Conduit question?


Old 08-12-07, 07:03 AM
Unclediezel's Avatar
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Conduit question?

Im almost ready for my "SUPPLY RUN" at the big box store. Unfortunately those guys cant give me an answer on a few determining factors. I'd rather put it past you guys anyway.

#1 Code allows only 4 90 degree turns in conduit? Do pull boxes eliminate this rule? I cant possibly route to where I need to go with only 4 turns. If so, How many pull boxes can I use? Do "L" boxes count as "Pull Boxes"?

#2 I will be using SCH 80 pvc, in an "Unfinished" Crawl space( with no chance of it ever being finished) Because of damp conditions. I have approximately 15 feet of space where it will be in the house, concealed in drywall. Provided all junctions are accesible, can I use the pvc indoors, or do I need to transition to Metal for the indoor areas.

#3 Just to run the "OVERALL" past you guys--
70a DP in the main panel -#4 thwn in 1.25 pvc sch80 to a subpanel 60 feet away (As the conduit runs). 70 amp backfed breaker in the sub (8-16 Sq D QO 100a) #8 bare copper ground. as measured 42 amps running with 22 amps as the Largest surge , No continuous loads.

Am I missing anything? Thanx

Last edited by Unclediezel; 08-12-07 at 07:07 AM. Reason: misspell
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Old 08-12-07, 07:15 AM
nap's Avatar
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didn't do the load calcs... the mind is still fuzzy this morning.

360 deg between pull points is the rule so putting in a junction box allows another 360 after it.

PVC as you intend..absolutely fine, but why sched 80 rather than sched 40? additionally, you could use EMT or steel rigid in this application as well if desired. PVC is less expensive so preferable because of that.

IF youhave extreme temp differences between the crawl space and the interior, you need to users duct seal or some other method to seal the pipe (interior portion) around the wires to prevent exchange of those temp differences.

I believe the rest is ok. the ground can be insulated (I always use insulated. that is what I always have on my truck 'cuz I use the #8 for other things as well as the grrounds)

your wire type needs to be THWN or other similarly rated "wet" application acceptable insulation.

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