GCM

GCM

Gradient Control Mat

Personnel working near pipelines can be subject to electrical hazards such as lightning, AC fault current/voltage, and steady-state AC induction. "Ground mats" have typically been used at above ground pipeline structures where these hazards exist, but many designs do not provide adequate protection against lightning conditions.

Dairyland offers engineered Gradient Control Mats (GCM) to address lightning and AC fault current conditions effectively. Safety risks from step and touch potentials are now limited with the Dairyland grid-type mat, in a much lower cost design. Dairyland also recommends decoupling gradient control mats to improve CP on the pipeline, and offers the Solid-State Decoupler (SSD) line for use in conjunction with the Gradient Control Mat.

Features and Characteristics

  • Low cost design
  • Galvanized steel grid, using 3" x 3" squares
  • Low inductance design limits step and touch potentials due to lightning
  • Decoupling the mat offers long life and improved CP on the pipeline
  • Data available on design life and supplemental anodes

 
      

Literature:
GCM - One Page Data Sheet
GCM - Technical Literature
GCM - Installation Instructions

Support Documents:
GCM Cathodic Protection Design Guidelines
NACE Paper 05617: Gradient Control Mat Safety Considerations in Pipeline Applications

Application Assistance:
Gradient Control Mat Decoupling

The PCRH has been tested by a Nationally Recognized Testing Laboratory (NRTL) for compliance to independent standards in its operation, ratings, and construction. This includes compliance to standards for:

Safety Grounding

UL (United States) and C-UL (Canada) listing for:

  • Providing an "effective ground-fault current path" as defined in 2002 NFPA 70 (US National Electrical Code - NEC), Article 250.2, and required in 250.4 (A)(5)
  • Similarly, it meets the same per Canadian Standards Association CSA C22.2 No. 0.4-M1982 (reaffirmed 1999), using Canadian Electrical Code Part I, section 10-500, 10-806 as a guide.
  • Providing over-voltage protection in accordance with the applicable requirements of ANSI C62.11

Listing assures compliance to the above standards by DEI devices in providing electrical over-voltage protection and safety grounding.

Blocking Cathodic Protection Current

  • Providing DC isolation of objectionable DC ground currents from cathodic protection systems as defined in NFPA 70, Article 250.6(E)

HAZARDOUS LOCATION USE

The PCRH has been listed for use in Class I, Divisions 1 & 2, Groups B, C, D hazardous locations by UL and C-UL, according to:

  • U.S. National Electrical Code section 500-505
  • UL 1203: "Explosion-proof and Dust-Ignition Proof Electrical Equipment for Hazardous (Classified) Locations"
  • CSA C22.2 No.30-M1986: "Explosion-Proof Enclosures for Use in Class I Hazardous Locations"

Comparison of Dairyland model PCRH to other solid-state devices

Following on the success of the model PCR, the Dairyland model PCRH offered fully certified products for Class I, Division 1 hazardous locations. There are no equivalents to the model PCRH, however it is common for others to place a protection product inside of a commercially available explosion-proof box and erroneously consider the entire package to be considered "explosion-proof." Altering a certified enclosure nullifies the listing or certification unless the entire package is again tested and recertified. Dairyland has taken the route of full testing and certification for the model PCRH, as it is used in explosive atmospheres. The device was successfully tested and certified.

The PCRH has extensive certification. In fact, no other products of this type on the market have any known certification to any standards whatsoever. Consider the following PCRH certifications:

  • UL listed as an "effective grounding path" per the US National Electrical Code (NEC)
  • UL listed for blocking cathodic protection current per the US NEC
  • UL listed as meeting the lightning surge current standards
  • UL listed for Class I, Division 1 & 2 hazardous locations
  • UL listed NEMA 4 environmental rating
  • C-UL listed as an "effective grounding path" per the Canadian Electrical Code
  • C-UL listed for Class I, Division 1 & 2 hazardous locations

Other features include:

  • Unique, patented construction that assures maintenance-free operation
  • Assured fail-safe design, independently tested
  • Proprietary manufacturing methods that assure corrosion resistance, high AC fault capability, and low leakage current

For more information on PCRH certification, see the full data sheet.

Gradient Control Mat
Quantity Weight Packaged Dimensions
50 825 4'x8'x18"
100 1650 4'x8'x35"

Note: For other Gradient Control Mat models or quantities, contact Dairyland for more information.