2-Wire RS485 Surge Protector (Industrial / Passive)


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The SPD-485-1 is a passive, rugged, industrial-grade, 2-wire RS485 surge protector that can be used to limit the voltage surges and spikes introduced to the RS485 data lines. This industrial RS485 surge protector features 3-stage surge protection – Gas Discharge Tubes (GDT), protection resistors, and Transient Voltage Suppressors (TVS) - for maximum protection. The SPD-485-1 is designed to connect in series to the input of the protected equipment; when a high-voltage surge is introduced into the input, the GDT conducts electric current after becoming ionized, which in turn discharges the high-voltage surge to the earth ground. The excessive voltage will be further clamped to a safe range that the equipment can accept by the TVS. This industrial 2-wire RS485 surge protector features passive circuitry designs and thus requires no external power; it supports data rates up to 10Mbps and can be used for protecting RS485, telephone, facsimile, and other communication equipment. This product comes with a dedicated cable lug for solid earth ground connections and can be mounted directly onto a standard 35mm DIN rail, making it an ideal solution for heavy-duty industrial applications.

CommFront's products quality is ensured by our ISO-9001 quality control system (Cert No. SG12/04213, strictly certified by SGS), and we back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee.


  • Rugged industrial-grade 2-wire RS485 surge protector (passive).
  • Protects RS-485, telephone, facsimile and other communication lines.
  • 3-stage surge protection.
  • 3-way self-clamping terminal blocks for data lines and the shield wire.
  • Dedicated cable lug for solid earth ground connections.
  • Passive circuitry, no power is required.
  • Supports data rates up to 10Mbps.
  • Direct DIN-Rail mounting.
  • Operating temperature: -40°F to 185°F (-40°C to 85°C).
  • Surface Mount Technology manufactured to RoHS and ISO-9001 standards.
  • Test Standards: IEC61643-21 / EN61643-21.
  • 5-year manufacturer’s warranty.


Compatibility: EIA/TIA RS-485 standard
Protection: 3-stage surge protection (Gas Discharge Tubes, Protection Resistors, and Transient Voltage Suppressors)
Power Source: Passive device, no power required
Clamping Voltage (stage 1): 30 V
Series Resistance (stage 2): 2.2 Ohms
Clamping Voltage (stage 3): 6 V
Response Time: ≤1ns
Insertion Loss (10MHz): ≤0.5dB
Data Rates: Up to 10Mbps
Cable Lug for Earth Ground: Dedicated cable lug for earth ground connection (cable size: up to 12AWG / 3.3mm2)
Terminal Blocks: 3-way self-clamping terminal blocks (wire gauge: 16-26AWG)
Dimensions (H x W x D): 3.0 x 1.9 x 1.0 in (75 x 49 x 25 mm)
Mounting: Direct 35mm DIN-rail mounting
Weight: 3.0 oz (84 g)
Operating Temperature: -40°F to 185°F (-40°C to 85°C)
Operating Humidity: 5~95% RH (no condensation)





CommFront products are strictly certified by SGS and/or TUV - the Nationally Recognized Testing Laboratories [NRTLs] in North America (approved by OSHA) and the Notified Bodies in the European Union. Learn More




CommFront products are designed and manufactured to ISO 9001 standards. Our quality control system is strictly certified by SGS (Cert No. SG12/04213). Learn More




CommFront products have been proven to be reliable. We back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee. Learn More

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