Galv RIgid Elbows in PVC run

[Fordean]

I proposing a bid. On 4in conduits. Some up to 100 feet and communication 300 feet. I am considering, to use a GRC elbows, when is it necessary to use GRC ELbows


Example. Trans Pads.

Utility pole.

300 feet runs with 3 - 90's

I actually seen a Conduit PVC Elbow get cut in some runs.

Any input.
Thanks

 

[John120/240]

I actually seen a Conduit PVC Elbow get cut in some runs.

Any input.
Thanks

Correct. as long as your rigid elbows are at least 18" below grade no additional bonding is required.

 

[kingpb]

The use of GRC elbows is due to the pulling method. The PVC can be damaged during pulling by the rope, which can cause many sorts of issues.

One instance where you do not want to use them would be if each phase was installed in a separate conduit. Luckily, not many instances where this occurs.

 

[raider1]

You may also want to look into using RTRC (fiberglass) elbows, they hold up better then PVC and don't require bond like GRC does.

They are also cheaper then GRC.

Chris

 

[Fordean]

Phasing in conduit

Phasing in conduit

The use of GRC elbows is due to the pulling method. The PVC can be damaged during pulling by the rope, which can cause many sorts of issues.

One instance where you do not want to use them would be if each phase was installed in a separate conduit. Luckily, not many instances where this occurs.

I just read that having all A phase, B Phase, C PHase. Can change Variables in AIC and so forth. Glad I read this. Because I was considering putting all A phases in one conduit.

But engineer spec 5 conduit of 4- 500 MCM. So I figured I would have 5- 5oomcm in only four conduits. I still would like to put all A Phase in one conduit . Due to the Buss Termination a lot neater with no crossovers.

Im afraid. WIth all these conductors crossovers may not go well.

 

[kingpb]

My recommendation would be to do what the engineer designed. If you don't the Owner could come back and make you do it the way it was specified/designed.

Also, the 5 conductors per conduit now have to be de-rated because of number of current carrying conductors, which could change the size of conductor.

 

[tom baker]

The use of GRC elbows is due to the pulling method. The PVC can be damaged during pulling by the rope, which can cause many sorts of issues.
QUOTE]

Try pulling with Neptco mule tape. Its a woven pulling line that won't burn thru the 90s'.
http://www.neptco.com/website/neptc...6d7c010ecaaeb78e852575b00055e1c1?OpenDocument
Its marked with the footage, pull it in, get your cuts and pull the conductors.
Advantages:
Pre-lubrication reduces friction levels and eliminates duct cutting.
Lower elongation reduces pulling time, enhances worker safety, and prevents crushed capstans
Lightweight, easily blown through conduit or innerduct
Accurate sequential footage or meter markings enable monitoring of cable location during a pull, eliminate the need for measuring tapes, and help determine the quantity remaining on a partial roll
Variety of constructions available
Packaged in splice-free lengths up to 100,000 ft. (30 km) for faster, easier cable placement
Available in a variety of strengths up to 6,000 lbs (2727 kg)
Easily spliced using conventional methods and/or our own MULEKNOT? (Click here for splicing instructions.)

Once you use Mule Tape you will take all the poly line and use it for crab traps

 

[ptonsparky]

Steel cable doesn't seem to cut the PVC either. At least we haven't had a problem yet. Generally for long pulls we do use fiberglass on the pulling end at least. Our tuggers are a bit different. The Nissan died so any of three other makes take its place.

 

[GoldDigger]

SWAG. The heat capacity and heat conduction of the steel wire keeps the PVC from reaching the melting temperature from friction. during the pull.

Tapatalk!

 

[Canton]

The use of GRC elbows is due to the pulling method. The PVC can be damaged during pulling by the rope, which can cause many sorts of issues.
QUOTE]

Try pulling with Neptco mule tape. Its a woven pulling line that won't burn thru the 90s'.
http://www.neptco.com/website/neptc...6d7c010ecaaeb78e852575b00055e1c1?OpenDocument
Its marked with the footage, pull it in, get your cuts and pull the conductors.
Advantages:
Pre-lubrication reduces friction levels and eliminates duct cutting.
Lower elongation reduces pulling time, enhances worker safety, and prevents crushed capstans
Lightweight, easily blown through conduit or innerduct
Accurate sequential footage or meter markings enable monitoring of cable location during a pull, eliminate the need for measuring tapes, and help determine the quantity remaining on a partial roll
Variety of constructions available
Packaged in splice-free lengths up to 100,000 ft. (30 km) for faster, easier cable placement
Available in a variety of strengths up to 6,000 lbs (2727 kg)
Easily spliced using conventional methods and/or our own MULEKNOT? (Click here for splicing instructions.)

Once you use Mule Tape you will take all the poly line and use it for crab traps

When you use that mule tape with larger conductors, what do you use to pull it with? Can you wrap the mule tape around a tugger?

 

[ptonsparky]

SWAG. The heat capacity and heat conduction of the steel wire keeps the PVC from reaching the melting temperature from friction. during the pull.

Tapatalk!

That, roughly, is how I have explained it to my help.

 

[augie47]

WOW! The experience of Forum members sure shows in this thread.
FWIW one of our local utilities is changing over to the RTRC elbows after a study, and the local POCOs won't allow all phases in one conduit albeit PVC due to a problem they say occurs at their pads..

 

[kwired]

WOW! The experience of Forum members sure shows in this thread.
FWIW one of our local utilities is changing over to the RTRC elbows after a study, and the local POCOs won't allow all phases in one conduit albeit PVC due to a problem they say occurs at their pads..

What is their typical pad design like? Around here they generally are setting a fiberglass base and the padmount sits on top of it, with a hole in the bottom (well I guess it is the top) of base for conductors to pass thru into the padmount. Conduits usually end well below the top of the base and all that passes through the base into the padmount is the conductors themselves. Can't see much of a reason for anything to be a problem no matter if it is one phase per raceway or not.

 

[mjmike]

In an underground PVC duct bank where GRS is used at the elbow, where does it state it requires a ground bond? Then, where does it state the bond is not required if the GRS is deeper than 18"?

 

[kwired]

In an underground PVC duct bank where GRS is used at the elbow, where does it state it requires a ground bond? Then, where does it state the bond is not required if the GRS is deeper than 18"?

250.80 and the exception cover both of your questions for service raceways, and 250.86 and exception 3 covers non service raceways.

The duct bank could complicate this one some, but I'd bet that if a metallic elbow is used the same 18" cover requirement is necessary if it is not going to be bonded.

 

[Fulthrotl]

Once you use Mule Tape you will take all the poly line and use it for crab traps

yeah. what he said.

it won't cut pvc.
you can get it up to 6,000 lb test. 2,500 lb. (3/4" wide)
is what i use for pulling longer feeders than my
pull rope.

pull rope usually comes in 300' and 600' chunks.
so, you put a mule tape into the pipe, tie on your
pull rope, and pull it thru with the tugger, starting
the pull with the mule tape. generic mule tape won't
feed well over the capstain, so i just let it wind over
itself and roll up into a ball. when the capstain is full,
i back it off a turn to loosen it, pull off all the mule
tape, and repeat until you get to the rope.

by the time you get to the hard end of the pull, you
are into your pull rope, and it's not an issue.

note: if you are still over 600' away, and have so much
load on the mule tape you break it, before you get to the
pull rope, you have more problems than an internet forum
can help with.

good luck.

 

[Fulthrotl]

When you use that mule tape with larger conductors, what do you use to pull it with? Can you wrap the mule tape around a tugger?

yeah. take a couple turns around the capstan, and let it walk on itself.
then back off when the capstan is full.

if you try to wrap it like a normal pull rope,
about one time in ten it'll work, the rest of the
time, it'll shred the mule tape. not a good thing
to deal with at the start of an 800' pull. :rant:

a note... there is the "real deal" muletape, which
WILL lay nicely on the capstan, and the knockoff
mule tape, which won't.

you get what you pay for. unfortunately, my
wholesale house sells the cheap stuff, 'cause the
real deal is quite a bit more money, and the sparkies
won't pay for the premium product.

 

[mjmike]

250.80 and the exception cover both of your questions for service raceways, and 250.86 and exception 3 covers non service raceways.

The duct bank could complicate this one some, but I'd bet that if a metallic elbow is used the same 18" cover requirement is necessary if it is not going to be bonded.

Thanks for the info. That clears it up. It was also interesting that concrete could lessen the 18" depth for only non-service ducts.