4" rigid 90

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PCN

PCN

Senior Member
Location
New England
What radius 4" rigid 90 would you recommend for a 175' pull with (4) 500's and a # 3 ground? There will be a total of (3) 90's in the entire run.

Would a standard radius 90 make the pull a nightmare?

Thanks,
 
P

Power Tech

Senior Member
Location
Lebec, California
PCN said:
Yes we have room. This is from a padmount utility xfmr to a small mdp.

I'm trying to figure out what size bond out to ask for in the foundation which is a 4' frost wall.
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The utility company should spec out everything. You are going to a meter? For 4" they spec out 48", sch 80 sweeps. If the run is long or they are worried about burn through they will spec out fiberglass sweeps. If it is coming off a POCO xfmr, they will pull. You need to contact a service planner with the POCO.
 
walkerj

walkerj

Senior Member
Location
Baton Rouge
Trying to bend one piece of 500 to the shape of a short radius ninety is a workout enough.

If you have the room, 48" is the best way short of bending your own segmented bend.
 
masterinbama

masterinbama

Senior Member
Location
Huntsville Alabama
On a mostly horizontal pull my wire pull calculator changes very little when going from 16" radius 90's to 30" radius 90's. With ridgid conduit I would not even try 48" 90's due to the difficulty in threading them on your run (even in the wide open it would be a pain).
 
S

SEO

Senior Member
Location
Michigan
PCN are you going to buy factory 90's or bend your own? If this is for the POCO they will probably have their own specs as far as to radius.
 
masterinbama

masterinbama

Senior Member
Location
Huntsville Alabama
Power Tech said:
The utility company should spec out everything. You are going to a meter? For 4" they spec out 48", sch 80 sweeps. If the run is long or they are worried about burn through they will spec out fiberglass sweeps. If it is coming off a POCO xfmr, they will pull. You need to contact a service planner with the POCO.
Click to expand...

SEO said:
PCN are you going to buy factory 90's or bend your own? If this is for the POCO they will probably have their own specs as far as to radius.
Click to expand...

Where do you guys live? Our POCO here will only pull primary cable to their pad mount. We still run the conduit for the primary ,secondary to meter or ct can and from there to distribution. We also provide the wire and labor from the pad mount in. They will terminate at their transformer though.
 
PCN

PCN

Senior Member
Location
New England
SEO said:
PCN are you going to buy factory 90's or bend your own? If this is for the POCO they will probably have their own specs as far as to radius.
Click to expand...

This is a project that we are doing the design on (I work for an in house design team for a retail company these days). So I'm not sure. I'm mostly trying to figure out what size bond out to have in the foundation.

As you know a 48" sweep takes up alot more real estate than a standard 90.
 
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PCN

PCN

Senior Member
Location
New England
masterinbama said:
Where do you guys live? Our POCO here will only pull primary cable to their pad mount. We still run the conduit for the primary ,secondary to meter or ct can and from there to distribution. We also provide the wire and labor from the pad mount in. They will terminate at their transformer though.
Click to expand...

That how it usually works up here as well, utility just pulls the primaries. I'm mostly familiar with Maine's POCO though and this job is in New York.
 
ohmhead

ohmhead

Senior Member
Location
ORLANDO FLA
PCN said:
What radius 4" rigid 90 would you recommend for a 175' pull with (4) 500's and a # 3 ground? There will be a total of (3) 90's in the entire run.

Would a standard radius 90 make the pull a nightmare?

Thanks,[/QUOTE


Well yes its fine three 90 s in a run of 175 is a piece of cake go for it .

We kinda do it everyday most underground 90s used are 24 inch radi now when your pulling at say 450 feet it becomes a problem !

But we use a tugger it would be hard if your pulling by hand .
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e57

e57

Senior Member
Location
San Francisco, CA
Here - we do the conduit for the POCO - but to THEIR SPEC'S - a mandrel doesn't go through - they walk away with their wire. And won't let you pull your own...

Best to check with them....

If not a poco install - at least 24 vertical, if not 36 vertical and horizontal with steel on the pulling end(s) - lot o' lube. A lot of things can happen underground over 175'.... Nothing like digging it back up.
 
P

Power Tech

Senior Member
Location
Lebec, California
Rigid steel[/QUOTE]

Ouch. Trade secrete (ha ha): When you go to put the rigid steel together, backspin the coupling on the next stick half way. Then you can spin the conduit tight.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The radius of the bend does not enter into the pulling force calculation. It is however an issue in pulls because of the "side wall pressure". That is the crushing force that is applied to the conductor insulation as it goes around the bend. The larger the radius the lower the sidewall pressure. When you do pulling calculations, the side wall pressure is most often the limiting factor. It is a rare run where the pulling tension is the limiting factor. There is a pulling calculator here, but it is some what difficult to use.
 
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