Mixing wire types ok?


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Old 03-16-15, 09:23 AM
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Mixing wire types ok?

I am running a new line underground in 1" PVC using XHHW #10 green, #6 White and two #6 black.

My supplier says they are out of XHHW white. They said they can send me XLP- USE-2 #6 white in it's place.

Is it ok to mix XLP- USE-2 and XHHW in the same run like this?
 
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Old 03-16-15, 10:14 AM
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I see no issues mixing the two types of wiring in a common conduit.
 
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Old 03-16-15, 10:54 AM
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You can also use gray instead of white.
 
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Old 03-16-15, 11:27 AM
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In this case it depends a little bit. The XHHW and USE-2 are probably exactly the same wire due to economy of scale manufacturing; however from a legal marking point of view XHHW is allowed inside structures and USE-2 is not unless it also carries an RHH or RHW-2 marking. This relates to the fire/smoke rating of the insulation. Now if this run in conduit is entirely outdoors, then it doesn't matter either way. If it enters a structure, then you should only sub in the USE-2 if it also carries the RHH or RHW-2 mark (most does nowadays).
 
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Old 03-17-15, 09:37 AM
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Excellent info, thank you! This project does enter a building from outside, so I will need to verify the RHH or RHW-2 rating.

I will also consider just going with Gray as ray mentioned. The supplier suggested just taping a black wire with white tape, and I was not fond of that approach for lots of reasons.
 
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Old 03-17-15, 09:47 AM
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The supplier suggested just taping a black wire with white tape - See more at: http://www.doityourself.com/forum/el....fxXBRJP3.dpuf
But not code compliant for #6 or smaller.
 
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Old 03-17-15, 11:39 AM
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I am running a new line underground in 1" PVC using XHHW #10 green, #6 White and two #6 black.

My supplier says they are out of XHHW white. They said they can send me XLP- USE-2 #6 white in it's place.

Is it ok to mix XLP- USE-2 and XHHW in the same run like this?
Are the #10 and #6 XHHW wires copper or aluminum? If copper I think I would rather use THWN rather than USE-2.
 
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Old 03-18-15, 09:25 AM
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@CasualJoe, it's Copper. I shoulda mentioned.

My understanding is that XHHW is better than THHN with W rating (or THWN). Despite the wet rating of the T series, the XHHW is truly suited for outdoor runs, the insulation material being the big difference. Cost difference is minor. A significant factor is the need to pull through PVC conduit, so I do want workable cable for that.

USE-2 I know little about. Supposedly its a "higher quality" XHHW, but I dunno.

My setup:
I have 100 feet of 4-4-4-8 going from outdoor side of my house to a shed (sub-lug inside the shed) in 1 1/4" PVC conduit, and then I have 100 feet of 6-6-6-10 in 1" PVC going from the shed to a greenhouse which uses an external box (treat inside the GH as an outdoor situation - wet conditions all around). I'm still deciding on breakers, but am thinking 60A at the house feeding the shed, and then 30A from shed feeding the Greenhouse. I'm told by pros my wire selection is overkill for all this, but future proofing is fine by me.
 
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Old 03-18-15, 03:57 PM
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If the supplier can give you the white in XLP-USE-2, go with it. USE-2 is rated for direct burial so the insulation may be thinker than XHHW insulation. It is extremely hard to find copper XHHW anywhere anymore and especially in the smaller sizes. Most supply houses only stock larger sizes XHHW in aluminum. I have seen engineer's specifications sometimes written where all conductors used in conduit below grade, inside and outside, on a project be Type XHHW.
 
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Old 03-20-15, 06:50 AM
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The X in XHHW and the XLP in the USE-2 both stand for cross-linked polyethylene. They are the same material which perhaps a slight difference in overall thickness or additives for flame and UV resistance, but they will be nearly identical. Both are extremely durable and will be fine installed in conduit. XLP is tough to strip even with a very sharp knife. It is very resistant to accidental damage.
 
 

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