PRODUCT OVERVIEW The Murphy ES2P-100 (Part Number 05701858 / 05-70-1858) is a genuine Murphy by Enovation Controls 2-wire ungrounded resistive pressure sender rated at 100 PSI maximum. This pressure sender is designed for use with Murphy EG Series Swichgage instruments and CAN I/O modules, providing accurate resistive pressure readings for engine oil pressure monitoring, hydraulic systems, and other critical pressure applications on industrial engines, generators, compressors, and equipment. The ES2P-100 uses a standard 1/8-27 NPT thread connection and a 240-to-33 ohm resistance output. If you are searching for Murphy ES2P-100, Murphy ES2P100, Murphy 05701858, Murphy 05-70-1858, FW Murphy pressure sender, Murphy 2-wire pressure sender, Murphy 100 PSI pressure sender, Murphy Swichgage pressure sender, Onan 0193-0430-01, Onan pressure sender, Cummins Onan oil pressure sender, or Murphy EG series sender, this is the correct genuine Murphy product. WHY MURPHY ES2P-100 / KEY BENEFITS GENUINE MURPHY BY ENOVATION CONTROLS — The ES2P-100 is a genuine Murphy product, manufactured by Enovation Controls (formerly FW Murphy Manufacturing), the originator of the Swichgage instrument line. Genuine Murphy senders are precision-calibrated at the factory to match the resistance curve expected by Murphy EG Series gauges and CAN I/O modules. Aftermarket knockoffs may have incorrect resistance values, poor calibration, or inconsistent output, leading to inaccurate pressure readings and false alarms. 2-WIRE UNGROUNDED (INSULATED RETURN) — The ES2P-100 is the 2-wire version with an insulated (ungrounded) return wire. This means the sender does NOT rely on the engine block or equipment frame as the electrical return path. The 2-wire ungrounded design is required for isolated-ground electrical systems — most commonly found on generators, gensets, and marine applications where the electrical system is intentionally isolated from the chassis/frame. If your system uses a chassis-grounded return, the 1-wire Murphy ESP-100 (Part Number 05701857) may be appropriate instead. 240-TO-33 OHM RESISTANCE OUTPUT — The ES2P-100 uses the standard Murphy resistance curve: 240 ohms at 0 PSI (empty/no pressure) decreasing to 33 ohms at 100 PSI (full scale). This resistance range is specific to Murphy EG Series instruments. The sender will NOT work correctly with gauges calibrated for other resistance curves (such as 10-180 ohms or 0-90 ohms). 100 PSI MAXIMUM RATING — Rated for 0-100 PSI (0-689 kPa / 0-6.89 bar). The ES2P-100 is the most common pressure range for engine oil pressure monitoring on diesel and natural gas engines in the 10-500 HP range. For higher pressure applications, Murphy offers the ES2PM-200 (200 PSI), ES2PM-300 (300 PSI), and ES2PMK-400 (400 PSI) senders. 1/8-27 NPT THREAD — Standard 1/8-inch NPT thread connection for direct installation into oil galleries, pressure ports, and manifold fittings on most industrial engines and equipment. Use appropriate thread sealant (PTFE tape or pipe dope) on installation. MANUFACTURER RECOMMENDS OFF-EQUIPMENT MOUNTING — Murphy recommends mounting the ES2P-100 off-equipment (remote-mounted via a hose or tube from the pressure source) to reduce vibration and heat exposure, extending sender life and maintaining calibration accuracy. An off-equipment mounting kit is available separately from Murphy. CIRCUIT PROTECTION REQUIRED — Murphy requires proper circuit protection with fuses or circuit breakers when wiring the ES2P-100. Always install appropriate overcurrent protection per Murphy's wiring instructions. ES2P-100 (2-WIRE) VS ESP-100 (1-WIRE) — WHICH DO I NEED? Murphy offers both 1-wire and 2-wire versions of the 100 PSI pressure sender: ESP-100 (Part Number 05701857) — 1-WIRE (GROUNDED): - Single signal wire; uses engine block/chassis as return path - For systems where the electrical ground is connected to the engine block or equipment frame - Simpler wiring (1 wire + chassis ground) - Common on: Standalone industrial engines, compressors, pump sets with chassis-grounded electrical systems ES2P-100 (Part Number 05701858) — 2-WIRE (UNGROUNDED) << THIS LISTING: - Two wires: signal + insulated return - Does NOT use chassis/engine block as return path - Required for isolated-ground electrical systems - Common on: Generators, gensets, marine engines, and any application where the electrical system is isolated from ground If you are unsure, check the wiring diagram for your Murphy gauge or instrument. If it shows two wires going to the pressure sender, you need the ES2P-100 (2-wire). If it shows one wire going to the sender with a ground symbol at the sender, you need the ESP-100 (1-wire). RESISTANCE TABLE (ES2P-100 / ESP-100) 0 PSI = 240 ohms (falling pressure) 25 PSI = 153 ohms (falling pressure) — Primary Calibration Point 50 PSI = ~100 ohms (falling pressure) 75 PSI = 67 ohms (falling pressure) — Secondary Calibration Point 100 PSI = 33 ohms (rising pressure) SPECIFICATIONS Part Number: Murphy ES2P-100 Murphy Part Number: 05701858 / 05-70-1858 Product Type: 2-Wire Ungrounded Resistive Pressure Sender Product Series: ESP / ES2P Series Pressure Range: 0–100 PSI (0–689 kPa) [0–6.89 bar] Resistance Range: 240 Ohms (0 PSI) to 33 Ohms (100 PSI) Thread Size: 1/8-27 NPT Wiring: 2-Wire Ungrounded (Insulated Return) Compatible Instruments: Murphy EG Series Swichgage Instruments, CAN I/O Modules Mounting: Off-Equipment Mounting Recommended Circuit Protection: Fuses or Circuit Breakers Required Made by: Murphy by Enovation Controls (Tulsa, Oklahoma, USA) Quantity in This Listing: 1 (One) PART NUMBER FAMILY / CROSS REFERENCE MURPHY ESP/ES2P SERIES PRESSURE SENDERS — ALL MODELS: 80 PSI RANGE: ESP-80 (05701860) — 1-Wire Grounded, 0–80 PSI ES2P-80 (05701867) — 2-Wire Ungrounded, 0–80 PSI 100 PSI RANGE: ESP-100 (05701857) — 1-Wire Grounded, 0–100 PSI ES2P-100 (05701858) — 2-Wire Ungrounded, 0–100 PSI << THIS LISTING ESDP-100 (05701859) — Dual Gage, 2-Wire Ungrounded, 0–100 PSI ES2P-150 (05707678) — 2-Wire Ungrounded, 0–150 PSI (Special Order) 200 PSI RANGE: ESPM-200 (05701753) — 1-Wire Grounded, 0–200 PSI ES2PM-200 (05701748) — 2-Wire Ungrounded, 0–200 PSI 300 PSI RANGE: ESPM-300 (05701751) — 1-Wire Grounded, 0–300 PSI ES2PM-300 (05701750) — 2-Wire Ungrounded, 0–300 PSI 400 PSI RANGE: ESPMK-400 (05702566) — 1-Wire Grounded, 0–400 PSI ES2PMK-400 (05702565) — 2-Wire Ungrounded, 0–400 PSI OEM / ALTERNATE PART NUMBERS: Onan 0193-0430-01 / 0193043001 — Cummins Onan Generator Cross Reference NOTE ON ES2P-60: Murphy also offers an ES2P-60 (Part Number 00003040) — 2-Wire Ungrounded, 0–60 PSI, for lower-pressure applications. APPLICATIONS AND COMPATIBILITY The Murphy ES2P-100 is designed for pressure monitoring on any system or equipment that uses Murphy EG Series Swichgage instruments or compatible CAN I/O modules with 240-to-33 ohm resistive input. GENERATORS AND GENSETS: - Fits Cummins Onan generators — confirmed OEM application - Onan generator models: MDKAA, MDKAB, MDKAD, MDKAE, MDKAF, MDKAL, MDKAU, MDKAV, MDKAW, MDKAZ, MDKBD, MDKBE, MDKBF, MDKBG, MDKBH, MDKBK, MDKBL, MDKBM, MDKBN, MDKBP, MDKBR, MDKBS, MDKBV, MDKBT, MDKBU (Isolated Ground Models) - Onan OEM part number: 0193-0430-01 - Standby generators, prime power generators, portable gensets INDUSTRIAL ENGINES: - Diesel engines with Murphy instrumentation - Natural gas engines with Murphy instrumentation - Compressor drive engines - Pump set engines - Irrigation engines OIL AND GAS: - Wellhead compressors - Pipeline compressors - Production equipment with Murphy panels - Gas plant engines MARINE: - Marine diesel engines with isolated-ground electrical systems - Marine generators CONSTRUCTION AND MINING: - Construction equipment with Murphy gauges - Mining support equipment IMPORTANT FITMENT NOTES: - The ES2P-100 is a RESISTIVE SENDER — it outputs a variable resistance (240-33 ohms) proportional to pressure. It is NOT a voltage-output transducer or 4-20mA transmitter. - This sender is designed specifically for Murphy EG Series Swichgage instruments and compatible CAN I/O modules. It will not read correctly on gauges calibrated for different resistance curves. - If your system uses a grounded (chassis-return) wiring scheme, use the ESP-100 (05701857) 1-wire version instead. - The ES2PMK-400 and ESPMK-400 (400 PSI models) are NOT recommended for use with digital I/O modules — Murphy recommends the PXT-K pressure transmitter for those applications. ABOUT MURPHY BY ENOVATION CONTROLS Murphy by Enovation Controls represents over 80 years of reliable innovation for critical engine monitoring and control. Founded in 1939 by Frank W. "Pat" Murphy, FW Murphy Manufacturing transformed the world of engine instrumentation with the release of the innovative Safety Switch. Today, the Murphy brand operates under Enovation Controls, a stand-alone subsidiary of Helios Technologies (NYSE: HLIO), headquartered in Tulsa, Oklahoma, USA. With an internationally diverse team of over 300 employees, Enovation Controls serves customers worldwide with global sales, manufacturing, and application engineering operations. The Murphy brand has become synonymous with rugged, reliable engine protection and monitoring products for industrial engines, generators, compressors, marine, oil and gas, and construction applications.