|
1 members (Scott35),
528
guests, and
48
robots. |
|
Key:
Admin,
Global Mod,
Mod
|
|
|
|
Joined: Feb 2002
Posts: 36
OP
Member
|
Yeah, Resqcap...Schedule 40 PVC and I have no problem with 2"nipples or straight runs. Even the NEC table only shows a max. of two #4/0 RHW. One 90 is verticle, the other horizontal, both are buried leading into the control room....about 150-160 feet underground and an additional 75 feet up into the overhead tray and over into my distribution panels. We will see.....I'll keep you posted on how it goes.
|
|
|
|
|
Joined: Nov 2000
Posts: 2,148
Member
|
3rd degree,
I agree that the Table C10 says that only2 4/0 RHWs fit in a 2" schedule 40 PVC conduit, it also says that 3 4/0 THWs fit and 4 4/0 THWNs or XHHWs fit. With the proper equipment I don't see any problem other than the pull rope and or conductors cutting through the inside of the 90s. If this happens the conducotrs will be damaged.
Don(resqcapt19)
Don(resqcapt19)
|
|
|
|
|
Joined: Aug 2001
Posts: 599
Member
|
Don,
Mule tape is used by datacom people allot. I don't remember the exact material it's made of but it is smooth and flat with footage numbers stamped on it. I think its nylon. I have found it works well on small and medium size feeder pulls. It does not cut into PVC 90's. If I find a link or manufacturer I'll post back with it.
|
|
|
|
|
Joined: Dec 2000
Posts: 4,294
Member
|
Are you also including the #4 EGC in your calcs for conduit size? Doesn't it become 2-1/2"?
[This message has been edited by electure (edited 02-09-2002).]
|
|
|
|
|
Joined: Nov 2000
Posts: 2,148
Member
|
Electure,
I didn't include an EGC. I see that this is after the service disconnect so an EGC required and you are correct that when the #4 EGC is added a 2 1/2" conduit is requried.
Good catch!!
Don(resqcapt19)
Don(resqcapt19)
|
|
|
|
|
Joined: Feb 2002
Posts: 36
OP
Member
|
Like I said, tommorrow should prove interesting...........
|
|
|
|
|
|
Anonymous
Unregistered
|
I guess you would be referring to me and my fellow engineers. I woudl agree that a lot of engineers need to have field experience before entering into any job requiring design. I am very glad that I am still getting my field trainging while earning my degree. I have looked at designs from professors and fellow students that are almost impossible to do in the real world. The trouble always comes from the lack of field experience.
|
|
|
|
|
Joined: Feb 2002
Posts: 36
OP
Member
|
Electure, overheads are out of the question in a switchyard....EVERYTHING is buried in PVC (except for the high voltage transmission lines). I installed the disconnect about 20' below some comparatively small 38KV potential transformers....you get the picture.
|
|
|
|
|
Joined: Feb 2002
Posts: 36
OP
Member
|
Cool........we made our run today, a HARD pull, a tackle and a bucket of soap, but otherwise OK. Actually, we ended up pulling THW instead of RHW and only three 4/0's instead of four(2 hots & neutral). We will derive our ground somewhere else-son't ask, there are miles of grounded grid electrodes in a switchyard and the EGC will come into an overhead in an opposite direction than where I took our service-it gets complicated but the entire yard is fairly "flat" as a result). Really though, I don't think we could have negotiated that last PVC elbow if we had to pull four in that damn 2".
|
|
|
|
|
Joined: Aug 2001
Posts: 599
Member
|
We will derive our ground somewhere else-son't ask, there are miles of grounded grid electrodes in a switchyard and the EGC will come into an overhead in an opposite direction than where I took our service-it gets We did a small power plant last summer that I spent a few weekends at. The grounding (bonding) scheme was similar. Just tap into the ground grid anywhere. I did then and still do think it is a violation of 250.134(B). I don't understand why things suddenly change just because your we are inside a substation or power plant.
|
|
|
|
Posts: 99
Joined: August 2003
|
|
|
|
