ST-47 Groundhog Static Ground Proving Control Unit

Vehicle Static Ground Verification System

  • Self-proving technology based on Scully’s original patented design
  • Can operate in conjunction with your Scully Overfill Prevention System (ST-35® or ST-15) or as an independent ground verification unit
  • Immediately shuts down the loading operation if proper static grounding is not detected

  • Can be used with a variety of loading operations including tank trucks, rail tank cars, aircraft refuelers and tanks to ensure that transport vehicles are properly tied to ground before and during the loading operation
  • The ST-47 Static Grounding system continuously monitors the ground connection and if that connection is lost, the ST47 will non-permit
  • For stand-alone grounding without overfill prevention, choose the junction box with choice of Scully ground-proving plug or grounding clamp
  • For static ground verification in conjunction with your Scully Overfill Prevention system, wire the ST-47 through your Overfill Prevention Control Monitor and plug and cable for one quick overfill protection and static grounding/earthing connection
  • Direct earthing tie-in point at loading rack is available


08508ST-47-115 ELGroundhog Control Monitor with Lamps (115 VAC)
08220ST-47-115 ELKGroundhog Control Monitor with Lamps and Key Bypass Switch (115 VAC)
08675ST-47-240 ELGroundhog Control Monitor with Lamps (240 VAC)
08502ST-47-240 ELKGroundhog Control Monitor with Key Bypass Switch (240 VAC)



08249SC-47Heavy-Duty Junction Box, with 20′ straight cable and ground proving plug for connection to vehicle-mounted ground proving ball (independent system)
08567SC-47CCHeavy-Duty Junction Box, with 32′ coiled cable and ground proving plug for connection to vehicle-mounted ground proving ball (independent system)
08653SC-47CC/DHeavy-Duty Junction Box, with 32’ coiled cable and ground proving plug with additional circuitry for deadman switch; aviation applications



08815NVST-47CC/CLMPSculcon Junction Box, with grounding clamp and 32’ coiled cable
09333ST-47/CLMPSculcon Junction Box, with grounding clamp and 20’ straight cable



08274Ground Ball, truck-mounted electronic ground proving ball for independent grounding system
08560Ground Bolt, truck-mounted electronic ground proving bolt for wiring to overfill prevention socket
08566Coiled Cable, replacement plug and 32′ coiled cable assembly for SC-47
08219Straight Cable Replacement Plug and 20′ Straight Cable Assembly for SC-47
08565Plug, replacement plug only for SC-47
09511Module 115, replacement module for 115 VAC models
27005Bulb, 135V, replacement indicator lamp bulb for 115 VAC older models
09384LED Bulb- Red LED Candelabra for 120V
09512Module 240- Replacement Module for 240 VAC Models
27006Bulb, 250V- Replacement Indicator Lamp Bulb for 240 VAC Models
09385LED Bulb- Green LED Candelabra for 120V
08863Deadman Control- Deadman Switch with Coiled Cable

For replacement parts for The Grounding Verification Clamp unit, please see Ground Verification Clamp and Cable Unit data sheet

Some applications such as rail lines and pipelines may also have stray currents present. In these situations, the rail or pipeline must be bonded to ground independently from the Scully ST-47 system.

Operation Temperature:-40˚ to +140˚ F (-40˚ to +60˚ C)
Enclosure:Explosion-Proof Weather-Proof Housing, suffix “E”
Indicators:Red−not grounded/non-permit. Green−grounded/permit.
Response Time:0.5 seconds maximum.
Electrical Connections:Internal terminal strips, identified for easy installation.
Bypass Switch:Key lockable off-on bypass switch for ELK model only.
Output Control:One normally open user contact rated 250, 5A resistive load.
Power Requirements:ST-47–115 Models: 105–125 VAC, 50/60 Hz. 0.250 Amperes maximum.
ST-47–240 Models: 208–240 VAC, 50/60 Hz.0.125 Amperes maximum.
Shipping Weights:ST-47 ELK; 26 lbs (12 kgs)
ST-47 EL; 26 lbs (12 kgs)
SC-47; 9 lbs (4 kgs)
Approvals:Explosion-proof with intrinsically safe ground connection outputs. Rated for Class I, Division 1, Groups C & D Hazardous (Classified) Locations, by FM Global (FM) to Canadian and United States standards.

Scully Signal