SECTION 262400 - SWITCHBOARDS AND PANELBOARDS



This master should be used by designers working on Port of Portland construction projects and by designers working for PDX tenants (“Tenants”). Usage notes highlight a few specific editing choices, however the entire section should be evaluated and edited to fit specific project needs.

SECTION 262400 – SWITCHBOARDS AND PANELBOARDS

GENERAL

1. DESCRIPTION

A. This section describes materials and installation for switchboards and panelboards.

2. REFERENCES

A. NEC: National Electrical Code

3. SUBMITTALS

A. Coordination Study:

1. Submit a coordination study for the electrical overcurrent devices to assure proper equipment and personnel protection.

2. Present an organized time-current analysis of each protective device in series from the individual device back to the source. Reflect the operation of each device during normal and abnormal current conditions.

3. The study shall be prepared by qualified engineers of the switchgear manufacturer, Electro-Test, Electrical Systems Analysis, Inc., or pre-bid approved equal. Provide all pertinent information required by the preparers to complete the study.

4. Include a system one-line diagram and protective coordination curves.

a. The coordination curves shall determine the required settings of protective devices to assure selective coordination. The curves shall graphically illustrate on log paper that adequate time separation exists between series devices. Plot the specific time-current characteristics of each protective device so that all upstream devices are clearly depicted on one sheet.

b. Show the following specific information on the coordination curves:

1) Device identification.

2) Voltage and current ratio for curves.

3) 3-phase and 1-phase ANSI damage points for each transformer.

4) No-damage, melting, and clearing curves for fuses.

5) Cable damage curve.

6) Transformer inrush points.

7) Maximum short circuit cut-off point.

c. Develop a table that summarizes the settings selected for the protective devices. Include the following:

1) Device identification.

2) Circuit breaker sensor rating, long-time, short-time, instantaneous settings, and time bands.

3) Fuse rating and type.

4) Ground fault pickup and time delay.

B. Product Data: Submit product data for each type of switchboard, panelboard, overcurrent protective device, accessory and component indicated. Include dimensions and manufacturers’ technical data on features, performance, electrical characteristics, ratings and finishes.

C. Closeout Submittals:

1. Operation and maintenance data.

2. Warranty information.

PRODUCTS

1. ACCEPTABLE MANUFACTURERS

A. Acceptable manufacturers for switchboard, panelboard, and all associated products are:

1. General Electric Co.: Electrical Distribution & Control Division.

2. Siemens Energy & Automation, Inc.

3. Square D/Group Schneider.

4. Eaton Cutler-Hammer.

5. Pre-bid approved equal.

2. switchboards

A. General: Panels shall be sectionalized, free-standing or wall-mounted, front-operated circuit breaker type, fully enclosed with bussing provisions for future extension. Overcurrent protection ratings shall be as noted on the drawings. All devices shall be capable of interrupting the fault current available.

B. Bus Work:

1. Copper, sized as shown on the drawings, 100 percent neutral with a maximum hot-spot temperature rise of 65ºC above an ambient temperature of 40ºC under continuous full load current and rated to withstand a minimum of 50,000 A fault currents.

2. Include bussing provisions for mounting future devices in all potential spaces. Where panel configuration provides additional spaces within a section, these spaces shall be bussed to receive future devices. Make provisions for future extension of bussing. Provide a copper ground bus in bottom of enclosure.

C. Assemblies:

1. Primed and finished with not less than two coats of light grey enamel paint. Assemblies rated over 1000 amperes shall be of free-standing construction.

3. BRANCH PANELBOARDS

A. Branch circuit panels shall be bolt-in circuit breaker type with copper bussing. Panels shall be fitted with flush lift latches and locks keyed alike. Deliver all panel keys at completion of the project.

B. Circuit breakers shall be molded case, thermal magnetic or solid state type as required to provide coordination. Breakers shall have short circuit capacity rating to withstand the maximum short circuit duty which can be expected at the breaker location in the electrical system. Breakers mounted in branch panelboards shall be of the bolt-in type. Minimum short circuit rating for any circuit breaker: 10,000 AIC for 120V and 208V breakers, 14,000 AIC for 277V and 480V breakers.

C. Branch circuit breakers shall be identified with individual circuit numbers adjacent to each breaker and with a typewritten card to identify the load controlled by that breaker.

D. Where required, panels shall have main circuit breakers, sized as scheduled, mounted behind door at top of panel (back feeding of branch breaker is not acceptable).

E. Wiring gutters shall be a minimum of 4 inches wide except where feeder conductors enter, where a minimum of 6 inches clearance shall be provided. Feeder conductors shall enter directly in line with lug terminals wherever practicable. Provide separate feeder lugs and studs for each feeder conductor.

F. Panels shall have door-in-door construction. Flush panels shall have flush doors with concealed hinges and mounting clamps. Surface panels shall have metal face trims with no sharp edges or corners. Factory finished surface panel tubs shall match face trim.

G. Panels shall have a grounding bus with termination capacity for the grounding conductor sized for the branch circuit equipment grounding conductors as shown or noted. Isolated ground bus shall be insulated from the panel cabinet.

H. Provide mounting brackets, bus connections, and necessary appurtenances required for future installation of devices.

EXECUTION

1. INSTALLATION

A. Install the equipment as shown on the drawings, parallel and square with the building lines. Provide code clearances as required.

B. Install a spare 3/4-inch conduit from flush panels for every three single-pole breakers or spaces provided. Terminate conduits above accessible ceiling or as directed.

C. Neatly lace and secure the conductors of the feeder circuits individually at maximum 2 foot intervals. The cable lugs shall not support the weight of the cables.

D. Concrete Pads:

1. Provide minimum 3-inch-thick concrete housekeeping pads under all free-standing pieces of switchgear. Extend pads a minimum of 2 inches beyond the edges of the equipment.

E. Equipment Tests:

1. Perform tests on the ground fault protection system in accordance with the manufacturer’s instructions. Record results and submit with final warranty.

2. Adjust breaker settings per recommendation of coordination study and test all ground fault settings as required by NEC.

2. identification

A. Identify field-installed conductors, interconnecting wiring and components; provide warning signs as specified in Division 26 Section “Identification for Electrical Systems.”

B. Enclosure Nameplates: Label each enclosure with engraved metal or laminated-plastic nameplate as specified in Division 26 Section "Identification for Electrical Systems."

3. CLEANING

A. On completion of installation, inspect interior and exterior of switchboards and panelboards. Remove paint splatters and other spots. Vacuum dirt and debris; do not use compressed air to clean. Repair exposed surfaces to match original finish.

END OF SECTION 262400

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