above grade into the control module will this put me over the 360* maximum? I was thinking of using a 90* bend fitting on the end of the flexible conduit where it goes up into the bottom of the control module housing because it would be easier to deal with than making a tighter bend in large diameter flexible conduit.

I am planning on using the large sweeping radius elbows as opposed to tight radius elbows to accomplish the 90* turns in the conduit run. Additionally, I plan to pull the wire through sections of conduit prior to cementing the sections of conduit together to limit the length of runs and bends that wire is being pulled through all at once. As such, I wouldn't expect stress on the wire to be of consequence.

If this is going to cause issues, would it meet code to put an underground junction box of some sort in place part way through the conduit run? I know within homes junction boxes are not allowed to be covered. I wasn't sure if code would allow them strictly for wire pulling purposes as opposed to wire splice connections within conduit runs if they are going to be covered by soil.

Best Regards,

Ted Allen

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Old 03-29-2012, 12:35 PM   #2
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Total Degrees of Bend in Underground PVC Conduit


Quote:
My question is do degrees of bend in the flexible conduit (which could be attached after cable comes out of the underground conduit) count against the total degrees of bend between junction boxes?
....reconsidering if bends in FLC count against the raceway...
360 between pull points (jboxes, LBs, ect). Technically it is against code to pull wire as you are constructing the raceway and it is against code for the reason just have just described.

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I was thinking of using a 90* bend fitting on the end of the flexible conduit where it goes up into the bottom of the control module housing because it would be easier to deal with than making a tighter bend in large diameter flexible conduit.
That connector will not count against the degrees of bends.

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If this is going to cause issues, would it meet code to put an underground junction box of some sort in place part way through the conduit run? I know within homes junction boxes are not allowed to be covered. I wasn't sure if code would allow them strictly for wire pulling purposes as opposed to wire splice connections within conduit runs if they are going to be covered by soil.
It doesn't matter if the wire is spliced or runs straight thru, junction boxes must remain accessible.

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Old 03-29-2012, 12:54 PM   #3
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Total Degrees of Bend in Underground PVC Conduit


After double checking the code book, the entire raceway can only have 360 degrees between pull points. I don't see any exceptions although I can already hear the arguments.
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Old 03-29-2012, 01:11 PM   #4
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I am planning on using the large sweeping radius elbows as opposed to tight radius elbows to accomplish the 90* turns in the conduit run.
You are using the grey electrical PVC aren't you? What size?

You can set a junction box or LB where the conduit comes next to the tub. Attach the flex to it, that will give you your break.
Remember, the grounding wire to a hot tub MUST be insulated.
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Old 03-29-2012, 02:08 PM   #5
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Pulling wire in sections and then cementing joints is non-compliant. You should build the whole conduit run then pull in the wire.

This rule exists for a very good reason, the solvent in the cement can compromise the integrity of the insulation on the wire.
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Old 03-29-2012, 03:07 PM   #6
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The 360 degree limit is not just a code rule, but a practical one as well. You may not be able to actually pull the wire through that raceway. Use a pull box where the conduit comes above grade, before the flex section.
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Old 03-29-2012, 03:33 PM   #7
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You are using the grey electrical PVC aren't you? What size?

You can set a junction box or LB where the conduit comes next to the tub. Attach the flex to it, that will give you your break.
Remember, the grounding wire to a hot tub MUST be insulated.
Yes, I am using the grey electrical PVC. I was planning on using 1 inch conduit. The manufacturer (Hot Springs) installation requirements call for a total of 4 #10 AWG wires coming from a 30 amp GFCI breaker in the disconnect panel and a total of 2 #12 AWG wires coming from a 20 amp GFCI breaker in the disconnect panel. I need to perform calculations to verify that a 1" conduit will comply with NEC volume requirements within the conduit. This is a used hot tub and the previous owner had used 1" flex conduit above ground all the way from the disconnect to the hot tub, but they were in a different state and I don't know if their installation was inspected (which I am having done).

I think I will go with a LB where the conduit comes out of the ground by the hot tub base.

I also need to check with the local inspector to see if frost expansion joints are required in the PVC runs in my locale.

Best Regards,

Ted
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Old 03-29-2012, 03:49 PM   #8
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Total Degrees of Bend in Underground PVC Conduit


You will be fine on the fill....per the table....you could have up to 15 #10's in there....though I wouldn't go that many unless it was a short straight run. It's bad enough pulling that many wires through steel conduit....

Your wise going with 1"....while your at it...toss in a spare wire or pull string....you never know....
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Old 03-29-2012, 06:54 PM   #9
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Does your area require a disconnect within sight of the hot tub?
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Old 03-29-2012, 06:58 PM   #10
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You will be fine on the fill....per the table....you could have up to 15 #10's in there....though I wouldn't go that many unless it was a short straight run. It's bad enough pulling that many wires through steel conduit....

Your wise going with 1"....while your at it...toss in a spare wire or pull string....you never know....
I plan to come out of the back wall of the garage which is vinyl siding over sheathing. I also want to pull wiring to a shed exiting from this same wall cavity. Does anyone have recommendations on the best type of junction box to use that will meet code and allow me to have multiple PVC conduit runs exiting it and going underground from a single junction box (as well as the best way for attaching it)? I could do multiple LBs side by side, but I thought a single box might be a somewhat cleaner look. It might also decide to run another conduit run from this same exit point at a later time for landscape lighting etc. I doubt that it would be legal to do an underground split via a tee or y to branch off to both the hot tub and the shed, especially since the conduit needs to be constructed ahead of time (it would be difficult to navigate a fish tape through to the correct side of the tee/y). I'm hoping it would still be legal to have multiple runs enter the junction box from the wall cavity and exit via their own dedicated conduit runs. I have seen boxes that appear to be made to accommodate this configuration.

If I do go with PVC LBs, what would be the best way to secure the LB where it comes through the vinyl and sheathing into the wall cavity on the inside? If the nipple of the LB isn't long enough to make it through the sheathing I could glue a short section onto it, but I'm wondering what would be the best thing to use on the end of the nipple to prevent it from being pulled back through the sheathing.

Best Regards,

Ted
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Old 03-29-2012, 06:58 PM   #11
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Total Degrees of Bend in Underground PVC Conduit


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Does your area require a disconnect within sight of the hot tub?
I'm being entirely serious...are there areas that amend the NEC as to not require it?
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Old 03-29-2012, 07:12 PM   #12
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Total Degrees of Bend in Underground PVC Conduit


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Originally Posted by tedallen View Post
Does anyone have recommendations on the best type of junction box to use that will meet code and allow me to have multiple PVC conduit runs exiting it and going underground from a single junction box (as well as the best way for attaching it)?
You can buy many different size PVC pull boxes and just drill the holes you need. Another option is one large feed to a panel instead of a junction box then go to all your other areas from there. Sometimes not much more to have a panel there than running all the separate feeds and installing a junction box.
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Old 03-29-2012, 09:02 PM   #13
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Does your area require a disconnect within sight of the hot tub?
Yes. I have a disconnect (came with the hot tub) that contains two GFCI breakers, 30 amp and 20 amp. This will be a subpanel to the main breaker panel which will be fitted with a 50 amp breaker with two hots, a neutral, and a ground running from it to the hot tub disconnect panel (neutral and ground on separate bars in the disconnect panel). It must be no closer than 5 feet and no more than 50 feet from the hot tub.

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