Fire Walls

[pete m.]

This scenario is driven by building code and the subsequent question is compliance with article 225.

For a specific construction type a building is limited to a maximum square footage and height. If fire walls are utilized the appearance would be a contigous building that is actually multiple buildings under one roof.

For a large building, such as a school, the designer has chosen to separate the allowable square footage areas by fire walls. There is an MDP that feeds the entire school in one of the areas and then multiple feeders routed to and through the other areas to serve various panelboards and loads from the MDP.

I understand that I actually have "separate buildings" although the appearance is that of one building. Does anyone have any suggestions, short of a complete re-design of the electrical system, to comply with the NEC with particular respect to 225?

Thanks, Pete

 

[rcarroll]

I don't think you need to worry. Anytime you penetrate a fire wall, the annular space around the pipe, cable, or whatever will need to be properly filled w/ fire caulk or another listed material.
The schools I've wired, I ran my feeders to sub-panels under slab. Is it too late for you?
Besides, the other sub trades will have the same condition, right?

 

[pete m.]

I don't think you need to worry. Anytime you penetrate a fire wall, the annular space around the pipe, cable, or whatever will need to be properly filled w/ fire caulk or another listed material.
The schools I've wired, I ran my feeders to sub-panels under slab. Is it too late for you?
Besides, the other sub trades will have the same condition, right?

Thanks for the response. My concern is not with fire-wall penetrations but with the fact that these are separate buildings and compliance with articles 225.30, 225.32, 225.33, 225.34 and 225.36 to name a few are the concern.

Pete

 

[augie47]

Were the "separate structures" taken into account at all when installing the electrical. For instance, do the individual subpanels feed branch circuits within one structure or do they span structures.
If the branch circuits remained within the specific "buildings", the "special conditions" should take care of some of the problems.

 

[RB1]

Pete,

This is a judgement call. I once worked with a Chief Electrical Inspector and Building Official, that because of the presence of fire walls, considered feeders supplying equipment located on the other side of the fire walls as outdoor feeders and thus subject to the requirements of Article 225. I don't hold that view. Lets say I have an an A-3 occupancy in a 9,000 sq. ft. building of Type VB construction (no area increases). Because of the construction type I put in a fire wall to separate the Sunday school classrooms from the sanctuary. Does that make the safe disconnection of the electrical service to the building any more difficult than a 1,000,000 sq. ft warehouse with no fire walls? I don't think so.

When I read the scope of Article 225, I think of actual space separations that would make the safe disconnection of power to separate buildings impractical to personnel that are not familiar with the premises if the requirements of that article are not met. In the example given the service can be disconnected in the same manner as any other building.

I agree that for the purpose of the Building Code these are separate buildings. The judgement is whether or not these are outdoor feeders. That is your call.

 

[pete m.]

When I read the scope of Article 225, I think of actual space separations that would make the safe disconnection of power to separate buildings impractical to personnel that are not familiar with the premises if the requirements of that article are not met. In the example given the service can be disconnected in the same manner as any other building.

I appreciate your opinion on the matter. I am currently reviewing the electrical drawings for plan approval. I can agree with the logic you employ in your opinion although article 225 does not require a physical separation of buildings only a separate building.

Perhaps this is an issue that the appeals board needs to make a determination on.

Thanks to all, Pete

 

[RB1]

Pete,

I am also a Plans Examiner. I completely agree that these are separate buildings. But these are no more outside feeders than any other feeder run under a slab.

If you compartmentalize the hypothetical warehouse in my first post for insurance reasons, and have suitable fire-stopping methods for a feeder that passes through the compartments, are you going to require a disconnecting means at each compartment?

I think you must consider the intent of the code when it refers to "outside feeders" run between buildings.

Anyhow, thats why they have a Board of Appeals.

 

[augie47]

Pete,
I think the "exceptions" are often used to allow additional feeders on these buildings;
(B) Special Occupancies. By special permission, additional feeders or branch circuits shall be permitted for either of the following:
(1) Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants
(2) A single building or other structure sufficiently large to make two or more supplies necessary
(C) Capacity Requirements. Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 600 volts or less.

 

[pete m.]

Pete,
I think the "exceptions" are often used to allow additional feeders on these buildings;
(B) Special Occupancies. By special permission, additional feeders or branch circuits shall be permitted for either of the following:
(1) Multiple-occupancy buildings where there is no space available for supply equipment accessible to all occupants
(2) A single building or other structure sufficiently large to make two or more supplies necessary
(C) Capacity Requirements. Additional feeders or branch circuits shall be permitted where the capacity requirements are in excess of 2000 amperes at a supply voltage of 600 volts or less.

That may be a possible solution... I'll run it by the CBO and see what he says.

Thanks, Pete