4.3 KiB
id, aliases, tags
| id | aliases | tags | |
|---|---|---|---|
| feeders |
|
Feeders
Info
Routing and Structural Considerations
Shear Walls
Shear walls, like those around stairwells and elevator shafts, may be routed through with special permission.
Post-Tensioned Slabs
[!example] STRUCTURAL SLAB IS AN 8-INCH THICK UNBONDED POST-TENSIONED TWO-WAY SLAB UNLESS NOTED OTHERWISE.
[!cite] Joel Jansen 2025-08-15, in reference to Belle Meade Plaza (pp.) No affect on takeoff. Routing in slab still possible.
[!cite] Joel Jansen 2025-08-21, in reference to Belle Meade Plaza (pp.) PT slabs do have some affect on takeoff. 3in conduit can not be run in an 11in PT slab.
Pan Deck Slabs
[!example] STRUCTURAL SLAB IS 3 1/2 INCHES OF NORMALWEIGHT CONCRETE ON 3-INCH COMPOSITE STEEL DECK UNLESS NOTED OTHERWISE.
[!cite] Joel Jansen 2025-08-15, in reference to Belle Meade Plaza (pp.) Do not route in slab.
Fire Rated Feeders
PDI estimating practice is to run all "emergency" feeds (life-safety or just standby) in a 2-hour rated assembly. This usually requires no change to takeoff for high-rises since electrical riser rooms are themselves fire-rated.
- RHW-2 insulated conductors in conduit -- "Lifeline Cable"
- 2-hour rated metal clad cable -- "Vitalink"
Formatting
All feeder takeoff descriptions should be prefixed with <parent> TO <child>
[!cite] Joel Jansen, in reference to Omni Hotels Raleigh, pp. It is acceptable to use typicals for identical feeders (i.e. meter centers fed from bus plugs) so long as the typical is in the Feeders
Area.
Sequence
1. Estimate preparation
Read about the project specifications and construction type:
- Deck thickness
- Wiring methods
- Conductor material
- Wire terminations (set-screw acceptable or compression required?)
Locate:
- Riser Diagram
- Feeder Schedule (if present)
- Main Electrical rooms and panel locations
2. Takeoff
Run parallel to building lines and route through corridors where possible.
Important
All takeoffs in Systems with names including "site" should be in "Site" Area, Phase, and Bid Item breakdowns.
For adjacent panels, use a minimum 10ft length.
Adders
Use the difference in elevation between equipment or 10ft, whichever is greater.
Add an additional 5ft (total 15ft) for site runs (primaries, secondaries, etc.).
Primaries
Usually only empty conduit if included.
Secondaries
Wiring on Vault Racks
Where secondary conductors run on racks in utility vaults manually set the length of conduit, measure the wire length, add 20ft in addition to previously mentioned adders.
Feeders
Area = "01 - Feeders/Risers Building"
for all feeders, no matter the location.
Bus Duct
COMMON ASSEMBLIES/DISTRIBUTION/BUS DUCT
Cable Support
[!quote] 300.19 Supporting Conductors in Vertical Raceways. (A) Spacing Intervals -- Maximum. Conductors in vertical raceways shall be supported if the vertical rise exceeds the values in Table 300.19(A). At least one support method shall be provided for each conductor at the top of the vertical raceway or as close to the top as practical. Intermediate supports shall be provided as necessary to limit supported conductor lengths to not greater than those values specified in Table 300.19(A).
[!cite] Table 300.19(A) Spacings for Conductor Supports
Conductor Size Aluminum or Copper-Clad Aluminum Copper 18 AWG through 8 AWG 100ft 100ft 6 AWG through 1/0 AWG 200ft 100ft 2/0 AWG through 4/0 AWG 180ft 80ft Over 4/0 AWG through 350 kcmil 135ft 60ft Over 350 kcmil through 500 kcmil 120ft 50ft Over 500 kcmil through 750 kcmil 95ft 40ft Over 750 kcmil 85ft 35ft
ITEM DATABASE/CONDUIT & FITTINGS/CABLE SUPPORT / WEDGES/... COMPLETE FITTING/...
Grounding
See grounding.
Sleeving
See sleeving.