Mechanical Chase

[Alwayslearningelec]

I am bidding a job that has a mechanical chase. THere is a detail for it that show the electrical conduits, plumbing pipes etc. Is there anything special I should know about this that someone has experienced? My spec only calls for rigid pipe in the following locations so I assume I don't need rigid there but I was wondering about anything else. It is new constructions, I have never come across a mechanical chase w/electrical conduits. Thanks.

Outdoor exposed
Mechanical rooms
Loading dock

 

[jeremysterling]

I don't know if this helps, but I worked on a three story retail shell that had two large (~ 15' X 10') mechanical chases. The GC told me I could run conduit in them. I did not put conduit in the chase. There was no way for me to easily support conduits in these chases. And, there was no way for me to easily work in the chase.

After they were dried in, they were pretty inaccessible. A 29' scissor may have reached the first and second floors. To me, they were useless for electrical conduit, even communication conduits. I cored near columns to move pipe between floors.

 

[Alwayslearningelec]

This chase actually runs horizontally about 80'. THanks thought Jeremy.

 

[charlie b]

I have a new construction project being built right now, and I specified essentially the same requirements. I have not had a chance to see how the EC has been running conduits in the two large chases, and specifically how they have been supporting them. But I have not heard any questions or issues with installing conduits in a chase. Next time I am on site, I will try and get a look. But this thread will have faded into the sunset by then, I fear. So I guess I will not be of much help to you.

 

[infinity]

We run conduit in mechanical chases before. Not much to know except that you might not be able to install pull boxes in them. This can be a problem especially on vertical runs where conductor support is needed.

 

[growler]

This chase actually runs horizontally about 80'. THanks thought Jeremy.

Well I would think that having a mechanical chase is a good thing but I would check the other drawings to see how large the chase is and what else is going in there. You have to work with other trades on a job like this and electrical normally get last priority on space.

How many runs of conduit need to be in this chase ( include spares) and will one rack cover everything ( is there a way to build and support this rack). If they can build a rack with an 80 ft straight run then it would be a piece of cake. Conduit runs fast when you can run straight and level.

 

[Alwayslearningelec]

Great guys, thanks for your help. Some very good insight.

 

[sameguy]

Just look for the other trades, they will get first "dibs" on space; expansion joints, fire stop, etc.

 

[cadpoint]

Bare any other trades/code issues and if you coordinate with the other trades you can do it.

If it's OK, you have to get in there when the framer encloses the inside of the chase wall (one side).

I used a kendurf off the side of the interior wall to hold the run at required height(s).
I also drilled or shoot to the slab at each floor level. The conduit ends; was for me an ?L? at the bottom of the second
floor and a 90 out to a pull box right outside the shaft at roof.

Your situation might be different because they want rigid conduit, it might be a true fire rating issue and each
floor will be sealed at the other contractor?s expense, that?s why you?ll need to know exactly what they will do.

Rigid seems extreme but it could we be required by the nature of the structure. I got away with compression
fitting on EMT, the shaft was never closed at first floor but was double rock thick green board and sprinkled at the top.

Maybe an RFI is in order, maybe they just like the rigid thought when it?s not really required, it all depends.
For all the good that will do, your mileage may vary!

Yes truly an extra conduit after accounting for all services, and if you?re running a conduit for the fire guy.
It will probably be used just the same?

 

[Alwayslearningelec]

Bare any other trades/code issues and if you coordinate with the other trades you can do it.

If it's OK, you have to get in there when the framer encloses the inside of the chase wall (one side).

I used a kendurf off the side of the interior wall to hold the run at required height(s).
I also drilled or shoot to the slab at each floor level. The conduit ends; was for me an ?L? at the bottom of the second
floor and a 90 out to a pull box right outside the shaft at roof.

Your situation might be different because they want rigid conduit, it might be a true fire rating issue and each
floor will be sealed at the other contractor?s expense, that?s why you?ll need to know exactly what they will do.

Rigid seems extreme but it could we be required by the nature of the structure. I got away with compression
fitting on EMT, the shaft was never closed at first floor but was double rock thick green board and sprinkled at the top.

Maybe an RFI is in order, maybe they just like the rigid thought when it?s not really required, it all depends.
For all the good that will do, your mileage may vary!

Yes truly an extra conduit after accounting for all services, and if you?re running a conduit for the fire guy.
It will probably be used just the same?

They want rigid in mechanical ROOMS. Do you think that means the mechanical chase as well? I thought not.....although maybe

 

[iwire]

They want rigid in mechanical ROOMS. Do you think that means the mechanical chase as well? I thought not.....although maybe

If the specs say RMC in mechanical rooms I would not assume I need RMC in a chase. A chase is not generally a 'room' and is not subject to the damage that a room is subject to.

 

[Alwayslearningelec]

If the specs say RMC in mechanical rooms I would not assume I need RMC in a chase. A chase is not generally a 'room' and is not subject to the damage that a room is subject to.

Thanks, that what I thought.