You've highlighted a very interesting and potentially counterintuitive point that Mike Holt makes. Let's break down why he might say that objectionable current is a greater sparking risk than high fault current in the context of loose connections in hazardous locations.Here's the core idea: It's not JUST the amount of current, it's the DURATION and STABILITY of the arc that matters.Fault Current Scenario (High Amperage, Short Duration)



High Magnitude

When a fault occurs (e.g., a line conductor touches a metal enclosure), a massive current surge happens VERY quickly. Think 100s to 1000s of amps, depending on the available fault current and system impedance.

Rapid Clearing

Protective devices like circuit breakers or fuses are designed to rapidly interrupt this fault current. This interruption happens in milliseconds.

Potential for Initial Arc, But Fast Extinction

Yes, the initial connection might produce a significant arc due to the high current trying to jump the gap of the loose locknut. However, the

extremely short duration of the fault current is a key factor. The arc is quenched almost immediately by the rapid tripping of the overcurrent protection device. The heat generated in those milliseconds might not be enough to consistently ignite flammable vapors or dusts. Solid Welding

As Mike Holt mentioned, the sheer magnitude of the fault current can sometimes "weld" or fuse the loose connection together, creating a more solid (albeit temporary) path back to the source, reducing further arcing. This is a less likely scenario, but a possibility.

Objectionable Current Scenario (Lower Amperage, Longer Duration)



Lower Magnitude

Objectionable current is typically within the normal circuit current range, often a few amps to tens of amps.

Persistent Flow

Objectionable current is continuous. It flows whenever the circuit is energized because there's an alternate path for neutral current returning through the equipment grounding conductor.

Sustained Arcing

A loose connection in the path of objectionable current creates a

persistent, but weak arc. Because the current is relatively low, it doesn't weld the connection together. Instead, it produces a flickering, unstable arc that lasts for a significant time (hours, days, weeks...) as long as the circuit is energized. Ignition Risk

This low-level, sustained arcing is potentially MUCH MORE DANGEROUS. The constant heat generated by the arc, even though it's small, has ample time to ignite flammable vapors or dusts that may accumulate around the loose connection.

Hidden Danger

Because objectionable current is lower in magnitude, it might not be immediately obvious or trip a breaker. It can persist for long periods of time, creating a constant ignition source.

Analogy

Think of it like this:

Fault Current

A firecracker. A brief, intense flash and bang.

Objectionable Current

A constantly sparking, smoldering cigarette butt.The firecracker might be louder, but the cigarette butt has a far higher probability of starting a slow-burning, destructive fire.

Why Hazardous Locations Are Different

In ordinary locations, a brief arc from a fault might cause annoyance or minor damage. But in hazardous locations, the presence of flammable materials amplifies the risk. The sustained arcing from objectionable current creates a constant ignition source, which is a significant hazard.

Key Takeaways

While fault current is certainly dangerous, the combination of

lower current and longer duration makes objectionable current a greater ignition hazard in hazardous locations. Bonding bushings and jumpers are crucial to ensure a low-impedance path for fault current and to minimize the flow of objectionable current through potentially loose connections. Proper grounding and bonding practices are essential to prevent both types of current from creating hazardous arcs and sparks.

Important Note: This explanation is based on my understanding of electrical principles and common safety practices. Always consult the NEC, relevant industry standards, and qualified professionals for specific applications and installations. Flag for review