Where more than one generator backs up a facility, a paralleling switchgear lineup synchronizes them, shares the load and feeds the distribution. Hospitals, water and wastewater plants, campuses, industrial facilities, telecom hubs and data centers all have them, and the lineups are built by switchgear packagers who design the controls and buy the enclosures. This guide covers what those enclosures are and how they are sourced.
Switchgear packager or genset dealer sourcing paralleling lineup enclosures? Call 601.892.5017 or email collin.t@fabtekindustries.com — send a print and a quantity and we’ll quote it.
- A paralleling lineup is metal-enclosed switchgear: generator breaker sections, a master control section and distribution sections on a common bus.
- The master control cabinet is the differentiator — controls, HMI, metering and an operator who stands in front of it during an outage.
- Outdoor lineups go in a walk-in housing or E-Room, often beside the generator yard.
- Packagers buy the enclosures per project to a standard section family, with the control section customized.
Anatomy of a paralleling lineup
The lineup is low-voltage (or medium-voltage on large systems) metal-enclosed switchgear: a breaker section per generator with the generator breaker and its controls, a master section with the paralleling controller, HMI, synchronizing and protective relays and the utility interface, and distribution sections with feeder breakers or automatic transfer switch connections, all on a common bus. The sections are built as described in metal-enclosed vs. metal-clad switchgear and switchboard sheet-metal kits; FabTek builds them on the switchgear enclosure line.
The master control section
- HMI and controls — door-mounted touchscreen, pushbuttons, selector switches and indicators at operator height, with cutouts to the device templates and a clear door panel layout.
- Metering and relays — door-mounted meters and protective relays, or a separate instrument door above the breaker compartment.
- Control compartment — a low-voltage compartment barriered from the bus and breakers for the PLC, terminal blocks and wiring, with its own door.
- Utility interface — space and cutouts for the utility’s metering or protective relay where the system closes to the grid.
- Lighting and work space — on walk-in lineups, operator lighting at the master section and a writing surface.
Outdoor lineups
Many paralleling systems live next to the generators, outdoors, in a walk-in enclosure or an E-Room: the lineup inside, an operating aisle in front, personnel doors at the ends, lighting, heating and ventilation, and the generator feeders entering from below or through the walls. The requirements are those in outdoor walk-in switchgear enclosures, with one addition: the housing should be sized so the master section’s operator has room to work with the door open and someone else in the aisle. Larger systems with transformers and distribution become E-Rooms.
Bus and cable entries
Generator feeders are large — parallel conductors per phase or bus duct from each set — and they enter at the breaker sections, so each section’s cable compartment and entry plate are sized to the feeder and the generator’s location. Distribution leaves by cable or bus duct from the distribution sections. The packager’s drawings set the entries; the fabricator builds the compartments, plates and bus duct flanges, and FabTek can supply the bus duct housings and bus bar alongside the sections.
How packagers source the enclosures
A paralleling system is a project, not a product, but the sections are a family: the packager standardizes its breaker and distribution sections and customizes the master section’s door and control compartment per job. The fabricator holds the section family drawings, builds the standard sections from stock programs, and builds the master section to the job’s panel layout, so the enclosure lead time on a project is the master section’s. Sourcing follows the switchgear enclosure RFQ checklist; the data-center-specific demand for these lineups is in the data center power chain, and the broader sector in generator enclosure sourcing.
Nobody notices the paralleling switchgear until the utility goes down. Then the only thing in the building anyone cares about is the master section, and the person standing in front of it.
FabTek Industries fabricates paralleling switchgear and distribution enclosures — generator breaker and distribution sections from a standard family, master control sections to the job’s panel layout, outdoor walk-in housings and E-Rooms — to packager prints, powder-coated in-house, under an ISO 9001:2015 quality system with AWS-certified welding, from four production sites in Hazlehurst, Mississippi. See switchgear enclosures, how we work with electrical OEMs, or send us a lineup drawing.
Working on something like this? Send a print or a scope — pricing and lead time within one business day, from four Mississippi plants.
Frequently asked questions
What is paralleling switchgear?
A metal-enclosed switchgear lineup that synchronizes two or more generators, shares load between them and feeds the facility’s distribution: a breaker section per generator, a master control section with the paralleling controller and HMI, and distribution sections on a common bus.
What is different about the master control section enclosure?
It carries the operator interface — door-mounted HMI, controls, metering and relays laid out at operator height — and a barriered low-voltage control compartment for the PLC and wiring, customized per project while the breaker and distribution sections follow a standard family.
Are paralleling lineups installed outdoors?
Often, next to the generator yard, in a walk-in enclosure with an operating aisle, personnel doors, lighting, heating and ventilation, or in an E-Room when transformers and distribution are included.
How do switchgear packagers buy paralleling enclosures?
As a standard section family built from stock programs, plus a master control section fabricated to each job’s panel layout, so the project’s enclosure lead time is set by the master section.
