The same NFPA 77 threshold, applied to two very different real-world bonding-clip readings ā one a clean pass, one a clear failure needing immediate attention.
| Threshold | 1,000,000 Ī© (1 MĪ©) ā commonly-cited NFPA 77 static-dissipation guidance |
| Case A ā measured bonding resistance | 25,000 Ī© (a bonding clip on a truck with some surface corrosion) |
| Case B ā measured bonding resistance | 2,500,000 Ī© (a clip with a failed or missing connection) |
The calculator distinguishes a tight metallic bond (very low resistance) from one that merely clears the static-dissipation threshold.
| Check | Requirement | Actual | Status |
|---|---|---|---|
| Case A bonding resistance | ā¤ 1,000,000 Ī© | 25,000 Ī© | ā PASS |
| Case B bonding resistance | ā¤ 1,000,000 Ī© | 2,500,000 Ī© | ā FAIL |
Key insight: There's a meaningful difference between 'passes the threshold' and 'is a good connection.' A reading like Case A's 25,000 Ī© clears the 1 MĪ© static-dissipation limit with huge margin, but is still two to three orders of magnitude higher than a properly tight all-metal bond ā which is exactly the kind of early warning sign (corrosion, a loose clamp, paint on the contact surface) worth acting on before it degrades into an actual failure like Case B.
Every input in this example is editable in the live calculator ā free, no signup.
Open Static Bonding & Grounding Check calculator āStatic charge dissipation doesn't need a low-impedance path the way a fault-current or lightning path does ā it only needs to bleed off a slow accumulation of static charge fast enough to prevent a dangerous voltage buildup, and NFPA 77's commonly-cited 1 MĪ© guidance reflects that far more modest requirement, which is why a bonding path can be orders of magnitude worse than a proper equipment ground and still work for its intended static-dissipation purpose.
No ā static dissipation, equipment (fault-current) grounding, and lightning protection all have different, unrelated impedance requirements. A bonding clip that passes this static-dissipation check at 25,000 Ī© would be completely inadequate as an equipment safety ground, which typically needs an impedance low enough to ensure protective devices operate quickly during a fault.