How large does a chase need to be for (8) 2-1/2"C

[kevinengineer99]

Hi all,
How large does a vertical chase need to be to run (8) 2-1/2" conduits between floors? Is there a general calculation for x number of y size conduits? How do we account for working space?
Thank you.

 

[Rock86]

I've tried to solve this before on projects by finding the outter diameter of the conduit, then using a conduit spacing chart, draw the most efficient chase size based on your conduit spacing.

 

[infinity]

What type of conduit and what is your spacing? You can probably go as little as 3/4" of an inch between each conduit. 2.5" metal conduits are about 3" in diameter.
(3"*8)+(3/4"*7)=29 ¼"

 

[Dennis Alwon]

Or double them up and make it 15" x 7" . You can always go larger.

 

[augie47]

Not sure how the conduits terminate but to avoid having to bend offsets keep your locknut & bushing dimensions in mind.
(Learned from my own error...punch holes based on conduit and then can't get fitting on easily)

 

[LarryFine]

Not sure how the conduits terminate but to avoid having to bend offsets keep your locknut & bushing dimensions in mind.
(Learned from my own error...punch holes based on conduit and then can't get fitting on easily)

Agreed! It's no fun when your locknuts mesh like gears.

 

[K8MHZ]

What type of conduit and what is your spacing? You can probably go as little as 3/4" of an inch between each conduit. 2.5" metal conduits are about 3" in diameter.
(3"*8)+(3/4"*7)=29 ¼"

Maybe trying to figure out the smallest chase isn't the right approach. The pipe installers will be happier with some room to work with vs. not.

 

[electrofelon]

Agreed! It's no fun when your locknuts mesh like gears.

They need to me left handed lock nuts and fittings then the intermeshing lock nuts can both be tightened.

 

[Terminator5047]

Installing buss duct would be cheaper

 

[infinity]

Maybe trying to figure out the smallest chase isn't the right approach. The pipe installers will be happier with some room to work with vs. not.

I agree, we use 1.5" spacing with 4" conduits. For 2½" EMT 3/4" will still work.

 

[Terminator5047]

Buss duct

 

[Terminator5047]

Also how tall are the floors? If you have 20ft floors your chase needs to be large enough for a scaffold to be built in it and work the pipe

 

[infinity]

Installing buss duct would be cheaper

How do you know that not knowing what these conduits are for?

 

[Terminator5047]

How do you know that not knowing what these conduits are for?

You’re right if the conduits are for data they would be a waste of money if it’s for power it’s cheaper. You would be surprised how cheep buss duct is and how much current it can carry for the cost

 

[kevinengineer99]

You’re right if the conduits are for data they would be a waste of money if it’s for power it’s cheaper. You would be surprised how cheep buss duct is and how much current it can carry for the cost

At what amperage does bus duct make sense? If I have 225A bus duct feeding panels on 5 floors, is it cost effective? From my call w/ a rep, currently there's a lead time of 6 months, plus higher metal costs, plus it requires on-site measurements to custom the bus duct, etc.
Thanks.

 

[kevinengineer99]

I agree, we use 1.5" spacing with 4" conduits. For 2½" EMT 3/4" will still work.

infinity,
Thanks for the answer. Is there a chart somewhere to look this up?

 

[kevinengineer99]

Also how tall are the floors? If you have 20ft floors your chase needs to be large enough for a scaffold to be built in it and work the pipe

It'll go up 4 floors so at least 40 ft.

 

[Terminator5047]

It'll go up 4 floors so at least 40 ft.

Right but are they 10ft floors 15ft floors 20ft floors you have to be able to support the conduits so u may need more working room if the floors are larger then 10ft

 

[infinity]

infinity,
Thanks for the answer. Is there a chart somewhere to look this up?

Not that I know of. 1.5" spacing is all that you would need if you wanted to go with the larger size. If room is tight you could shrink the spaces down but if you use 1.5" you won't have any issues with connectors or locknuts/bushings, etc.

 

[BeeBrave]

I've tried to solve this before on projects by finding the outter diameter of the conduit, then using a conduit spacing chart, draw the most efficient chase size based on your conduit spacing.

Rock86,
Where do I find such a chart? Thanks.