HVAC Procedure and Performance Guide

TASK: Test equipment for ground

Training for this procedure can be found in these courses:

                         131 – Oil Heat l  and  161 – Boilers l


Presence or absence of continuity to ground in a specified circuit must be determined. Test device must be calibrated, connected and operated according to manufacturer’s instructions.  Applicable safety procedures must be followed.


      1. Review manufacturer’s specifications and wiring diagrams.
      2. Collect tools, equipment and materials.
      3. Put on safety and protective equipment and apparel.
      4. Identify equipment or circuit to be tested and locate test points using wiring diagrams or visual inspection.
      5. Disconnect electrical power to equipment.
      6. Remove access cover(s) and isolate circuit or equipment if applicable.
      7. Connect ground lead of megger to ground and connect other lead to equipment or circuit. (Note: When megging a winding or circuit component, connect megger as close to winding or component as possible.)
      8. Determine resistance to ground and record findings.(Note: Moisture or grease film at connection points may result in false readings.)
      9. Disconnect megger and reconnect circuit; replace access cover(s).
      10. Leave equipment in desired operating status. (Note: It may not be desirable to operate grounded equipment.)
      11. Remove safety and protective equipment and apparel.
      12. Gather tools, equipment and leftover materials and leave work site clean.