Res. vs. Comm Services - A "Loaded Question"
Res. vs. Comm Services - A "Loaded Question"
Residential -vs- Commercial Services... almost worthy of 2 more separate threads!!!
IMO, There is no definition per Capacity, Voltage, or Phase (Single Phase or Poly Phase) that could be applied to a given Service, in order to classify "Residential", "Commercial" or "Light Industrial".
A Manufacturer of Service Equipment might list certain types as "Residential" or "Commercial", per qualifying specifications & etc., so this could be used for one valid example.
Another valid example would be the base classification of a "Customer", and the Service Classification, as indicated by a governing Utility - verbally, and in published ESR Manuals ("ESR" = Electrical Service Requirements).
As to the NEC (NFPA 70), the differences of Residential -vs- Commercial / Industrial are mostly reflective of Load Calcs (Article 220), with a few specifics found in Chapters 3 and 6.
IMO, the basis is Trade-Specific Nomenclature.
In the >26 Years of Trade experience - in the field and as Electrical Designer / Engineer, the variety of Services on Projects I have dealt with have been more a result of:
"Application / Capacity requested -vs- the Footprint (Building Square Footage), according to the Area (Zoning)"
One example:
240/120V 3 Phase 4 Wire Delta Transformer Setup - >= 150 KVA, feeds:
A: Eight to Ten, 600 to 800 Sq. Ft. Single Family Dwellings;
B: Four, 1K Sq. Ft. Light Industrial Units - each Unit having a 100 Amp 120/240V 1 Phase 3 Wire Service,
C: One 15K Sq. Ft. Commercial Occupancy (Single Tenant Office) - with a 600 Amp 240/120V 3 Phase 4 Wire Service.
Another example:
208Y/120V 3 Phase 4 Wire Wye Transformer Setup - >= 150 KVA, feeds:
A: Single Family Dwellings - Services = 120/208V 1 Phase 3 Wire, with capacity of 100 Amps and 200 Amps,
B: Strip Mall Tenant Suites - average size = 2K Sq. Ft., each having 100 Amp, 208Y/120V 3 Phase 4 Wire Panelboard Feeders - fed from a 600 Amp Service.
Have seen many Commercial Tenants with 120/240V 1 Phase 3 Wire Services (max. 200 Amps), and seen Residential Customers with 240/120V 3 Phase 4 Wire Delta Services, or 208Y/120V 3 Phase 4 Wire Services (>600 Amps)
The Playboy Mansion "West" (Southern California) has a 4000 Amp, 480Y/277V 3 Phase 4 Wire Service, fed by a Utility-Owned 750 KVA Transformer Setup.
Just completed Design & Engineering for a Zoning "M1" (Light Industrial) project, which has the circa 1950's "Dual Services" (the old-timers will know about these).
These Customers have Two separate Service Sections; each having a KWH Meter and Service Disconnect, which are fed from a common 240/120V 3 Phase 4 Wire Delta Transformer Setup.
One Service is a 120/240V 1 Phase 3 Wire Section + Meter, identified as the "Lighting" Service. The Grounded Conductor is brought to this Service Section only, where it is bonded to the GES as usual.
The other Service is a 240V 3 Phase 3 Wire Section + Meter, identified as the "Power" Service. No Grounded Conductor at this Service. The Section is bonded to the "Lighting" Section's Grounded Conductor at the same point as the Main Bonding Jumper.
Dealt with more than 30 Projects having these "Dual Services" in the past >26 Years.
At the same time, was performing Project Management for a "Beyond Overkill" 5,500 Sq. Ft. new Single Family Dwelling.
This Project has (2) 400 Amp 120/240V 1 Phase 3 Wire Services, each Service fed by a Dedicated Utility Transformer (One 50 KVA Transformer per Service).
I will stop boring everyone with this, and let others contribute!
Scott
