Definition of a Riser.

[dcasino]

I need a definition for the word riser.

Spec u/g section says to transition from underground to above slab with Rigid Steel.
Underground to be Rigid Non metallic Conduit

Underground bends to be rigid steel
Risers to be rigid steel

I have ran RNC between my 90 elbow and grade for final height adjustments and rigid steel above grade, owner says i can't transition from grc to pvc to grc
and is quoting " all risers to be rigid steel"

Risers are above grade, correct

 

[Rewire]

sounds like the owner gave you the definition.

 

[Smart $]

I don't believe there is any one ultimate definition. But I do offer the folllowing which coincides with my understanding...

Merriam-Webster Collegiate? Dictionary

ris?er
Pronunciation: 'rī-zər
Function: noun
Date: 15th century

1 : one that rises (as from sleep)
2 : the upright member between two stair treads
3 : a stage platform on which performers are placed for greater visibility
4 : a vertical pipe (as for water or gas) or a vertical portion of an electric wiring system
5 : one of the straps that connects a parachutist's harness with the shroud lines

? 2005 Merriam-Webster, Incorporated

As such, wherever you turn up an 90? elbow to emerge above grade, the entire vertical section must be GRC.

Welcome to the forum

 

[mxslick]

Whew, for a minute I though this was gonna end up being another hot-button thread. :grin: Larry saves the day again!!

dcasino, welcome to the forum!!

 

[cowboyjwc]

But it can only go up to be a riser, if it goes down then it's a downer.:grin:

Sorry couldn't resist. Have a great 4th everyone.

 

[iwire]

How come a riser diagram lays flat? :grin:

 

[don_resqcapt19]

The other issue with the PVC between the top of the steel 90 and the exposed steel pipe would be the bonding of the steel 90 if any part of is is less than 18" below grade. 250.86

 

[ohmhead]

I need a definition for the word riser.

Spec u/g section says to transition from underground to above slab with Rigid Steel.
Underground to be Rigid Non metallic Conduit

Underground bends to be rigid steel
Risers to be rigid steel

I have ran RNC between my 90 elbow and grade for final height adjustments and rigid steel above grade, owner says i can't transition from grc to pvc to grc
and is quoting " all risers to be rigid steel"

Risers are above grade, correct

Well most specs we see the engineer plainly states when you pass thur a concrete slab you must pass thur with a GRC conduit stub if your specs say 90 elbow and stub meaning riser then you must do as specs say .

Its cheaper to do it his way in my book this way you dont have to change from pvc to rigid twice and it would be a better grounding of the raceway completely you can cut and thread and adjust the stub up at finish grade i dont see the problem most jobs we do use rigid for stub ups pvc underground rigid 90 rigid stub up then we change to Emt or rigid conduit and rise up from that point .

Specs are the bible unless you can VE them out by writing a RFI to engineer but pvc in the middle is not something normally done so i think the engineer will not accept .As to the change from rigid to pvc to rigid electrically i dont see what reason he might say except its not a good thing with high voltage but at 480 volts i dont see it being a problem .

But what do i know i just run conduit all day !

 

[mxslick]

How come a riser diagram lays flat? :grin:

How come we park on a driveway and drive on a parkway? :grin: