OCCUPANCY (PER IBC) of MCC

[6simplemachines]

Hello, working on the design of an MCC in a predominantly H-3 occupancy. First question concerns occupancy of the MCC. Our arch group typically assigns an S-2 to Electrical Rooms. It is fairly sizeable...so it is not under the 10% threshold for accessory/incidental use. IBC calls for a 2-Hr separation between and S-2 and an H-3.

Second question: H-3 is sprinklered. Client wants no sprinklers in the MCC. by NFPA 13- Section 8.15.10.1 Installation of Sprinkler Systems, requires sprinklers in all spaces in a building protected with sprinklers, including electrical rooms. According to Section 8.15.10.3, however, sprinklers may be eliminated in electrical rooms if the room is dedicated solely to electrical equipment; only dry-type electrical equipment is used; the equipment is installed in a two-hour fire-rated enclosure including protection for penetrations; and no combustible storage is permitted in the room

Client does not see the reason to rate the partitions at all...

it's 475 sf space...transformers sit outside the space.

Thx!

 

[charlie b]

Not sure I can be of assistance on this one. But for clarity of the question, let me mention that, to me at least, "MCC" means "motor control center." That is a piece of equipment. It is not the room in which any piece of equipment is located. Are you talking about an electrical room in which an MCC is to be located?

 

[don_resqcapt19]

Not sure I can be of assistance on this one. But for clarity of the question, let me mention that, to me at least, "MCC" means "motor control center." That is a piece of equipment. It is not the room in which any piece of equipment is located. Are you talking about an electrical room in which an MCC is to be located?

While technically the MCC is the equipment, it is very common in this area to call the room the MCC.

 

[mgookin]

Hello and welcome to the forums.

It sounds like your client has two options, neither of which are to his satisfaction.

Maybe you could suggest an alternative fire suppression system in the electric room.

 

[don_resqcapt19]

The sprinklers are in the electrical room, not to protect the electrical equipment, but to protect the rest of the building from a failure of the electrical equipment. If the electrical room is hot enough to activate the sprinkler heads, the electrical equipment is already junk.

 

[Jraef]

The sprinklers are in the electrical room, not to protect the electrical equipment, but to protect the rest of the building from a failure of the electrical equipment. If the electrical room is hot enough to activate the sprinkler heads, the electrical equipment is already junk.

I have made that argument, almost verbatim, to a Consulting Engineer for the City of San Francisco. I was being told to REMOVE existing sprinklers in an MCC room because "the water will cause the equipment to short out". My point was that one just made: the sprinklers will only come on AFTER the fire has ALREADY happened. If a fire happens in an MCC, something SERIOUSLY wrong has taken place and a protective device somewhere up stream has failed to clear it. At that point, there is ALREADY nothing left to save; nothing in an MCC is salvageable after a fire, because you have no way of knowing if bus bracing has been compromised even if it didn't actually burn. The heat in the enclosure will be so extremely above design limits that no amount of inspection or testing will be sufficient to ensure safe re-use.

It was an utterly pointless exchange. I took out the sprinkles, which of course triggered a re-inspection and certification of the fire protection system, none of which I had budgeted for in the project. Lesson learned.