Electrical reference chart
Ground Fault Loop Chart
Use this worksheet after the calculator result to record loop impedance, prospective fault current, conductor path, equipment grounding path, connection resistance, and protective-device review.
Quick reference table
A ground fault loop chart is a calculator-led protection planning worksheet. It connects loop impedance and prospective fault current with the conductor path and protective-device follow-up before breaker or equipment review.
Ground fault loop worksheet
| Item | Record from calculator | Follow-up |
|---|---|---|
| Voltage and source | System voltage and transformer/source data | Confirm actual supply condition |
| Circuit path | Conductor size, material, and length | Check installed route and temperature basis |
| Grounding path | EGC size and path assumptions | Verify bonding and terminations |
| Loop impedance | Ohms or milliohms result | Compare with measured loop test if available |
| Protection | Prospective fault current | Check protective-device clearing and rating |
Ground-fault path review lanes
| Path item | Record on worksheet | Reason for separate review |
|---|---|---|
| Equipment grounding path | Conduit, EGC, bonding jumper, raceway notes | The fault path may not match the phase conductor path |
| Protective device | Breaker, fuse, GFPE, relay, setting | Clearing depends on device type and actual settings |
| Available fault current | Source and transformer basis | Prospective current changes with upstream source data |
| Field verification | Continuity, impedance, or test method note | A calculation does not prove installed bonding condition |
How to use this chart
Trace the fault path
Record every source, conductor, grounding, and connection assumption used in the loop result.
Compare protection data
Use the prospective fault current only with verified breaker, fuse, or relay information.
Flag field verification
Document whether measurement, continuity testing, or equipment-duty review is still needed.
Formula basis
Prospective fault current = system voltage / ground-fault loop impedance.
- System voltage is the line voltage used by the calculator for the fault path.
- Loop impedance includes source, conductor, equipment grounding path, and connection resistance assumptions.
- Prospective fault current is the calculated current available for the selected loop path.
- Protective-device review compares the result with breaker, fuse, or relay behavior using verified equipment data.
Worked examples
Branch-circuit loop record
Record source voltage, transformer impedance, conductor length, EGC size, connection resistance, calculated loop impedance, prospective fault current, and breaker follow-up.
Equipment bonding troubleshooting note
Document the panel, raceway path, bonding jumper, measured continuity concern, protective-device setting, and expected clearing review before changing equipment.
Related calculators
Ground Fault Loop Calculator
Calculate ground fault loop impedance (Zs) and prospective fault current. Verify protective device coordination against the adopted NEC edition, equipment documentation, and AHJ requirements.
Short Circuit Current Calculator
Estimate available fault current from transformer impedance, feeder impedance, or known source impedance.
Circuit Breaker Sizing Calculator
Calculate standard breaker sizes for general loads, continuous loads, and simplified motor branch-circuit reviews
Grounding Calculator
NEC Article 250 grounding and bonding conductor screen for main bonding jumpers, equipment grounding conductors, and grounding electrode conductors.
Related charts
Short Circuit Current Chart
Plan short-circuit current checks from utility data, transformer kVA and impedance, voltage, conductor path, motor contribution, and equipment SCCR/AIC.
Breaker Size Chart
Plan breaker size from load category, continuous duty, conductor protection, interrupting rating, equipment listing, and calculator result notes.
Grounding Resistance Chart
Use a grounding resistance chart to document soil assumptions, electrode geometry, measured ohms, target basis, spacing notes, and field-test follow-up.
Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.