Product Overview
Struthers-Dunn B58XDX Four Pole Industrial Control Relay, 125V Coil, Original Box
Condition
Unused, new old stock. The packaging has wear from storage. The relay is shown out of its box: the black phenolic base carries a molded S-D 70 roundel, the screw terminals and contact blades are bright bare metal with no corrosion or pitting visible, and the two black molded coil bodies and their black insulated jumper leads are present and undamaged on the outside. The coil windings themselves are enclosed in the molded coil bodies and cannot be inspected, and the relay has not been powered or continuity tested. The number 8434 is hand marked in white on one edge of the base. The back of the base shows light surface scratches and scuffing. The dark blue Struthers-Dunn box has soft corners and edge wear, with the end label stamped B58XDX 125 V 60 CY still fully legible.
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Product Overview
The Struthers-Dunn B58XDX is a heavy-duty open-frame control relay built for industrial panels, motor control, and power system switching. The nameplate riveted to the base reads STRUTHERS-DUNN INC. B58XDX, V. COIL CY 125 60, VOLTS CONTACTS AMPS 115 AC 6, so this unit is a 125 volt 60 cycle coil with contacts rated 6 amps at 115 volts AC. Four contact stacks sit above the phenolic base, with all of the screw terminals brought out on the front face; the back of the base is plain apart from recessed holes and the corner mounting holes. Four stacks is consistent with a 4PDT arrangement. It is built to the same open-frame pattern as the 219-series relays used in light rail, power generation, and heavy machinery control, and it is cataloged under NSN 5945-00-066-8560.
Key Features
- Model: Struthers-Dunn B58XDX (NSN 5945-00-066-8560)
- Coil, per nameplate: 125 V, 60 cycle (box end label stamped 125 V 60 CY)
- Contacts, per nameplate: 115 V AC, 6 amps
- Contact configuration: four contact stacks visible, consistent with 4PDT; pole count is not stated on the nameplate
- Construction: black phenolic mounting base, bright plated screw terminals (plating material not stated), open frame
- Base markings: molded S-D 70 roundel; 8434 hand marked in white on one edge
- Mounting: four corner holes in the phenolic base; earlier listing data gives 0.188 in holes on a 3 in x 2 in pattern, not measured on this unit
- Dielectric withstand: about 1,500 Vrms between coil and contacts (earlier listing data, not confirmed on this unit)
- Insulation resistance: 1,000 megohms or better at 500 VDC (earlier listing data, not confirmed on this unit)
- Operating range: -20 C to +60 C on AC, storage -40 C to +105 C (earlier listing data)
- Note: earlier listing text cited switching up to 10 A; the nameplate on this unit reads 6 amps. Not confirmed - verify against the datasheet before use
Applications
- Maintenance electrician keeping a 1970s motor control panel original instead of retrofitting a modern socket relay and adapter plate
- Power generation technician swapping a failed control relay on legacy switchgear where the 125 V control bus is not going anywhere
- Rail and transit shop rebuilding a control cubicle that still runs its interlocks on 60 cycle AC control power
- Collector or restorer of mid-century industrial control gear who wants a Struthers-Dunn unit that still has its original box
Frequently Asked Questions
What exactly does the nameplate say?
STRUTHERS-DUNN INC., B58XDX, V. COIL CY 125 60, VOLTS CONTACTS AMPS 115 AC 6. In plain terms: a 125 volt 60 cycle coil, with contacts rated 6 amps at 115 volts AC. The box end label is stamped B58XDX 125 V 60 CY, so the box and the part agree.
Is this definitely a 4PDT relay?
Four separate contact stacks are visible on the frame, each with its own screw terminals on the front face of the base, which is consistent with a 4-pole double-throw arrangement. The nameplate does not state the pole count, so confirm the contact form against the datasheet or the NSN listing before you commit it to a control scheme.
Will it work on a 120 V control circuit?
Not confirmed here. The nameplate on this unit reads 125 V, 60 cycle, and the earlier listing described the coil as suited to a 120 V 60 Hz supply. Check the coil voltage tolerance against the datasheet before you energize it on a nominal 120 V bus.
What is included?
One Struthers-Dunn B58XDX relay and the original blue S-D box shown in the photos. The box has storage wear. No mounting hardware, wiring, socket, or documentation is included.
Why buy a single relay here instead of a bulk lot somewhere else?
Because a panel repair needs one relay, not ten. PartsMine sells the exact quantity you need, whether that is one piece for a specific fix or two for a spare on the shelf, instead of forcing a lot of 10 or 50 on you. Shipping is $8 flat rate and free over $28, same or next business day from Idaho, so a single relay usually lands well under the cost of a forced-quantity lot.
S-D 70 is molded right into the base, and the blue box it came in has been softening at the corners ever since. Somewhere out there is a control cabinet that never stopped speaking 125 volts and 60 cycles, and this one has been waiting to answer.
