Case study · 2024–2026
Transfer-switch and breaker enclosures for standby-power installations
Standby and backup power systems (generator and transfer-switch installations). Scope: electrical layout and drawings, ABB component selection, UL 508A shop assembly, test and ship.
The challenge
A power-systems provider that installs generators and transfer switches needed enclosed transfer-switch and breaker assemblies built to its specifications. Examples are a manual transfer switch, or a box that splits one generator feed into two breaker-protected outputs. Lead time was critical.
The provider needed a shop that could:
- turn its sketches into drawings;
- source the switching devices;
- build each enclosure quickly.
What we did
- Built an enclosed 200 A manual transfer switch. We offered a shop-built version to cut the lead time. It used an ABB OT-series 200 A three-pole switch with external handle and shaft, in a Hammond enclosure. We issued the panel layout drawing and neutral-connection details with the order. The unit shipped in early 2025.
- Delivered a 200 A transfer-switch panel in a Type 12 enclosure in 2025, along with two dual-150 A circuit breaker boxes. All three were assembled and tested in our UL 508A shop and shipped together as one complete order.
- Designed the next dual-breaker enclosure with the contractor (2026). This version is a NEMA 3R, 20 × 20 × 8 enclosure with:
- two 125 A three-pole breakers;
- a single generator feed entering at the bottom through a distribution block;
- two breaker outputs leaving through the top toward two automatic transfer switches;
- an isolated neutral bar tying the generator neutral to both outputs;
- one ground lug sized for three #6 conductors.
Our project engineer took the drawing through several quick revisions with the provider and its contractor. The revisions confirmed the conductor sizes, neutral and ground details, and the inverted (bottom-in, top-out) layout before the order was placed.
The result
The provider has returned for each new variation, from a manual transfer switch to dual-breaker distribution enclosures in indoor and outdoor ratings. The NEMA 3R unit is scheduled to ship in late 2026.
What it shows: custom power-distribution enclosures built to a contractor's needs, ABB switching and protection devices, drawing collaboration with the end installer, and quick small-quantity builds from our UL 508A shop.