When a motor starter fails in an industrial control panel, you are not just choosing any contactor. You have to match NEMA frame size, coil voltage, current rating, overload protection, and mounting style to the motor and enclosure. The Allen-Bradley 509-COB-A5H is a specific combination of those specs, and this review helps you decide whether this used starter belongs in your project.
Quick verdict
This is a used Allen-Bradley Bulletin 509 Series AC magnetic motor starter. It is a NEMA Size 2 unit rated for three-phase 60 Hz service at 45 full-load amps, and it is priced at $150.00. Removed from a decommissioned control panel with clean contacts, it is described as ready to install, which removes one layer of prep work. Because it is a magnetic starter, it uses a coil to pull the contacts closed, so it can be controlled from a remote push button or an automated control system.
Who it suits
This starter fits technicians and electricians working on industrial motor control panels that need a base-mounted contactor. The included overload relay block is a real convenience for a replacement job, since it saves you from sourcing that component separately. It also makes the unit a self-contained starter rather than a bare contactor. It is not the best fit for a project that demands brand-new, warranty-backed parts, or for someone who is not comfortable inspecting used electrical equipment.
What stands out from the listed details
The catalog number 509-COB-A5H identifies this as a NEMA Size 2 starter with a 480V coil, and the base-mounted design makes panel installation simple. The 45-amp full-load rating sets a clear boundary for the motor size it can handle. The base-mounted format keeps the unit easy to drop into an existing panel.
Meaningful trade-offs
This is a used product pulled from a decommissioned control panel, so you are taking on some uncertainty about internal wear and coil condition. The listed nominal input voltage is 460 V, and the coil is rated at 480 V; confirm both match your wiring before installation. No auxiliary contacts or accessories are listed, so plan to source those if needed. There is no warranty information, so your own inspection is the only safety net. Used contactors can also have plungers and springs that have seen years of cycling, so a bench test of the coil and contact continuity is worthwhile before you put it in service.
Bottom line
At $150.00, the Allen-Bradley 509-COB-A5H is a practical option for a controlled rebuild or replacement where you can do your own testing. The voltage ratings align with a specific range of three-phase motors. It is not the right choice when you need a new starter with a documented service history for a critical application. If you are willing to do the diligence, this starter gives you a solid foundation at a lower upfront price.
Product notes
Allen-Bradley 509-COB-A5H NEMA Size 2 Motor Starter Contactor 480V
The reason to choose this unit is the mounted overload relay block, which makes it a complete starter package compared with a bare contactor. The limitation is its used, decommissioned-panel history: you accept unknown wear and no stated warranty. If you are comfortable testing coils and contacts before energizing, this is a workable base for a rebuild.
