Conduit Run S.O.S.

[Krim]

I would like some suggestions please on the best fittings to use in order to make this run and pull as easy as possible. The scenario is as follows :

From an existing 18" X 18" junction/splice box , I need to transition over 3 feet and 90 up about 30" into the bottom of a 225 Amp Service Panel(Nema 3R) of which will have feed through lugs. Back out the bottom, 90 straight back to another 90 and run the distance of about 48 feet horizontally along the edge of a concrete slab(8" thick) 90 back up again for an 8 foot vertical , 90 yet again to another horizontal run of about 18 feet, down 90 about 2 feet and yes transition yet again to another horizontal run in air (supported with either 6" x 6" treated posts or galvanized pipe secured at the base onto a concrete pad with cradle supports beneath the conduit) for a 12 foot span through the building wall into an existing 200 Amp subpanel. The area where the conduit will be in the air between buildings is not accessible by equipment so there is no worry as to the height, just stability of the supports.
The wiring will be 4 -#300 Aluminum conductors pulled through 3 inch diameter schedule 80 PVC . The area will be wet at least 95% of the time and I was intending to use type "XXHW" for the moisture resistance characteristics due to condensation buildup within the conduit. It will be susceptible to both cold and hot water overspray conditions on a regular basis.
Any and all advise or recommendations would be greatly appreciated due to the fact that I need to turn in an estimate for materials by this weeks ending .
Thanking you all in advance ,
Carl

 

[Krim]

Come on guys please. It's been 5 hours and no bites, has the creek run dry ?

 

[mdshunk]

Come on guys please. It's been 5 hours and no bites, has the creek run dry ?

That was too much to read. An isometric drawing would yield you better responses.

 

[Dennis Alwon]

I would limit my bends to 270 degrees and use as many pull boxes as possible between these bends. I would avoid lb's unless you are sure they are suitable for wires that size.

 

[iwire]

That was too much to read.

I agree, too hard to follow.

 

[bighills]

Yeah sorry dude, I stopped reading after the word "transision". But I have A.D.D. ...

 

[mdshunk]

Back out the bottom, 90 straight back to another 90 and run the distance of about 48 feet horizontally along the edge of a concrete slab(8" thick) 90 back up again for an 8 foot vertical , 90 yet again to another horizontal run of about 18 feet, down 90 about 2 feet

Man, that's a lot of 90's in a row. I suppose you omitted the pull box that you'd use in your narrative?

If you're using PVC, don't forget about an expansion fitting on those long runs. 3" stuff will snap right out of the fittings during the expansion and contraction cycle.

 

[Krim]

That was too much to read. An isometric drawing would yield you better responses.

Sorry guys I'm not much of an artist nor do I have any CAD experience. What is an isometric drawing anyway, a rough sketch ?

 

[electricalperson]

if i read it correctly it sounded like a lot of 90's. i would try to limit the amount of 90s and use PLENTY of lube. is there a more direct way to get to the end without all the bends?

 

[electricalperson]

Man, that's a lot of 90's in a row. I suppose you omitted the pull box that you'd use in your narrative?

If you're using PVC, don't forget about an expansion fitting on those long runs. 3" stuff will snap right out of the fittings during the expansion and contraction cycle.

you beat me

 

[Krim]

Man, that's a lot of 90's in a row. I suppose you omitted the pull box that you'd use in your narrative?

If you're using PVC, don't forget about an expansion fitting on those long runs. 3" stuff will snap right out of the fittings during the expansion and contraction cycle.

Well, those 90's are right angle areas needed to follow the existing structure contours. I'm not certain what the best way would be to follow along the outside edge of the concrete slab, up one buildings end wall and across high enough to clear the top of a doorway, down about 2 feet and finally another horizontal run supported by posts over to and into the end wall of building #2 (of which is where an existing 200 amp(main CB) subpanel is located that was previously used and will be put back into service once more).
This is a job where a partial building demolition has been done and where the original service was removed in the demo. So I need to install new conduit and wiring from a stubbed up junction box to a new NEMA 3R enclosure and panelboard(225 A) and to what's left of the 2 adjoining buildings so that the 2 buildings will again have power provided along with having an outdoor panel of which will supply power to the tank heaters.
Does this make anything clearer or only clear as mud ?

 

[mdshunk]

Does this make anything clearer or only clear as mud ?

You looked at the work, so honestly, you're the only one who can really say what the best approach will be. Sounds like a cluster-thing to me. I don't suppose that sawcutting the floor and running that pipe in a more or less straight line from 'A' to 'B' is an option, is it?

Of course, you can always run open wiring on insulators.

 

[Krim]

.... is there a more direct way to get to the end without all the bends?

Yea if they would pay to dig up the underground service on the opposite side of the concrete pad. But I suggested that and their reply was that it would cost too much.

 

[JohnME]

I just went through something like this- only with 300 mcm cu. I used LB's, and LL's. Just remember, if your going to use these fittings, UP your pipe size. I had a 3" EMT run and went to 4" to accommodate the above fittings. Put the fittings in the best place for pulling/feeding.

 

[electricalperson]

Yea if they would pay to dig up the underground service on the opposite side of the concrete pad. But I suggested that and their reply was that it would cost too much.

what would cost more? you digging up the service or all the labor and material involved?

 

[Krim]

You looked at the work, so honestly, you're the only one who can really say what the best approach will be. Sounds like a cluster-thing to me. I don't suppose that sawcutting the floor and running that pipe in a more or less straight line from 'A' to 'B' is an option, is it?

Of course, you can always run open wiring on insulators.

This is most definitely one of those cluster-things. I like the idea of cutting a trench into the concrete slab but the trenched area will have over 5K gallons of water in a fiberglass comp.tank on top of it. What kinda reinforcement would that require to keep the conduit from collapsing beneath ?

 

[JohnME]

I cant imagine that a properly filled in trench (compacter) would pose any issues at all. You could always lay rigid pipe in the areas your worried about and transition to PVC after.

 

[mdshunk]

This is most definitely one of those cluster-things. I like the idea of cutting a trench into the concrete slab but the trenched area will have over 5K gallons of water in a fiberglass comp.tank on top of it. What kinda reinforcement would that require to keep the conduit from collapsing beneath ?

Probably none, unless that 5,000 gallon tank was about 4" wide and sitting right over the conduit.

It sounds like from one of your last responses that your customer has pretty much dictated what the path will be. Bid it and go with the flow...

 

[peter]

I get about 93' of run and SIX 90? bends.
Since this is PVC, I would caution against using the factory bell ends. Cut them off, cut off the bell part and use the rest as a coupling. But that's beside the point.
You could possibly get by with one 90? bend: From the top side of the 225 Amp panel, run your tube straight to the wall, place your 90? IN the wall and it hopefully will end right at the side of your last panel.
But wait! there's more. If you replace the 90? with a pair of say 15? bends you can create an offset again into the back of your panel.
Placing two 90?s immediately adjacent to one another [one connected directly to the other] in different planes will make it impossible for a standard flat fish tape to go through since its plane of bending is set by the first bend. But that's the least of your worries.
Why do you have to drop down 2' for the open air part. Can't you use some sort of supports or stantions to support it in the air 2' higher? Or at least replace the two 90?s with a 22 1/2? offset. If any of this is underground or could be, then a couple of sweeps and a straight run should suffice.
But note: I have no idea of your actual situation, obstacles and whatnot so I don't know why you have all those ups and downs.
~Peter

 

[electricalperson]

if you dig a trench under the slab then lay the conduit inside and cover with dirt you can put rebar into the sides of the slab using a hammerdrill and fill with concrete and it should be enough. thats how the contractor company done it when i cut a slab for conduit