Products & Services


GLT-500 Ground Monitors


Now MSHA Approved!

The GLT-500 ground monitors are patented, state-of-the-art, fail-safe, continuity Ground Monitors (GMs) for use in low, medium and high voltage applications (system voltages up to 5kV). These GMs feature Ground Lock TechnologyTM, a patented technology to monitor ground currents with greatly improved accuracy and reliability.

The GLT-500, GLT-500-1, GLT-AT500, AND GLT-AT500-1 are approved by MSHA for LV/MV applications, and unlike most ground monitors commonly in use today, meet all current MSHA testing standards.The GLT monitors are the only new ground monitors approved by MSHA in over two decades.

The GLT-500 family includes full-chassis versions (GLT-500/GLT-AT500) and open frame models (GLT-500-1/GLT-AT500-1). The full chassis models are mechanically and electrically compatible (pin-to-pin) with popular GMs that have been in use for several decades, so an upgrade is usually as simple as removing the old unit, and installing the new monitor in its place. The open frame models are electronically identical to the full chassis versions, except they do not include latching breaker trip indicators. 

The GLT-500 and GLT-500-1 require diode-type Ground Wire Devices (GWDs) such as the 1100-6020, while the GLT-AT500 and GLT-AT-500-1 use coil-type GWDs, such as the 1100-6010. When using a coil-type GWD, a separate current transformer (PN 2000-0308) is also required.
To download the spec sheet click here.
To download the users manual click here.  




 1020-0051 PWD

 1100-6010 GWD

 100-6020 GWD w/ CT

A typical installation includes one of the GLT family of ground monitors, a high voltage Pilot Wire Device (PWD), a special Current Transformer (CT) and a suitable Ground Wire Device (GWD). 


 2000-0308 CT

The PWD (PN 1020-0051) for the GLT family has been specially designed for use with the GLT monitors, and is included with each GM.

Two Intermountain Electronics GWDs are available for use with the GLT monitors in all applications not requiring MSHA approved GWDs: 1100-6020 is a diode-type GWD to be used with the GLT-500/GLT-500-1 (this GWD also integrates the necessary CT), while the 1100-6010 is a coil-type GWD used with the GLT-AT500/GLT-AT500-1. When using the 1100-6010, a separate CT (PN 2000-0308) must also be used. For MSHA applications, please contact IE for GWD recommendations. 


Intermountain Electronics understands the costs that occur when a power system is off line. This is why the GLT-500 Drawout Enclosure has been designed to dramatically reduce the downtime associated with replacing a GLT-500 or GLT-AT500 ground monitor. 

For more information, click here.


Expansion Modules

The GLT ground monitors and the GMS-504DZ include an accessory port compatible with Intermountain Electronics expansion modules. These expansion modules (available separately) can be easily installed to dramatically increase interconnectivity and signal monitoring capabilities. 

For more information, see the Expansion Modules Page


Ground Monitor Ordering Information

Model Part # Description 
GLT-500 1100-1000 GLT-500 Ground Monitor with 1020-0051 PWD (Requires GWD)  
GLT-500 Combo 1100-1007 GLT-500 Ground Monitor with 1020-0051 PWD, Plus 1100-6020 GWD  
GLT-500 MSHA Combo 1100-1008 GLT-500 Ground Monitor with 1020-0051 PWD, Plus MSHA Approved GWD  
GLT-500-1 1100-1002 GLT-500-1 Open Frame Ground Monitor with 1020-0051 PWD (Requires GWD)  
GLT-AT500 1100-1020 GLT-AT500 Ground Monitor with 1020-0051 PWD (Requires GWD/CT)  
GLT-AT500 Combo 1100-1027 GLT-AT500 GM with 1020-0051 PWD, 1100-6010 GWD, and 2000-0308 CT   
GLT-AT500 MSHA Combo 1100-1028 GLT-AT500 GM with 1020-0051 PWD, 2000-0308 CT, MSHA Approved GWD   
GLT-AT500-1 1100-1022  GLT-AT500-1 GM with 1020-0051 PWD (Requires GWD and 2000-0308 CT)  

Compatible Ground Monitor Accessories

Part # Description
1100-6010 Ground Wire Device (GWD) for GLT-AT500/GLT-AT500-1, Coil type, requires 2000-0308 CT  
2000-0308 Current Transformer (CT) for GLT-AT500/GLT-AT500-1  
1100-6020 Ground Wire Device (GWD) for GLT-500/GLT-500-1. Anti-parallel diodes w/ CT  
1100-7100 Expansion module with D-Sub and barrier strip  
1100-7110 Expansion module with dual barrier strips  
1020-0051 High-voltage Pilot Wire Device (included with all GLT ground monitors) for use up to 5kV  
A2315-001 Low-voltage/Medium-voltage PWD designed for use at <1kV  
1020-0078 Quick-Connect Fanning Strip (8-pins) for simple installation and removal of GLT-500 / GLT-500-1  
1020-0078 GLT-500 Drawout Assembly.  Other related drawout accessories are available--refer to spec sheet for more info