Mechanical Room Fire Wall Electrical Penetrations

Duncan8943

Member
Location
Lexington
I've got an architect that wants me to run my feeders and branch circuits under concrete. Tha main panel will be in a mechanical room and the person running the project said that he didn't think that I could penetrate the walls/ceiling because of the firewall. I have 4 main panels in 4 rooms with probably 120+ branch circuits that would all be under the concrete. It is obviously easier to go overhead with everything. It looks like the International Building Code allows conduit penetrations of walls with a fire rated sealant. I haven't seen anything addressing ceiling penetrations.

I was either going to drop into the panel with feeders from the ceiling and send the branch circuits out through the ceiling. This work is for an assisted living wing and everything will be in conduit or MC cable. I was planning on penetrating the ceiling with EMT on the feeder and from there going to plastic since I was out of the fire wall area. All opinions and options are welcomed.
 

eHunter

Senior Member
I've got an architect that wants me to run my feeders and branch circuits under concrete. Tha main panel will be in a mechanical room and the person running the project said that he didn't think that I could penetrate the walls/ceiling because of the firewall. I have 4 main panels in 4 rooms with probably 120+ branch circuits that would all be under the concrete. It is obviously easier to go overhead with everything. It looks like the International Building Code allows conduit penetrations of walls with a fire rated sealant. I haven't seen anything addressing ceiling penetrations.

I was either going to drop into the panel with feeders from the ceiling and send the branch circuits out through the ceiling. This work is for an assisted living wing and everything will be in conduit or MC cable. I was planning on peneetrating the ceiling with EMT on the feeder and from there going to plastic since I was out of the fire wall area. All opinions and options are welcomed.
What type of construction?
Single/Multi story?
Slab on grade?
Did architect/PM give any reason for no wall penetrations?
 

Duncan8943

Member
Location
Lexington
Little more information

Little more information

Single story. Slab on grade. Wood construction. I would consider this institutional, but it could possibly be argued residential. This is a new wing to the existing facility. The original building was done with all of branch circuits fed under the concrete. That is his only reference. When I started making comments about wall penetrations and sealing with a fire proof material, he said that he would have to talk to the state inspector. In this case, I don't think that anyone has ever pushed to do the electrical this way. I know the owner and don't see a reason for the incremental cost and labor.
 

kwired

Electron manager
Location
NE Nebraska
Ask him how they ever get power to anything above the first floor (or wherever service is located) in a multistory building:happyyes:
 

iwire

Moderator
Staff member
Location
Massachusetts
It is obviously easier to go overhead with everything.
Is it?

Given the choice we go under with as much as we can.

PVC is cheap, installs easily, you can run it 'as the crow flies' saving wire.

But yes of course you can penetrate fire walls if you use the correct methods ... which add costs and time.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Is it?

Given the choice we go under with as much as we can.

PVC is cheap, installs easily, you can run it 'as the crow flies' saving wire.

But yes of course you can penetrate fire walls if you use the correct methods ... which add costs and time.
I agree with Bob on all counts. If you do choose to go through the fire walls you may check into having a Fire Proofing contract take care of your penetrations if your area has strict enforcement.


Roger
 

kwired

Electron manager
Location
NE Nebraska
My experience is most of the time that slab is poured without the knowledge of electricians, and therefore running raceways below the slab is not going to be an option. They will contact plumbers to inform them they need drain lines in but will not contact electricians unless electrician has been on top of things and contacts the concrete guys in advance to work himself into their plans.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
My experience is most of the time that slab is poured without the knowledge of electricians, and therefore running raceways below the slab is not going to be an option. They will contact plumbers to inform them they need drain lines in but will not contact electricians unless electrician has been on top of things and contacts the concrete guys in advance to work himself into their plans.
That may be the case on small or residential work but, in large work the EC is given the same opportunity as the plumbing contractor to get their work in the slab. In the past few years another reason I try to get as much in the slab as possible is to keep our portion of BIM as small as possible.

Roger
 

kwired

Electron manager
Location
NE Nebraska
Do you think that applies to the OP?
I have no clue. Does that invalidate my experiences?

That may be the case on small or residential work but, in large work the EC is given the same opportunity as the plumbing contractor to get their work in the slab. In the past few years another reason I try to get as much in the slab as possible is to keep our portion of BIM as small as possible.

Roger
Define small. I am working on a shop building right now that is a pretty large shop, but compared to some industrial applications is a small project. I wanted to run some lines below the concrete in this project because it would cut down raceway and conductor lengths (otherwise it is 20 feet to ceiling and route in straight and square configurations as well as more time on the lift) but they already had the entire floor poured before anyone even told me they were starting:(
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I have no clue. Does that invalidate my experiences?

Define small. I am working on a shop building right now that is a pretty large shop, but compared to some industrial applications is a small project. I wanted to run some lines below the concrete in this project because it would cut down raceway and conductor lengths (otherwise it is 20 feet to ceiling and route in straight and square configurations as well as more time on the lift) but they already had the entire floor poured before anyone even told me they were starting:(
My definition of small is based more on procedure than actual size. Any project that doesn't have pre construction meetings, a construction progress schedule (with start and finish dates for tasks as well as milestones), or systematic planning is IMO small.


Roger
 

kwired

Electron manager
Location
NE Nebraska
My definition of small is based more on procedure than actual size. Any project that doesn't have pre construction meetings, a construction progress schedule (with start and finish dates for tasks as well as milestones), or systematic planning is IMO small.


Roger
That makes most of my projects "small". Some projects do have a hint of those mentioned items at times, but never all of those items on any consistent basis.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Fire rated partitions are penetrated everyday of the week with not only electrical installations but also sprinkler, plumbing, duct work, you name it. And a mechanical room would have more penetrations than any average room in a building. As long as the penetrations are properly fire-stopped there shouldn't be a problem.
 

Duncan8943

Member
Location
Lexington
Why would you want to go UG when you have a chase?

Why would you want to go UG when you have a chase?

This addition is over 200' long and 60' wide. Plumbers have already been there. There are 4 panels to be installed. 120+ branch circuits. I would have basically 120+ runs of 3/4" pvc under the slab--not including the feeders. Since this is a single story unit that will have a chase above the hallway, I would rather take advantage of this and use an approved method of penetrating the firewall. There is no risk in missing a wall when using this method. The amount of extra wire used by going overhead versus dropping to below the concrete is minimal compared to the additional work of installing the pvc. I would be eliminating the time to run the conduit and do the pulls to the first box. Using the 2' high chase in the hallway and pulling MC cable seems to make the job a lot simpler and faster.
 

iwire

Moderator
Staff member
Location
Massachusetts
Fire rated partitions are penetrated everyday of the week with not only electrical installations but also sprinkler, plumbing, duct work, you name it. And a mechanical room would have more penetrations than any average room in a building. As long as the penetrations are properly fire-stopped there shouldn't be a problem.
Yeah you do not normally see the duct work and sprinkler pipes run out of the mechanical room under ground.
 

iwire

Moderator
Staff member
Location
Massachusetts
This addition is over 200' long and 60' wide. Plumbers have already been there. There are 4 panels to be installed. 120+ branch circuits. I would have basically 120+ runs of 3/4" pvc under the slab--not including the feeders. Since this is a single story unit that will have a chase above the hallway, I would rather take advantage of this and use an approved method of penetrating the firewall. There is no risk in missing a wall when using this method. The amount of extra wire used by going overhead versus dropping to below the concrete is minimal compared to the additional work of installing the pvc. I would be eliminating the time to run the conduit and do the pulls to the first box. Using the 2' high chase in the hallway and pulling MC cable seems to make the job a lot simpler and faster.
You have lost me, above ground or below you still have to run 120 branches plus feeders

I know for a fact we could run all that underground cheaper than overhead. In this case the customer seems to prefer it underground so why not try it?

If you have the A prints hitting the walls is pretty easy.
 

Duncan8943

Member
Location
Lexington
A few more details

A few more details

The guy running the project just thinks that it needs to be UG based on the previous building. The actual owner prefers overhead and was the one that asked me if I could do it. I prefer it for the following reasons: (1) It eliminates the risk of missing a wall. (2) If I miss a wall, then there is a lot of extra work that I really don't want to deal with. (3) I can't be there when they pour concrete. (4) Four guys with two scaffolds can roll down the hall and make each run the very quickly after the concrete is pulled. (5) The cost savings/risk of UG versus overhead is not worth it.--I can't be there to babysit during the concrete and it could be as long as two weeks after the conduit goes in the ground before they pour concrete.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
The guy running the project just thinks that it needs to be UG based on the previous building. The actual owner prefers overhead and was the one that asked me if I could do it. I prefer it for the following reasons: (1) It eliminates the risk of missing a wall. (2) If I miss a wall, then there is a lot of extra work that I really don't want to deal with. (3) I can't be there when they pour concrete. (4) Four guys with two scaffolds can roll down the hall and make each run the very quickly after the concrete is pulled. (5) The cost savings/risk of UG versus overhead is not worth it.--I can't be there to babysit during the concrete and it could be as long as two weeks after the conduit goes in the ground before they pour concrete.
Although I don't agree with your argument, why not present it to the Architect?

Roger
 

jumper

Senior Member
The guy running the project just thinks that it needs to be UG based on the previous building. The actual owner prefers overhead and was the one that asked me if I could do it. I prefer it for the following reasons: (1) It eliminates the risk of missing a wall. (2) If I miss a wall, then there is a lot of extra work that I really don't want to deal with. (3) I can't be there when they pour concrete. (4) Four guys with two scaffolds can roll down the hall and make each run the very quickly after the concrete is pulled. (5) The cost savings/risk of UG versus overhead is not worth it.--I can't be there to babysit during the concrete and it could be as long as two weeks after the conduit goes in the ground before they pour concrete.
I have never went overhead as quick or as cost effective as I can do in UG, I am with Bob here.

While not as experienced as Bob, I can say that you will never finish a big box store/supermarket on time/budget going totally overhead.
 
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