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practical sizing of pvc #39843 07/05/04 08:49 AM
Joined: Apr 2001
Posts: 83
D
donles Offline OP
Member
I'm running a u/g feeder via pvc from a combination meter/main panel on a customer owned pole approx. 160 ft. to a dwelling and will enter through the foundation wall.
200A service so it will be 3 2/0 cu conductors and a #6 EGC. The run has one 90 degree bend.
My question concerns sizing the pvc conduit.
I thought I'd use a sched.80 sweep 90 and sched 40 the remainder of the run. I was told that sched. 80 holds up to pull rope better. Tables 9 & 10 tell me that 2" pvc can contain up to 5 2/0 THWN for sched 80 and 6 2/0 THWN for Sched 40. Should I consider running larger PVC? I managed to borrow a tugger but this aspect of the job worries me the most.
Don

Work Gear for Electricians and the Trades
Re: practical sizing of pvc #39844 07/05/04 09:36 AM
Joined: May 2004
Posts: 81
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velect Offline
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If the 2/0 is thhn you will have no problem.

However I think you need to run #4 not #6

Re: practical sizing of pvc #39845 07/05/04 09:46 AM
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Roger Offline
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Don, 2" will be fine and if the 90 is at the pulling end forget the schd 80 and go with an IMC or GRC 90.

If the 90 is close to the feeding end there is not an issue, and schd 40 would be fine.

A pull rope will cut into schd 80 as easy as it will cut into schd 40

As long as all of the 90 is covered by 18" of fill there is no extra bonding needed.

Roger

Re: practical sizing of pvc #39846 07/05/04 09:54 AM
Joined: Feb 2003
Posts: 687
A
Active 1 Offline
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Don't jump on me if I'm wrong. Would you not need 3/o copper for 200A or 4/o Al. 2/o copper is good for 195 amps. I don't know what kind of load you have on this but voltage drop might another reason to use 3/0.

If the service is on the pole then I would say the #6 EG would meet code. Or you could eliminate the EG and bond the 200a panel if conditions are met.

Tom

Re: practical sizing of pvc #39847 07/05/04 10:11 AM
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Roger Offline
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Tom, for a 3 wire single phase service to a dwelling, table 310.15(B)(6) can be used.

Roger

Re: practical sizing of pvc #39848 07/05/04 01:46 PM
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donles Offline OP
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velect wrote
>If the 2/0 is thhn you will have no problem.

>However I think you need to run #4 not #6

I got #6 from table 250.122.
Am I wrong?

Don

Re: practical sizing of pvc #39849 07/05/04 02:01 PM
Joined: Jan 2003
Posts: 4,391
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iwire Offline
Moderator
6 AWG cu will meet code for a 200 amp feeder.

I can not recommend strongly enough to listen to Roger's advice about when to use a steel sweep.

If you think there is any chance you will use a tugger on this pull forget about plastic sweeps near the tugger end.

Once the rope cuts a nice thin slot through the inside radius you can for get about the wire getting through undamaged.

Pick up a steel sweep and two female adapters.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: practical sizing of pvc #39850 07/05/04 02:30 PM
Joined: Jan 2003
Posts: 4,391
I
iwire Offline
Moderator
Quote
If the 2/0 is thhn you will have no problem

THHN is not permitted in underground raceways.

You may have dual rated THHN/THWN which can be used underground but the ampacity will be based on THWN (75 C) along with the fact that the 90 C column is only useful for ampacity adjustments.

You will not find any terminals rated 90 C so you can not run the wire at the 90 C rating.

All of this does not matter as you can as Roger pointed out use table 310.15(B)(6) which allows 2/0 cu for a 200 amp service. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: practical sizing of pvc #39851 07/05/04 03:02 PM
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Posts: 83
D
donles Offline OP
Member
re: steel sweep
I appreciate the advice. I'll consult code concerning Roger's comment about the entire 90 being 18" below grade to avoid bonding issue.

I didn't know if I needed tugger. Got it just in case. More than likely I have to pull from the 90 end.

Don

Re: practical sizing of pvc #39852 07/05/04 03:18 PM
Joined: Jan 2003
Posts: 4,391
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iwire Offline
Moderator
Don you can trust Roger. [Linked Image]

Here is the code

Quote
250.86 Exception No. 3: A metal elbow shall not be required to be grounded where it is installed in a nonmetallic raceway and is isolated from possible contact by a minimum cover of 450 mm (18 in.) to any part of the elbow or is encased in not less than 50 mm (2 in.) of concrete.

I must do this quite often while running underground conduits.

If it is the sweep breaking the surface I simply continue with EMT or IMC to the enclosure to get the sweep bonded.

If it was me I would not plan on a tugger for this pull. I would plan on plenty of wire lube, a good rope and 3 people minimum by hand.

Two if pulling it with something else, we will use anything that drives (slower the better) to pull cables in.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
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