Can neutral service wire be insulated?

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Two questions.
Can the neutral wire coming from the meter pan to the main panel be insulated? I just bought enough 2/0 THHN to run the two mains and the neutral.
What is the minimum size sch 40 pvc conduit required for 3 2/0 THHN wires? If it matters the conduit run will be less than 5'.
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Of course. Mark it with white tape or paint at the ends, so you know which one is the neutral.

For 3 wires, maximum conductor fill is 40% of the conduit cross-section. Per 2008 NEC, Chapter 9, Table 5, the cross-sectional area of one 2/0 THHN is 0.2223 sq in, so three of them is 0.6669 sq in. Your conduit needs to be at least 2.5 times that area, or >= 1.667 sq in. Per Chapter 9, Table 4, the smallest Sch.40 PVC conduit that is large enough is 1-1/2".
If you have even one bend to go around, you will find the conductors *much* easier to pull if you use 2" conduit.

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On Jan 21, 11:09 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

Thanks Doug.
I was thinking about using 2" PVC but the LBs are huge. Not a problem outside but fitting a 2" LB inside between the joists to make the turn down to my main panel is going to be really tight. To make it even more difficult several of the branch circuit wires run straight up above where the panel is going.
I'll probably go with the 1 1/2" only do give myself a little more room around the conduit. The run is pretty short: 2' from the meter pan- 90deg turn into house- almost an immediate 90 again to go down to the panel.
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Don't say I didn't warn you. :-)
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It'll be a bitch in 1 1/2. If it's a one time deal lay out your wire and put each piece of conduit on it one at a time. In other words put the conduit on the wire instead of pulling the wire through the conduit.
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Limp Arbor wrote:

A few months ago I got a "small" 2" LB at Lowes. It was right next to the normal giant ones. My brother the electrician was half joking half serious mumbling under his breath asking himself why he even showed me the small ones and let me choose. I can only imagine how difficult a 1.5" will be. And I also was wondering if in most applications the neutral would normally be a size smaller? If things are tight, can you strip the insulation off of the neutral to make things just a tiny bit easier?
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I'm convinced. I'll go with the giant 2" LB only because using a DWV sch40 long sweep painted grey might make the inspector frown.
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Limp Arbor wrote: ...

Again, look at access fittings; they're 90-degree w/ access for the pull to make it straight shot as well as take up less room in tight locations.
--
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This may work http://www.grainger.com/Grainger/items/4FYE8
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Limp Arbor wrote:

If you're short on room I'm talking about these --
<http://www.qcsupply.com/qcsupply/browse/productDetailWithPicker.jsp?productIda078&categoryId 735&fromPage=subcategory>
This was first one loaded; it's 1-1/4" but they're made 2" and larger. As well as this configuration there are others that change orientation of the short side to handle whichever direction the bend needs to go...
I was pretty sure I'd seen conventional pull-elbows at least 1-1/4" and surprised if they're not available even larger as well but perhaps not.
--
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wrote:

This may work http://www.grainger.com/Grainger/items/4FYE8
===================================== You can also use yellow pulling grease.
--
EA




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Limp Arbor wrote:

If the panel is on a basement wall you may have enough wall width to use a sweep (your Grainger item). It would be MUCH easier. Carefully plan. You may be able to shorten the sweep. If you cut one side back you may get to where the PVC is not round anymore.
Back-to-back LBs, with the back of one LB running into the back of the other LB, are a GIANT pain to get the wires into. Maybe a BFH and one of them alleged dynamite torpedos.
For one LB and your short dimensions you can put a 90 degree bend in a wire and push the wire in both ways at once. Do one wire, then the second, then the third.
LB ("conduit body") size is regulated by the NEC in 314.16 and 314.28. They are large because they need to be to get the wires into them. Restrictions kick in when wires are #4 or larger.
--
bud--

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Limp Arbor wrote: ...

Google "pull elbow"
--


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I doubt you will find them any bigger than 3/4". He is stuck with an LB
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snipped-for-privacy@aol.com wrote:

OK, "access fittings" for larger diameters.
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limp snipped-for-privacy@hotmail.com (Limp Arbor) writes:
| I was thinking about using 2" PVC but the LBs are huge. Not a problem | outside but fitting a 2" LB inside between the joists to make the turn | down to my main panel is going to be really tight.
Could you use 2" until the point where things get tight and then reduce? My service entrance conduit reduces near where it reaches the meter box.
                Dan Lanciani                 ddl@danlan.*com
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wrote:

Thanks Doug.
I was thinking about using 2" PVC but the LBs are huge. Not a problem outside but fitting a 2" LB inside between the joists to make the turn down to my main panel is going to be really tight. To make it even more difficult several of the branch circuit wires run straight up above where the panel is going.
I'll probably go with the 1 1/2" only do give myself a little more room around the conduit. The run is pretty short: 2' from the meter pan- 90deg turn into house- almost an immediate 90 again to go down to the panel.
All the more reason to use 2". Three 90 degree bends in 2/0 are going to be hell in 1 1/2"
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On Thu, 21 Jan 2010 07:02:39 -0800 (PST), Limp Arbor

You can use insulated THHN/THWN for the neutral, just be sure to mark it white with paint or tape. Three 2/0s will fit in 1 1/2 pipe but usually they use 2" sch 80 for services, probably because that is what they carry on the truck. The Sch 80 part is up to your AHJ
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*Is there any particular reason why you can't use service entrance cable for this?
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Couldn't you also use 2" Greenfield, or Sealtite for this. You might have a time finding that size sold by the foot, but you can check around. I have never had occasion to buy any. Larry
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