Parallel feeders use more than one conductor set for the same feeder circuit. The sets connect to the same source and destination and work together as one designed installation. Large electrical systems may use this arrangement when the engineer determines it is suitable and the applicable requirements allow it.
On a one-line diagram, that entire connection may appear as a single feeder. In the building, it can require several large conduits leaving switchgear together, crossing a room or corridor, and entering a transformer or switchboard. The electrical drawing is simple. Finding room for the complete raceway group often is not.
Why Large Electrical Feeders May Use Parallel Conductors
A large load does not always lead to one practical conductor arrangement. The design may instead divide the feeder among multiple sets. That choice affects terminations, raceways, and field installation.
It is still one feeder circuit, not a collection of unrelated runs. Each set connects the same two points. Parallel conductors are not automatically right for every large load; that decision belongs to the electrical engineer.
The completed design gives the construction team the conductor sets, raceways, equipment, and connection points that must be built. From there, electrical feeder routing has to turn the diagram into an installable path.
Code Requirements Apply to the Whole Installation
The NEC includes specific requirements for conductors installed in parallel. These address conductor and installation characteristics and must be checked in the edition adopted for the project.
NFPA 70, the National Electrical Code, is the governing source. The BIM team models the issued design; it does not select conductor sizes or decide how many sets are needed.
One-Line Diagram vs Physical BIM Reality
The one-line might show this:
Switchgear → feeder → transformer
The model has to show something closer to this:
Switchgear → grouped conduits → support rack → bends → penetration → transformer
That difference drives the coordination effort. A bank of parallel conduit runs needs room at the equipment, along the route, and through every bend. A clear corridor centerline does not help if the equipment entry, wall sleeve, or final bend cannot accept the full group.
Conduit modeling shows the actual diameter and bend geometry instead of treating the feeder as a line. In an electrical room model, the team can review equipment exits, entries, access zones, and nearby gear together.
Parallel Feeders Must Be Routed as One System
Routing every raceway separately can produce a model that connects both ends but cannot be installed cleanly. The group needs a common route, an intentional rack order, coordinated bends, and a workable support approach.
The route may pass through sleeves, risers, pull points, or an underground duct bank. Each transition can affect supports, penetrations, pulling access, and assemblies planned through electrical BIM prefabrication.
Above a corridor, the bank competes with ductwork, piping, cable tray, lighting, and fire protection. Below grade, underground electrical BIM accounts for duct-bank geometry, sweeps, foundations, and utilities. BIM coordination services keep the raceways grouped while the route changes around them.
Installation sequence matters too. A route may become difficult once a duct main or pipe rack is in place, so the model should reflect how crews will assemble the work.
Data Center Example: One Feeder Becomes a Conduit Bank
On a data-center project, the one-line shows one feeder between a switchboard and a downstream transformer. The corridor selected for the route appears wide enough during early planning.
In the model, the feeder becomes several large raceways on a shared rack. The bank is wider than expected, its bends reach a mechanical pipe, and structure blocks the approach to the transformer entry.
The Data Center BIM Services team reviews the bank as a group. Before fabrication, the rack shifts, the bends are revised, and the penetration is coordinated with structure. The electrical crew now has an installable route.
Electrical BIM Services model what the issued design requires. They do not calculate ampacity or determine conductor quantity. They coordinate the resulting equipment, raceways, supports, and openings.
Parallel Feeders Need Physical Space, Not Just Diagram Space
Parallel feeders may be part of a distribution arrangement selected by the project engineer. For construction teams, one diagrammed feeder may become a substantial conduit bank.
Early routing must cover rack width, bends, entries, supports, penetrations, other trades, and installation sequence. Coordinating those details before fabrication keeps an oversimplified line from becoming a field problem.
Frequently Asked Questions
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What are parallel feeders?
They use multiple conductor sets connected between the same source and destination as one feeder circuit, where permitted by the design and applicable requirements.
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Why are conductors run in parallel?
An engineer may use parallel conductor sets for a large load when that arrangement suits the distribution design, equipment terminations, raceway plan, and installation conditions.
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When are parallel feeders used?
They are common in large electrical systems serving substantial loads, including data centers, industrial facilities, and major commercial buildings. Their use is project-specific.
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Do parallel conductors need to match?
The NEC applies requirements to key conductor and installation characteristics within the parallel arrangement. The adopted NEC edition and approved project design must be checked for the exact requirements.
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Why are parallel feeders difficult to coordinate in BIM?
One diagrammed feeder can represent several physical raceways. Together they require considerable space for racks, bends, supports, penetrations, equipment entry, and installation access.
Does One Feeder Line Become a Congested Route in the Model?
