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