The Simplex 734-257 is a factory wiring harness for 120V power distribution between a Simplex PDM (power distribution module) and an EPS (extender power supply). As a result, it carries the AC supply leg the panel’s downstream supply needs.
Specifically, the harness terminates to the connector landings on each module. In addition, the assembly is offered as a service-replacement spare for installations that already include a Simplex PDM-to-EPS power chain.
When You Need the Simplex 734-257
Field techs reach for this harness during board-level service. For example, when a damaged factory harness must be swapped during a panel rebuild or after a power-supply replacement. Also, it shows up on parts lists for major retrofit work in Simplex 4100/4100U-family installations.
First, verify the existing module pair (PDM and EPS) and the 120V input designation. Then, match the harness to the panel’s documented spare-parts list before ordering. Finally, follow the manufacturer’s service literature for power-down and reconnection procedures.
Key Features
- Pre-terminated harness — PDM to EPS, 120V leg
- Factory replacement assembly for Simplex panel power chains
- Used in service, retrofit, and rebuild scenarios where the original harness is damaged
Specifications
- Manufacturer: Simplex
- Part number: 734-257
- Function: Harness, PDM to EPS, 120V
Order from Life Safety Consultants
The 734-257 is a low-volume, high-importance spare. Furthermore, having the correct factory harness on the truck avoids the temptation to field-fabricate AC wiring inside a UL-listed fire alarm control unit. We stock these alongside other Simplex panel-internal cables, displays, and power supplies.
For more information, contact the Life Safety Consultants team at (888) 557-0558, or email us at: sales@lifesafetycom.com
Additional information
| Weight | 0.65 lbs |
|---|---|
| Dimensions | 8.6 × 6.2 × 4.9 in |
| Condition | New |
| Manufacturers | Simplex |
| Part Type | Replacement Part |







