Multiple Services for Large Buildings that have high load

[GlenSeilerPE]

Hi folks! For large buildings where the load is expected to be larger than one utility transformer and service, what kind of requirements do we run into? It's my opinion that NEC allows this per the below. However, I want to solicit feedback from the group on other code concerns. I've heard some say a fire separation is required, however I don't see where that requirement would come from.

NEC 230.2 (B) Special Occupancies. By special permission, additional services are permitted for:

(1) Multiple-occupancy buildings where there’s no available space for supply equipment accessible to all occupants, or

(2) A building or other structure so large that two or more supplies are necessary.

 

[augie47]

Fairly common occurrence here. At times fire seperation is present but not NEc required

 

[charlie b]

I've designed large, open warehouses with more than one service, with no separation at all.

 

[electrofelon]

Hi folks! For large buildings where the load is expected to be larger than one utility transformer and service, what kind of requirements do we run into? It's my opinion that NEC allows this per the below. However, I want to solicit feedback from the group on other code concerns. I've heard some say a fire separation is required, however I don't see where that requirement would come from.

NEC 230.2 (B) Special Occupancies. By special permission, additional services are permitted for:

(1) Multiple-occupancy buildings where there’s no available space for supply equipment accessible to all occupants, or

(2) A building or other structure so large that two or more supplies are necessary.

I agree with the others, no fire separation required. I just wanted to point out 230.2(C)(1) which I think fits your description a little better than the section you quoted, and no special permission required.

 

[garbo]

The large 12 story hospital that I retired from had a dual 13.2 KV service in the original building and a dual 13.2 KV service in a 12 story addition. Each floor above the three level basements were connected with at least two short hallways. Each building had thier own generators.

 

[infinity]

With large commercial buildings it's not uncommon to have 4, 5, or 6, 4000 amp services all in a common service room which satisfies the service disconnect grouping rule.

 

[kwired]

A somewhat common misunderstanding is that those multiple services when allowed need to be grouped together, that is not true.

You do need to post information at each location stating where all the other services are located though.

 

[kwired]

With large commercial buildings it's not uncommon to have 4, 5, or 6, 4000 amp services all in a common service room which satisfies the service disconnect grouping rule.

Only the 1-6 disconnects per service need grouped. If you are allowed more than one service the additional services do not need to be in same area as the first one.

 

[kwired]

I've seen ~ half mile long buildings that have a service on each end of the building. This can be compliant with some the allowances or exceptions in 230.

 

[infinity]

Only the 1-6 disconnects per service need grouped. If you are allowed more than one service the additional services do not need to be in same area as the first one.

That's correct. It's what I meant to say but didn't.

 

[jim dungar]

I've designed large, open warehouses with more than one service, with no separation at all.

The last one I worked in had 7 services, plus one per out building.
Two service mains were located within 4ft of each other, the other were hundreds of feet apart. Basically, one per side plus office, maintenance, and refrigeration.

 

[GlenSeilerPE]

I agree with the others, no fire separation required. I just wanted to point out 230.2(C)(1) which I think fits your description a little better than the section you quoted, and no special permission required.

Yes, good point:

(C) Capacity Requirements
Additional services shall be permitted under any of the following:

1. Where the capacity requirements are in excess of 2000 amperes at a supply voltage of 1000 volts or less

 

[Knightryder12]

I designed a 375K sq. ft. bldg. with 6 services. Only 2 of the 6 were close. The 4 others were very far apart.